{"gene":"RAD51","run_date":"2026-04-28T19:45:45","timeline":{"discoveries":[{"year":1994,"finding":"Human RAD51 protein binds single- and double-stranded DNA, exhibits DNA-dependent ATPase activity, underwinds duplex DNA in an ATP-dependent reaction, and forms helical nucleoprotein filaments on nicked duplex DNA resembling RecA/yeast Rad51 filaments, establishing it as a functional RecA homolog.","method":"Protein purification, ATPase assay, topological unwinding assay, electron microscopy","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 — reconstitution with purified protein, multiple orthogonal biochemical methods","pmids":["7988572"],"is_preprint":false},{"year":1996,"finding":"Human RAD51 promotes ATP-dependent homologous pairing and strand exchange reactions in vitro; joint molecule formation requires ATP hydrolysis and DNA homology and is stimulated by RPA; hRad51 initiates strand exchange but requires additional proteins for extensive heteroduplex formation.","method":"In vitro strand exchange assay with purified proteins, ATP hydrolysis measurement","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in vitro strand exchange with purified human RAD51","pmids":["8929543"],"is_preprint":false},{"year":1997,"finding":"Human RAD51 (HsRad51) promotes homologous pairing and strand exchange at rates less than 1/10 those of RecA; in the presence of ATP-γ-S, HsRad51 forms stable presynaptic complexes and promotes renaturation but not strand exchange or homologous pairing with duplex DNA, suggesting homologous pairing and strand exchange are more closely linked to ATP hydrolysis in HsRad51 than in RecA.","method":"In vitro recombination assays, ATP hydrolysis assays, stoichiometry of DNA binding","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — rigorous in vitro biochemistry with purified human RAD51, multiple assay types","pmids":["9012806"],"is_preprint":false},{"year":1997,"finding":"BRCA1 colocalizes with RAD51 in discrete nuclear foci during S phase and the two proteins co-immunoprecipitate; BRCA1 residues 758–1064 form RAD51-containing complexes in vitro; both proteins associate with developing synaptonemal complexes in meiotic cells, indicating a functional interaction in DNA repair and recombination.","method":"Co-immunoprecipitation, immunofluorescence co-localization, in vitro binding, meiotic chromosome spreads","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 — reciprocal co-IP plus in vitro binding, replicated in multiple cellular contexts","pmids":["9008167"],"is_preprint":false},{"year":1997,"finding":"RAD51 interacts specifically with the eight BRC motifs encoded in exon 11 of BRCA2; RAD51 residues 98–339 are sufficient to interact with the 59-residue minimal conserved BRC motif, mapping the molecular interface between RAD51 and BRCA2.","method":"Yeast two-hybrid, biochemical deletion analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — yeast two-hybrid plus biochemical mapping, foundational interaction study","pmids":["9405383"],"is_preprint":false},{"year":1997,"finding":"BRCA2 protein physically interacts with RAD51 during mouse embryogenesis; Brca2-deficient embryos show developmental arrest and radiation hypersensitivity mediated by RAD51, indicating BRCA2 is an essential cofactor in RAD51-dependent repair of double-strand breaks.","method":"Co-immunoprecipitation, mouse knockout, radiation sensitivity assay","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis in mouse model plus co-IP, replicated across labs","pmids":["9126738"],"is_preprint":false},{"year":1998,"finding":"ATP and Mg2+ binding induces a conformational change in Rad51 detected by circular dichroism spectroscopy, producing a more structured state; this active conformation is required for DNA binding; ATP-γ-S also stabilizes activity but AMP-PNP does not, and DNA significantly increases Rad51's affinity for ATP.","method":"Equilibrium dialysis (nucleotide binding), circular dichroism spectroscopy, thermal inactivation assay","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 — multiple biophysical methods with purified protein establishing mechanistic conformational change","pmids":["9718317"],"is_preprint":false},{"year":1998,"finding":"BRCA2 gene product forms in vivo complexes with both p53 and RAD51 as a nuclear phosphoprotein; exogenous BRCA2 inhibits p53 transcriptional activity and RAD51 co-expression enhances this effect, placing BRCA2 at the intersection of cell cycle control and DNA repair via RAD51.","method":"Co-immunoprecipitation in vivo, nuclear fractionation, transcriptional reporter assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo co-IP plus functional reporter, single lab study","pmids":["9811893"],"is_preprint":false},{"year":1998,"finding":"RAD51 accumulates at sites of UV-induced DNA damage in human S-phase cells and is preferentially associated with postreplicative (rather than actively replicating) chromatin, demonstrating that RAD51 redistribution to damaged chromatin occurs from pre-existing S-phase foci.","method":"UV microirradiation, BrdU/IdU dual-label fractionation, immunofluorescence microscopy","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — direct localization with functional context, multiple imaging approaches","pmids":["10908572"],"is_preprint":false},{"year":2000,"finding":"Human RAD51 paralogs XRCC2, XRCC3, RAD51B, RAD51C, and RAD51D form simultaneous protein interactions; yeast three-hybrid experiments show several pairs interact concurrently (e.g., RAD51B enhances RAD51C binding to XRCC3 and RAD51D); baculovirus co-expression confirms multi-subunit complex formation, suggesting these paralogs assemble into one or more complexes.","method":"Yeast two-hybrid, yeast three-hybrid, His-tag pull-down from baculovirus co-expression","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal interaction methods, simultaneous complex formation demonstrated","pmids":["10749867"],"is_preprint":false},{"year":2000,"finding":"Gamma-H2AX phosphorylation after DNA double-strand breaks is necessary for recruitment of RAD51 (and RAD50, BRCA1) to nuclear foci; wortmannin (PI-3 kinase inhibitor) prevents gamma-H2AX formation and abolishes RAD51 focus formation, placing PI-3 kinase signaling and H2AX upstream of RAD51 recruitment.","method":"Immunofluorescence, wortmannin inhibition, laser-induced DSBs in human cells","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 2 — epistasis via chemical inhibition plus co-localization, foundational study with wide replication","pmids":["10959836"],"is_preprint":false},{"year":2000,"finding":"Mammalian Rad51 and Rad52 co-localize in distinct nuclear foci upon DNA damage in murine cells expressing GFP-Rad52; cells expressing GFP-Rad52 show increased survival and increased Rad51 foci, indicating Rad52 is limiting for Rad51-mediated repair and the two proteins function together in the DNA damage response.","method":"GFP-Rad52 live-cell imaging, immunofluorescence, survival assay","journal":"EMBO reports","confidence":"Medium","confidence_rationale":"Tier 2 — direct co-localization with functional consequence, single-lab study","pmids":["11256631"],"is_preprint":false},{"year":2001,"finding":"BRCA2 plays a dual role in regulating RAD51: BRC3 and BRC4 repeats block RAD51 nucleoprotein filament formation; cancer-associated BRC3 mutations abolish this effect; additionally, BRCA2 controls nuclear import of RAD51, with a cancer-associated BRCA2 truncation causing defective nuclear RAD51 localization.","method":"In vitro filament formation assays, nuclear transport assays, cancer mutation analysis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution plus mutagenesis plus cellular localization with cancer-relevant mutations","pmids":["11239456"],"is_preprint":false},{"year":2001,"finding":"HsRad51 is required for triplex-induced intermolecular recombination between plasmid targets in human cell-free extracts; depletion of HsRad51 with specific antibodies diminishes triplex-induced recombination and supplementation with purified HsRad51 restores it.","method":"Cell-free extract reconstitution, antibody depletion, purified protein supplementation","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1 — cell-free reconstitution with depletion/add-back, but single lab","pmids":["11278954"],"is_preprint":false},{"year":2002,"finding":"Crystal structure of a BRC repeat–RAD51 RecA-homology domain complex reveals that the BRC repeat mimics the RAD51 oligomerization interface, enabling BRCA2 to control RAD51 nucleoprotein filament assembly; cancer-associated BRC mutations disrupt predicted RAD51 contacts.","method":"X-ray crystallography, structure-guided mutational analysis","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 — high-resolution crystal structure plus cancer mutation interpretation","pmids":["12442171"],"is_preprint":false},{"year":2002,"finding":"Human Rad54 promotes transient strand separation in duplex DNA via ATP hydrolysis-driven DNA supercoiling; its ATPase, supercoiling, and strand-opening activities are greatly stimulated by interaction with hRad51; hRad51 and hRad54 functionally cooperate in the homologous DNA pairing reaction.","method":"In vitro ATPase assay, DNA supercoiling assay, strand opening assay, homologous pairing assay with purified proteins","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — multiple in vitro reconstitution assays with purified human proteins","pmids":["12205100"],"is_preprint":false},{"year":2002,"finding":"FANCD2 co-localizes with RAD51 in S-phase-specific nuclear foci upon DNA damage; monoubiquitination of FANCD2 is required for this co-localization and for normal cell-cycle progression after mitomycin C exposure, placing FANCD2 in the same S-phase repair pathway as RAD51.","method":"Immunofluorescence co-localization, cell-cycle fractionation, FA mutant cell analysis","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 — co-localization with genetic evidence from FA mutant cells, single lab","pmids":["12239151"],"is_preprint":false},{"year":2002,"finding":"RPA stabilizes RAD51-generated DNA pairing intermediates in a critical postsynaptic role during strand exchange; RPA binds the displaced strand to stabilize pairing, whereas its presynaptic role in facilitating filament formation is minimal under conditions that minimize ssDNA secondary structure.","method":"In vitro strand exchange assay with purified Rad51 and RPA, deproteinization controls","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — mechanistic dissection of pre- vs. post-synaptic RPA roles using purified proteins","pmids":["12169690"],"is_preprint":false},{"year":2003,"finding":"Yeast DNA helicase Srs2 binds Rad51, possesses robust ssDNA-stimulated ATPase activity, and at catalytic quantities causes severe inhibition of Rad51-mediated recombination by dislodging Rad51 from ssDNA, thereby dismantling the presynaptic filament.","method":"In vitro ATPase assay, Rad51 filament disruption assay, pulldown","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in vitro with purified proteins, mechanistic demonstration of filament dismantling","pmids":["12748644"],"is_preprint":false},{"year":2003,"finding":"Rad52 forms complexes with Rad51, RPA, and Rad59; Rad51-Rad52-Rad59 and RPA-Rad52-Rad59 complexes depend on Rad52 for formation; the N-terminal Rad52 self-interaction domain is required for Rad59 interaction, implicating distinct Rad52 complexes in conservative and single-strand annealing recombination pathways.","method":"Co-immunoprecipitation, two-hybrid, in vitro binding","journal":"DNA repair","confidence":"Medium","confidence_rationale":"Tier 2 — multiple interaction methods, mechanistic pathway placement","pmids":["13679150"],"is_preprint":false},{"year":2005,"finding":"RAD51 focus formation in response to ionizing radiation is dependent on BRCA2 and the five RAD51 paralogs (RAD51B, RAD51C, RAD51D, XRCC2, XRCC3), whereas spontaneous S-phase RAD51 foci form without requiring these factors, revealing two distinct modes of RAD51 nuclear focus assembly.","method":"Immunofluorescence in paralog/BRCA2-deficient cell lines, DNA damage-induced focus assay","journal":"Philosophical transactions of the Royal Society of London. Series B, Biological sciences","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis using defined mutant cell lines, replicated across multiple paralog mutants","pmids":["15065660"],"is_preprint":false},{"year":2005,"finding":"BRCA2 BRC repeats (BRC3/BRC4) at low concentrations bind and form stable complexes with RAD51-DNA nucleoprotein filaments; BRC3 contacts the N-terminal domain of RAD51 while BRC4 contacts the nucleotide-binding core, demonstrating nonequivalent and distinct binding modes within the filament.","method":"Electron microscopy of RAD51-DNA filaments with BRC peptides, cryo-EM image reconstruction","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — structural analysis by EM with domain mapping of two distinct binding sites","pmids":["15937124"],"is_preprint":false},{"year":2005,"finding":"CDK-mediated phosphorylation of BRCA2 at serine 3291 during late cell cycle blocks the C-terminal BRCA2–RAD51 interaction; this phosphorylation is low in S phase when recombination is active and increases toward mitosis; DNA damage decreases S3291 phosphorylation to re-enable RAD51 binding, providing a molecular switch for recombination regulation.","method":"Phospho-specific antibody, cell-cycle fractionation, in vitro kinase assay, co-immunoprecipitation","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 — identified PTM writer (CDK), mapped site, functional consequence of phosphorylation on RAD51 interaction","pmids":["15800615"],"is_preprint":false},{"year":2005,"finding":"Chk1 interacts with RAD51 and phosphorylates RAD51 on Thr309 in a Chk1-dependent manner; loss of Chk1 by siRNA or chemical inhibition abolishes RAD51 focus formation after hydroxyurea; a phosphorylation-deficient RAD51(T309A) mutant causes hydroxyurea hypersensitivity, establishing Chk1 as a regulator of RAD51-mediated homologous recombination repair.","method":"Co-immunoprecipitation, phospho-specific antibody, siRNA, chemical inhibitors, RAD51-T309A mutant phenotyping","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 1–2 — PTM identified (writer: Chk1, site: T309), mutagenesis of phosphosite, epistatic loss-of-function","pmids":["15665856"],"is_preprint":false},{"year":2005,"finding":"BRCA2 and BRCA1 form a stable biochemical complex that co-localizes with RAD51 at replication sites after hydroxyurea or UV damage in S-phase cells and on synaptonemal complexes in meiosis, placing both tumor suppressors together in the same RAD51-mediated repair pathway.","method":"Co-immunoprecipitation, immunofluorescence co-localization, meiotic chromosome spreads","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 — in vivo complex formation plus co-localization in multiple cell contexts, replicated","pmids":["9774970"],"is_preprint":false},{"year":2005,"finding":"MDC1 directly interacts with RAD51 through its forkhead-associated (FHA) domain; MDC1 knockdown impairs RAD51 focus formation after ionizing radiation, reduces nuclear and chromatin-bound RAD51, and increases RAD51 protein degradation, indicating MDC1 retains RAD51 in chromatin to facilitate homologous recombination.","method":"Co-immunoprecipitation, siRNA knockdown, chromatin fractionation, immunofluorescence","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 2 — direct interaction mapped to domain, multiple functional consequences of depletion","pmids":["16186822"],"is_preprint":false},{"year":2006,"finding":"The L1 loop residue Tyr232 of human RAD51 is critical for DNA binding; alanine or conservative tryptophan substitution significantly decreases DNA-binding ability without affecting protein folding or salt-induced ATPase; fluorescence spectroscopy confirms L1 and L2 loops are positioned near the DNA-binding site.","method":"Site-directed mutagenesis, gel retardation assay, DNA-dependent ATPase assay, fluorescence spectroscopy","journal":"The FEBS journal","confidence":"High","confidence_rationale":"Tier 1 — active-site mutagenesis with multiple functional readouts","pmids":["16780572"],"is_preprint":false},{"year":2007,"finding":"Both Rad51 ATPase activity and Rad54 ATPase activity are required for efficient Rad51 turnover from dsDNA (product dissociation); the Rad54 ATPase is stimulated by partial Rad51 filaments on dsDNA; the Rad51-K191R Walker-box mutant has increased filament stability and defective dsDNA binding, demonstrating that Rad51's own ATPase activity is needed for normal presynaptic and postsynaptic filament dynamics.","method":"In vitro ATPase kinetics, electron microscopy of filaments, Walker-box mutant analysis","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in vitro with mutant and WT proteins, mechanistic dissection of two ATPases","pmids":["17567608"],"is_preprint":false},{"year":2008,"finding":"Human Rad51 specifically inhibits Rad52-mediated annealing of complementary ssDNA in an ATP-dependent manner via a direct Rad51–Rad52 interaction; the Rad51 nucleoprotein filament is more inhibitory than free Rad51; Rad59 partially restores Rad52-dependent annealing in the presence of Rad51, suggesting Rad51 channels repair toward strand invasion over annealing.","method":"In vitro ssDNA annealing assay, protein interaction analysis, ATP dependency experiments","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in vitro biochemistry with purified yeast proteins, multiple conditions tested","pmids":["18337252"],"is_preprint":false},{"year":2008,"finding":"Human Rad51 stimulates branch migration activity of human Rad54 through specific protein–protein interactions; the active (ATP-bound) Rad51 filament conformation is more stimulatory than the inactive form; this stimulation is evolutionarily conserved (also seen with yeast proteins), indicating Rad51 allosterically regulates Rad54's branch migration function.","method":"In vitro branch migration assay, protein–protein interaction analysis, yeast and human protein comparison","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in vitro, mechanistic demonstration of allosteric stimulation, confirmed in two species","pmids":["18617519"],"is_preprint":false},{"year":2009,"finding":"Human PSF directly interacts with RAD51 via its N-terminal region and modulates RAD51 activity in a concentration-dependent manner: PSF enhances RAD51-mediated homologous pairing and strand exchange at low RAD51 concentrations but inhibits these activities at optimal RAD51 concentrations, suggesting dual regulatory roles.","method":"Co-immunoprecipitation/pulldown, in vitro homologous pairing assay, strand exchange assay, deletion analysis","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 1–2 — in vitro reconstitution with mapped interaction domain, single lab","pmids":["19447914"],"is_preprint":false},{"year":2010,"finding":"Purified full-length BRCA2 binds RAD51 and stimulates RAD51-mediated recombination by: (1) targeting RAD51 to ssDNA over dsDNA, (2) enabling RAD51 to displace RPA from ssDNA, and (3) stabilizing RAD51-ssDNA filaments by blocking ATP hydrolysis. BRCA2 does not directly catalyze ssDNA annealing.","method":"Full-length BRCA2 purification, in vitro strand exchange assay, filament stability assay, RPA displacement assay","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 — first purification of full-length BRCA2 with reconstituted mechanistic assays, multiple orthogonal methods","pmids":["20729832"],"is_preprint":false},{"year":2010,"finding":"RAD51 mediates two distinct replication responses: stalled replication forks (HU short-term) are restarted in a RAD51-dependent, XRCC3-dependent manner without triggering HR; collapsed forks (prolonged HU) undergo RAD51-dependent HR repair without apparent restart, showing that restart and repair represent distinct RAD51 pathways.","method":"DNA fiber assay, siRNA knockdown, XRCC3 mutant cells, RAD51 focus formation","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis with multiple mutant lines, fiber assay distinguishing two pathways","pmids":["20188668"],"is_preprint":false},{"year":2011,"finding":"In budding yeast, Rad51 is phosphorylated on Ser192 primarily by the checkpoint kinase Mec1 in response to DNA damage; Rad51-S192A or S192E mutations confer DNA damage hypersensitivity and HR defects; Ser192 is required for Rad51 ATPase activity and DNA binding in vitro but not for multimer formation.","method":"Mass spectrometry phosphosite identification, in vitro kinase assay, HR assay, ATPase assay, DNA binding assay","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 1 — PTM writer (Mec1) identified, site mapped, in vitro biochemical phenotype characterized","pmids":["21738226"],"is_preprint":false},{"year":2014,"finding":"HOP2-MND1 heterodimer acts as a 'molecular trigger' of RAD51 by inducing conformational changes that enhance RAD51's interaction with nucleotide cofactors, modify DNA-binding specificity, enable strand exchange without divalent metal ions, offset K133A ATP-binding mutation defects, restrict dsDNA binding during filament formation, and promote dsDNA binding during homology search.","method":"In vitro strand exchange assay, nucleotide binding assay, ssDNA/dsDNA binding assay with HOP2-MND1 and mutant RAD51","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 — multiple in vitro reconstitution assays with mechanistic dissection","pmids":["24943459"],"is_preprint":false},{"year":2015,"finding":"RAD51-mediated replication fork reversal is a global response to diverse genotoxic treatments in human cells; electron microscopy of replication fork architecture shows uncoupling and reversal are frequent; RAD51 is present at replication forks independently of breakage; fork reversal is RAD51-dependent and antagonized by PARP/RECQ1-regulated restart.","method":"Electron microscopy of replication fork architecture, siRNA depletion, EM quantification of fork reversal","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1–2 — direct EM visualization of fork structures plus RAD51 depletion, global genotoxic treatment panel","pmids":["25733714"],"is_preprint":false},{"year":2015,"finding":"The C. elegans Rad51 paralog complex RFS-1/RIP-1 binds and remodels pre-synaptic RAD-51-ssDNA filaments into a stabilized, 'open,' flexible conformation in which ssDNA is more accessible and RAD-51 dissociation rate is reduced; Walker-box mutations in RFS-1 abolish filament remodeling and fail to stimulate strand exchange, demonstrating remodeling is essential for paralog function.","method":"Single-molecule FRET, electron microscopy, in vitro strand exchange assay, Walker-box mutagenesis","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 — multiple orthogonal structural and biochemical methods, mutagenesis validation","pmids":["26186187"],"is_preprint":false},{"year":2016,"finding":"TOPBP1 promotes PLK1 kinase-mediated phosphorylation of RAD51 at serine 14, a modification required for RAD51 recruitment to chromatin and focus formation; TOPBP1 BRCT domains 7/8 are essential for RAD51 foci; TOPBP1 depletion abrogates RAD51 chromatin loading without affecting upstream resection or RPA loading.","method":"siRNA screen, phospho-specific antibody, in vitro kinase assay, chromatin fractionation, BRCT mutants","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — PTM writer (PLK1) identified, site (S14) mapped, upstream regulator (TOPBP1) identified, multiple loss-of-function approaches","pmids":["26811421"],"is_preprint":false},{"year":2016,"finding":"The MMS22L-TONSL heterodimer localizes to replication forks, associates with RPA-coated ssDNA, and directly interacts with RAD51 via MMS22L; recombinant MMS22L-TONSL limits RAD51 assembly on dsDNA, stimulating RAD51-ssDNA filament formation and strand exchange; MMS22L-RAD51 interaction is required for proper RAD51 focus assembly and HR-mediated fork restart.","method":"Co-immunoprecipitation, in vitro strand exchange assay with purified proteins, mutant cell analysis, iPOND replication fork proteomics","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1–2 — in vitro reconstitution plus in vivo epistasis, multiple methods","pmids":["27797818"],"is_preprint":false},{"year":2017,"finding":"Human RAD52 binds tightly to RPA-ssDNA complexes and inhibits RPA turnover; during presynaptic complex assembly, RAD51 displaces most RAD52-RPA from ssDNA; once RAD51 is assembled, it restricts new RAD52 binding events, revealing reciprocal regulation between RAD51 and RAD52 at the presynaptic filament.","method":"Single-molecule imaging, ssDNA curtains, TIRF microscopy","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — single-molecule reconstitution of individual protein dynamics on ssDNA","pmids":["28551686"],"is_preprint":false},{"year":2017,"finding":"Srs2 is a processive translocase that strips Rad51 monomers from ssDNA at ~50 monomers/second; Srs2 is recruited to RPA clusters embedded within Rad51 filaments; multi-Srs2 arrays form via iterative loading; Srs2 disrupts heteroduplex DNA joints through two alternative pathways, establishing the mechanism of Srs2-mediated anti-recombination.","method":"Single-molecule fluorescence imaging (ssDNA curtains), TIRF microscopy","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 1 — single-molecule visualization of Srs2 acting on Rad51 filaments in real time","pmids":["29241544"],"is_preprint":false},{"year":2018,"finding":"RADX antagonizes RAD51 at stalled replication forks by competing with RAD51 for ssDNA binding; silencing RADX restores fork protection in BRCA1/2-, FANCA-, FANCD2-, or BOD1L-deficient cells; RADX overexpression causes fork degradation dependent on MRE11 and DNA2 and fork reversal, establishing that the RAD51/RADX balance determines stalled fork fate.","method":"DNA fiber assay, siRNA, RADX overexpression, iPOND, fork protection assays","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 — epistasis across multiple HR-deficient backgrounds, direct ssDNA competition assay","pmids":["30021152"],"is_preprint":false},{"year":2018,"finding":"In budding yeast, Rad52–Rad51 protein interaction is dispensable for Rad51 filament formation and gene conversion but is essential for protecting Rad51 filaments against dissociation by Srs2 DNA translocase, revealing a filament-protection function of Rad52–Rad51 association independent of mediator activity.","method":"Rad52 interaction-deficient mutants, in vitro Srs2-disruption assay, in vivo gene conversion assay, electron microscopy","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1–2 — separation-of-function mutants with in vitro and in vivo validation","pmids":["29985128"],"is_preprint":false},{"year":2018,"finding":"Rad51 and Dmc1 have an intrinsic ability to self-segregate in mixed filaments on ssDNA, even without accessory proteins; Dmc1 stabilizes adjacent Rad51 filament segments, suggesting the two meiotic recombinases form spatially distinct but cross-stabilizing filament domains.","method":"Single-molecule imaging (ssDNA curtains), co-visualization of labeled Rad51 and Dmc1","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — single-molecule visualization directly demonstrating self-segregation","pmids":["29382724"],"is_preprint":false},{"year":2020,"finding":"RADX condenses RPA-coated ssDNA filaments via higher-order assemblies that can capture ssDNA in trans; RADX blocks RPA displacement by RAD51 and prevents RAD51 loading on ssDNA, establishing RADX as an ssDNA condensation protein that inhibits RAD51 filament formation.","method":"Single-molecule imaging of RADX on RPA-ssDNA, TIRF microscopy, RAD51 loading assay","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 — direct single-molecule visualization of RADX mechanism at physiological protein ratios","pmids":["32621611"],"is_preprint":false},{"year":2021,"finding":"RADX directly and selectively interacts with ATP-bound RAD51, stimulates RAD51 ATP hydrolysis, and destabilizes RAD51 nucleofilaments, inhibiting strand exchange and D-loop formation; RADX ssDNA-binding capability plus its RAD51 interaction are both required for maintaining replication fork elongation and stability; BRCA2 can overcome RADX-mediated RAD51 inhibition.","method":"In vitro strand exchange assay, ATPase assay, RAD51 filament stability assay, DNA fiber assay, RADX–RAD51 interaction mapping","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in vitro mechanism with purified proteins plus cellular validation","pmids":["33453169"],"is_preprint":false},{"year":2021,"finding":"HELQ helicase activity is strongly stimulated by RAD51 (which forms a complex with HELQ) during DNA unwinding; conversely, RPA inhibits HELQ unwinding but stimulates a previously unappreciated HELQ DNA strand annealing activity; HELQ can capture RPA-bound DNA strands and displace RPA to facilitate annealing.","method":"In vitro helicase and annealing assays, single-molecule imaging, biochemical co-complex analysis","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in vitro with single-molecule imaging, mechanistic dissection","pmids":["34937945"],"is_preprint":false},{"year":2021,"finding":"The HsRAD51B-HsRAD51C heterodimer forms stable complexes on ssDNA and partially stabilizes the HsRAD51 nucleoprotein filament against BLM-mediated disruption; it stimulates HsRAD51-mediated D-loop formation in the presence of RPA but does not facilitate HsRAD51 nucleation on RPA-coated ssDNA, placing RAD51B-C function downstream of BRCA2 in filament stabilization during the presynaptic phase.","method":"In vitro filament stability assay, D-loop assay, ssDNA binding assay with purified proteins","journal":"DNA repair","confidence":"Medium","confidence_rationale":"Tier 1 — reconstituted in vitro with purified proteins, but single lab, moderate complexity","pmids":["23810717"],"is_preprint":false},{"year":2021,"finding":"Conditional knockout of RAD51 in mouse germ cells (Vasa-Cre) causes spermatogonial loss and Sertoli cell-only syndrome; inducible adult knockout causes meiotic DSB accumulation, reduced pachytene spermatocytes, and fewer crossovers, establishing an essential role for RAD51 in spermatogonial maintenance and meiotic DSB repair.","method":"Conditional mouse knockout (Vasa-Cre and UBC-CreERT2), γH2AX staining, crossover quantification","journal":"Cell death discovery","confidence":"High","confidence_rationale":"Tier 2 — direct loss-of-function in vivo with specific molecular phenotypes","pmids":["35292640"],"is_preprint":false},{"year":2022,"finding":"TOPORS acts as a SUMO E3 ligase for RAD51, SUMOylating RAD51 at lysines 57 and 70 in response to DNA damage; SUMOylation is facilitated by ATM-induced phosphorylation of TOPORS at Thr515; SUMOylation-deficient RAD51 (K57R/K70R) reduces chromatin loading, RAD51 focus formation, and association with BRCA2, impairing HR repair.","method":"SUMO modification assay, phospho-specific antibody, SUMOylation-deficient mutants, co-immunoprecipitation, HR reporter assay","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1–2 — PTM writer (TOPORS), sites (K57, K70) mapped, upstream signal (ATM-TOPORS) identified, functional consequence characterized","pmids":["35061896"],"is_preprint":false},{"year":2022,"finding":"RAD51 Cys319 is a redox-sensitive residue regulated by PRDX1; oxidation of Cys319 (sulfenylation) impairs irradiation-induced RAD51 focus formation and HR; PRDX1 maintains Cys319 in a reduced state; molecular dynamics simulations show that oxidized Cys319 causes dissociation of DNA from the RAD51 filament.","method":"Phospho/sulfenylation probes, PRDX1-deficient cells, RAD51-C319 mutagenesis, molecular dynamics simulation, PARP inhibitor sensitivity","journal":"Redox biology","confidence":"High","confidence_rationale":"Tier 1–2 — site-specific oxidation mapped, mutagenesis, MD simulation, multiple functional readouts","pmids":["36058112"],"is_preprint":false},{"year":2023,"finding":"Cryo-EM structure of the BRCA2 TR2 motif bound to the human RAD51 nucleoprotein filament reveals TR2 binds across the protomer interface, acting as a brace for adjacent RAD51 molecules; TR2 targets an acidic-patch motif on RAD51 that also serves as a recruitment hub for recombination mediators in fission yeast.","method":"Cryo-electron microscopy, structure-guided mutagenesis","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 — cryo-EM structure plus mutagenesis validation","pmids":["37919288"],"is_preprint":false},{"year":2023,"finding":"Cryo-EM structures of human RAD51-DNA and DMC1-DNA complexes reveal that the Loop2 region (containing ssDNA and complementary strand binding residues) differs between RAD51 and DMC1; RAD51 residues V273 and D274 (vs. P274 and G275 in DMC1) are key determinants of mismatch intolerance during strand exchange, explaining RAD51's high fidelity compared to DMC1's mismatch tolerance.","method":"Cryo-EM structure determination, molecular dynamics simulation, single-molecule FRET, mutagenesis","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 — cryo-EM structures plus mutagenesis and single-molecule validation","pmids":["34871438"],"is_preprint":false},{"year":2023,"finding":"RAD51 uses its strand exchange activity to bypass the replicative helicase (CMG) that remains bound at stalled replication forks; when CMG is unloaded, RAD51 is no longer required for fork reversal; RAD51 creates a parental DNA duplex behind the helicase that DNA translocases then use as substrate for branch migration to generate a reversed fork.","method":"Auxin-inducible degron to acutely deplete CMG, DNA fiber assay, EM of replication forks, RAD51 strand exchange mutants","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1–2 — mechanistic genetic epistasis with CMG depletion, strand exchange–specific mutants, EM visualization","pmids":["37104614"],"is_preprint":false},{"year":2023,"finding":"BRCA2 chaperones a short preassembled RAD51 filament onto RPA-coated ssDNA; a dimer of RAD51 is the minimal unit for spontaneous nucleation but growth self-terminates below diffraction limit; BRCA2 accelerates RAD51 nucleation to rates approaching binding to naked ssDNA, eliminating the kinetic barrier imposed by RPA.","method":"Single-molecule microfluidics with full-length BRCA2, direct visualization of RAD51 filament assembly on RPA-ssDNA","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — single-molecule reconstitution with full-length BRCA2, quantitative kinetic measurements","pmids":["36976771"],"is_preprint":false},{"year":2023,"finding":"Human centromeres harbor enrichment of DNA breaks that occur during both proliferation and quiescence; centromere DNA breaks in quiescent cells are resolved by the RAD51 recombinase, which safeguards functional centromere specification.","method":"Single-cell imaging of DNA breaks at repetitive centromere regions, RAD51 depletion, centromere function assay","journal":"Molecular cell","confidence":"Medium","confidence_rationale":"Tier 2 — direct imaging plus RAD51 depletion phenotype, novel cellular context","pmids":["36702125"],"is_preprint":false},{"year":2023,"finding":"Functionally tagged Rad51 in budding yeast forms exceedingly long nucleoprotein filaments spanning the entire nucleus after DSB induction; filaments adopt dynamic compaction-extension cycles modulated by Rad54 (promoting compaction) and Srs2 (promoting extension/disassembly); biophysical modeling shows this dynamics constitutes a robust homology search strategy.","method":"Live-cell single-molecule imaging with functional tagged Rad51, biophysical modeling, DSB induction","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 2 — first direct in vivo tracking of functional tagged Rad51 filaments, quantitative biophysical model","pmids":["37605042"],"is_preprint":false},{"year":2024,"finding":"RAD51 nucleofilaments specifically recognize and protect abasic sites in ssDNA (which increase RAD51's DNA association rate); in the absence of BRCA2 or RAD51, abasic ssDNA gaps accumulate making replicating DNA sensitive to APE1; RAD51 assembled on abasic DNA prevents cleavage by the MRE11-RAD50 complex, suppressing replication fork breakage.","method":"Cryo-EM of RAD51 on abasic DNA, Xenopus egg extract assays, human cell experiments, APE1/MRE11 cleavage assays","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 — cryo-EM structure revealing abasic site recognition plus reconstituted fork protection assays in two model systems","pmids":["39178838"],"is_preprint":false}],"current_model":"RAD51 is a RecA-family ATPase that assembles onto ssDNA to form a nucleoprotein filament—stabilized by BRCA2 (which nucleates the filament and blocks ATP hydrolysis) and regulated by TOPBP1/PLK1-mediated S14 phosphorylation, Chk1-mediated T309 phosphorylation, TOPORS-mediated K57/K70 SUMOylation, CDK-mediated BRCA2-S3291 phosphorylation, and redox control of C319—that catalyzes homology search and ATP-dependent strand exchange with duplex DNA (inhibited by Srs2/RADX, stimulated by Rad54/HOP2-MND1/PSF), and additionally functions in replication fork reversal by using its strand exchange activity to bypass the CMG helicase, in fork protection by shielding nascent DNA and abasic sites from MRE11/RAD50 nucleolytic degradation, and in meiotic DSB repair and spermatogenesis."},"narrative":{"teleology":[{"year":1994,"claim":"Identifying RAD51 as a functional human RecA homolog resolved whether eukaryotes possess a dedicated strand-exchange recombinase: purified human RAD51 bound DNA, hydrolyzed ATP, unwound duplexes, and formed helical nucleoprotein filaments.","evidence":"Protein purification, ATPase assay, topological unwinding, electron microscopy of filaments","pmids":["7988572"],"confidence":"High","gaps":["No strand exchange demonstrated yet","Cofactor requirements unknown","No in vivo functional proof"]},{"year":1996,"claim":"Demonstrating that human RAD51 catalyzes ATP-dependent homologous pairing and strand exchange in vitro established the core enzymatic activity of the protein, while revealing that its intrinsic rate is much lower than RecA and requires accessory factors for extensive heteroduplex formation.","evidence":"In vitro strand exchange assay with purified hRAD51 and RPA","pmids":["8929543","9012806"],"confidence":"High","gaps":["Identity of required accessory factors unknown","Relationship between ATP hydrolysis and strand exchange kinetics unclear"]},{"year":1997,"claim":"Discovery of direct BRCA2–RAD51 and BRCA1–RAD51 interactions placed the hereditary breast cancer tumor suppressors in the homologous recombination pathway, with BRCA2's BRC repeats providing the molecular interface to RAD51.","evidence":"Co-immunoprecipitation, yeast two-hybrid mapping of BRC motifs to RAD51 residues 98–339, BRCA2-null mouse embryo phenotyping","pmids":["9405383","9126738","9008167"],"confidence":"High","gaps":["How BRCA2 mechanistically promotes RAD51 activity unknown","Full-length BRCA2 not yet purified","BRCA1's direct role vs. indirect scaffolding unclear"]},{"year":1998,"claim":"ATP/Mg²⁺-induced conformational switching of RAD51 and its accumulation at UV-damaged chromatin during S phase established that RAD51 adopts a catalytically competent conformation upon nucleotide binding and functions in the context of DNA replication.","evidence":"Circular dichroism spectroscopy, equilibrium dialysis, UV microirradiation with BrdU fractionation","pmids":["9718317","10908572"],"confidence":"High","gaps":["Structural basis of conformational change unknown","Whether RAD51 foci represent active filaments unclear"]},{"year":2000,"claim":"Placing γ-H2AX upstream of RAD51 focus formation and identifying RAD51 paralog complexes (RAD51B/C/D, XRCC2/3) defined the signaling hierarchy: PI-3 kinase–dependent H2AX phosphorylation is required for RAD51 recruitment, and paralog sub-complexes act as mediators.","evidence":"Wortmannin inhibition of γ-H2AX abolishes RAD51 foci; yeast two/three-hybrid and baculovirus co-expression of paralog complexes","pmids":["10959836","10749867"],"confidence":"High","gaps":["Direct mechanism by which paralogs load RAD51 unknown","Paralog complex stoichiometry undefined"]},{"year":2002,"claim":"Crystal structure of the BRC repeat–RAD51 complex revealed that BRC mimics the RAD51 protomer–protomer interface, explaining how BRCA2 controls filament assembly; concurrently, RPA's postsynaptic role in stabilizing strand exchange products and Rad54's ATP-dependent cooperation with RAD51 were mechanistically dissected.","evidence":"X-ray crystallography of BRC–RAD51; in vitro strand exchange with RPA deproteinization controls; Rad54 supercoiling/branch migration assays","pmids":["12442171","12169690","12205100"],"confidence":"High","gaps":["Full-length BRCA2 not structurally resolved","How individual BRC repeats differ in function unclear","Rad54's in vivo contribution to branch migration not tested"]},{"year":2003,"claim":"Discovery that Srs2 helicase dismantles RAD51 presynaptic filaments established the first anti-recombination mechanism targeting RAD51 directly, providing a framework for understanding how inappropriate recombination is prevented.","evidence":"In vitro reconstitution with purified Srs2 and Rad51; filament disruption assay","pmids":["12748644"],"confidence":"High","gaps":["Human Srs2 functional ortholog not identified","Whether Rad52 can counteract Srs2 unknown"]},{"year":2005,"claim":"Multiple regulatory inputs were identified: CDK phosphorylation of BRCA2-S3291 gates RAD51 binding across the cell cycle, Chk1 phosphorylation of RAD51-T309 is required for damage-induced focus formation, and MDC1 retains RAD51 on chromatin—collectively establishing that RAD51 is regulated by checkpoint kinases, CDK, and chromatin adaptor proteins.","evidence":"Phospho-specific antibodies, cell-cycle fractionation, in vitro kinase assays, siRNA, RAD51-T309A mutagenesis, MDC1 FHA-domain mapping","pmids":["15800615","15665856","16186822"],"confidence":"High","gaps":["Interplay between T309 and S14 phosphorylation not explored","Whether CDK-BRCA2-S3291 is the sole cell-cycle switch unclear"]},{"year":2010,"claim":"Purification of full-length BRCA2 finally demonstrated its direct biochemical mechanism: BRCA2 nucleates RAD51 filaments by targeting RAD51 to ssDNA, displacing RPA, and blocking RAD51's ATP hydrolysis to stabilize the active filament; concurrently, DNA fiber analysis separated RAD51's fork restart function from its HR repair function.","evidence":"Full-length BRCA2 purification with in vitro strand exchange, filament stability, and RPA displacement assays; DNA fiber assay in XRCC3-mutant and siRAD51 cells","pmids":["20729832","20188668"],"confidence":"High","gaps":["Whether BRCA2 forms a stoichiometric or catalytic complex with RAD51 unclear","Structural basis of BRCA2 blocking ATP hydrolysis unknown"]},{"year":2015,"claim":"RAD51-mediated replication fork reversal was established as a global cellular response to genotoxic stress, and RAD51 paralog complexes were shown to remodel presynaptic filaments into an 'open' conformation that facilitates strand exchange, defining the structural output of paralog action.","evidence":"EM of replication fork architecture in human cells after RAD51 depletion; single-molecule FRET and EM of RFS-1/RIP-1 filament remodeling in C. elegans","pmids":["25733714","26186187"],"confidence":"High","gaps":["Whether human RAD51B-C or RAD51C-XRCC3 remodel filaments analogously unknown","Specific RAD51 domains required for fork reversal not mapped"]},{"year":2018,"claim":"RADX was identified as a ssDNA-binding antagonist of RAD51 at stalled forks, and Rad52 was shown to protect Rad51 filaments from Srs2 disruption—together establishing that the balance between filament stabilizers and destabilizers determines fork protection versus degradation.","evidence":"DNA fiber assays across BRCA1/2- and FA-deficient backgrounds with RADX silencing; separation-of-function Rad52 mutants with Srs2 disruption assay in vitro and in vivo","pmids":["30021152","29985128"],"confidence":"High","gaps":["Whether RADX acts identically at DSB-associated ssDNA unclear","Human RAD52's filament-protective role not directly tested"]},{"year":2021,"claim":"Mechanistic dissection of RADX revealed it directly binds ATP-bound RAD51 and stimulates its ATPase to destabilize filaments; MMS22L-TONSL was shown to limit RAD51 dsDNA binding to promote productive ssDNA filament formation; and conditional RAD51 knockout in mice demonstrated essential roles in spermatogonial maintenance and meiotic crossover formation.","evidence":"In vitro ATPase/strand exchange with RADX and RAD51; iPOND and reconstitution with MMS22L-TONSL; Vasa-Cre and UBC-CreERT2 conditional knockouts in mouse germ cells","pmids":["33453169","27797818","35292640"],"confidence":"High","gaps":["RADX structural basis of RAD51 interaction unknown","MMS22L-TONSL mechanism of ssDNA selectivity not structurally explained"]},{"year":2022,"claim":"Two new regulatory layers were discovered: TOPORS SUMOylates RAD51 at K57/K70 downstream of ATM to promote chromatin loading and BRCA2 interaction, and PRDX1 maintains RAD51-C319 in a reduced state required for DNA binding, establishing redox and SUMO control of filament competence.","evidence":"SUMO modification assays with TOPORS, SUMOylation-deficient RAD51-K57R/K70R mutants, HR reporter; sulfenylation probes, PRDX1-deficient cells, RAD51-C319 mutagenesis, molecular dynamics","pmids":["35061896","36058112"],"confidence":"High","gaps":["Interplay between SUMOylation and phosphorylation of RAD51 not characterized","Whether C319 oxidation occurs under physiological oxidative stress in vivo not established"]},{"year":2023,"claim":"Cryo-EM structures resolved how BRCA2's TR2 motif braces adjacent RAD51 protomers across the filament interface and how RAD51 Loop2 residues V273/D274 enforce mismatch intolerance during strand exchange; in vivo imaging revealed nucleus-spanning RAD51 filaments that undergo Rad54/Srs2-modulated compaction-extension cycles to conduct homology search; and RAD51 strand exchange activity was shown to bypass the CMG helicase at stalled forks to initiate fork reversal.","evidence":"Cryo-EM of BRCA2-TR2–RAD51 and RAD51/DMC1–DNA complexes; live-cell single-molecule imaging of tagged Rad51 filaments; auxin-inducible CMG depletion with EM and fiber assays","pmids":["37919288","34871438","37605042","37104614"],"confidence":"High","gaps":["Full cryo-EM structure of BRCA2-loaded RAD51 filament not yet available","How filament compaction-extension is coordinated with chromatin architecture unknown","Structural basis of CMG bypass not resolved"]},{"year":2024,"claim":"RAD51 was found to specifically recognize and protect abasic sites in ssDNA from MRE11-RAD50 nucleolytic cleavage, expanding its fork-protection function beyond simple ssDNA coating to lesion-specific shielding of damaged replication intermediates.","evidence":"Cryo-EM of RAD51 on abasic DNA, Xenopus egg extract fork protection assays, human cell experiments with APE1/MRE11 cleavage readouts","pmids":["39178838"],"confidence":"High","gaps":["Whether other DNA lesion types are similarly recognized by RAD51 unknown","In vivo frequency and genomic distribution of abasic-site protection events not determined"]},{"year":null,"claim":"A comprehensive structural model of full-length BRCA2 bound to a complete RAD51 nucleoprotein filament during active strand exchange remains unresolved, as does the precise mechanism by which RAD51 filament dynamics are spatially coordinated with chromatin topology and replication fork architecture in mammalian cells.","evidence":"","pmids":[],"confidence":"High","gaps":["No full-length BRCA2–RAD51 filament structure available","Structural basis of RAD51's CMG bypass mechanism unresolved","How multiple PTMs are integrated in space and time during a single repair event is unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[0,1,2,6,27]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[0,1,6,26]},{"term_id":"GO:0140097","term_label":"catalytic activity, acting on DNA","supporting_discovery_ids":[1,2,34,53]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[3,8,10,12,56]},{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[8,25,37,55]}],"pathway":[{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[1,5,14,20,31,32,49]},{"term_id":"R-HSA-69306","term_label":"DNA Replication","supporting_discovery_ids":[32,35,41,53,57]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[22,37]},{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[43,48]}],"complexes":["RAD51 nucleoprotein filament","BRCA1-BRCA2-RAD51 complex"],"partners":["BRCA2","BRCA1","RAD54L","RAD52","RADX","MMS22L","TOPORS","HELQ"],"other_free_text":[]},"mechanistic_narrative":"RAD51 is a RecA-family recombinase that assembles ATP-dependent helical nucleoprotein filaments on single-stranded DNA to catalyze homology search and strand exchange, forming the central enzymatic activity of homologous recombination repair of DNA double-strand breaks, replication fork reversal, and nascent DNA protection [PMID:7988572, PMID:8929543, PMID:25733714, PMID:37104614]. Filament nucleation on RPA-coated ssDNA is rate-limited and overcome by BRCA2, which chaperones preassembled RAD51 onto ssDNA, blocks RAD51 ATP hydrolysis to stabilize the active filament, and targets RAD51 to ssDNA over dsDNA [PMID:20729832, PMID:36976771, PMID:12442171]; filament dynamics are further tuned by stimulatory cofactors (Rad54, HOP2-MND1, RAD51 paralogs, MMS22L-TONSL) and antagonists (Srs2, RADX, BLM) that respectively stabilize or dismantle filaments [PMID:12205100, PMID:24943459, PMID:12748644, PMID:33453169, PMID:27797818]. Multiple post-translational modifications regulate RAD51 chromatin loading and activity, including Chk1-mediated T309 phosphorylation, TOPBP1/PLK1-mediated S14 phosphorylation, TOPORS-dependent SUMOylation at K57/K70, CDK-dependent phosphorylation of BRCA2-S3291 that gates the BRCA2–RAD51 interaction across the cell cycle, and PRDX1-maintained reduction of the redox-sensitive C319 residue [PMID:15665856, PMID:26811421, PMID:35061896, PMID:15800615, PMID:36058112]."},"prefetch_data":{"uniprot":{"accession":"Q06609","full_name":"DNA repair protein RAD51 homolog 1","aliases":["RAD51 homolog A"],"length_aa":339,"mass_kda":37.0,"function":"Plays an important role in homologous strand exchange, a key step in DNA repair through homologous recombination (HR) (PubMed:12205100, PubMed:18417535, PubMed:20231364, PubMed:20348101, PubMed:22325354, PubMed:23509288, PubMed:23754376, PubMed:26681308, PubMed:28575658, PubMed:32640219). Binds to single-stranded DNA in an ATP-dependent manner to form nucleoprotein filaments which are essential for the homology search and strand exchange (PubMed:12205100, PubMed:18417535, PubMed:15226506, PubMed:20231364, PubMed:20348101, PubMed:23509288, PubMed:23754376, PubMed:26681308, PubMed:28575658). Catalyzes the recognition of homology and strand exchange between homologous DNA partners to form a joint molecule between a processed DNA break and the repair template (PubMed:12205100, PubMed:18417535, PubMed:20231364, PubMed:20348101, PubMed:23509288, PubMed:23754376, PubMed:26681308, PubMed:28575658, PubMed:38459011). Recruited to resolve stalled replication forks during replication stress (PubMed:27797818, PubMed:31844045). Part of a PALB2-scaffolded HR complex containing BRCA2 and RAD51C and which is thought to play a role in DNA repair by HR (PubMed:12442171, PubMed:24141787). Plays a role in regulating mitochondrial DNA copy number under conditions of oxidative stress in the presence of RAD51C and XRCC3 (PubMed:20413593). Also involved in interstrand cross-link repair (PubMed:26253028)","subcellular_location":"Nucleus; Cytoplasm; Cytoplasm, perinuclear region; Mitochondrion matrix; Chromosome; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome","url":"https://www.uniprot.org/uniprotkb/Q06609/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/RAD51","classification":"Common Essential","n_dependent_lines":1171,"n_total_lines":1208,"dependency_fraction":0.9693708609271523},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/RAD51","total_profiled":1310},"omim":[{"mim_id":"621430","title":"FIGNL1-INTERACTING REGULATOR OF RECOMBINATION AND MITOSIS; FIRRM","url":"https://www.omim.org/entry/621430"},{"mim_id":"621422","title":"TELOMERASE RNA COMPONENT-INTERACTING RNase; TRIR","url":"https://www.omim.org/entry/621422"},{"mim_id":"621002","title":"PREMATURE OVARIAN FAILURE 25; POF25","url":"https://www.omim.org/entry/621002"},{"mim_id":"621001","title":"SPERMATOGENIC FAILURE 96; SPGF96","url":"https://www.omim.org/entry/621001"},{"mim_id":"620693","title":"ASTEROID HOMOLOG 1; ASTE1","url":"https://www.omim.org/entry/620693"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoli","reliability":"Supported"},{"location":"Mitochondria","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"lymphoid tissue","ntpm":14.6},{"tissue":"testis","ntpm":22.6}],"url":"https://www.proteinatlas.org/search/RAD51"},"hgnc":{"alias_symbol":["HsRad51","HsT16930","BRCC5","FANCR"],"prev_symbol":["RAD51A","RECA"]},"alphafold":{"accession":"Q06609","domains":[{"cath_id":"1.10.150.20","chopping":"25-80","consensus_level":"high","plddt":95.7711,"start":25,"end":80},{"cath_id":"3.40.50.300","chopping":"96-335","consensus_level":"high","plddt":95.1997,"start":96,"end":335}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q06609","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q06609-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q06609-F1-predicted_aligned_error_v6.png","plddt_mean":91.44},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RAD51","jax_strain_url":"https://www.jax.org/strain/search?query=RAD51"},"sequence":{"accession":"Q06609","fasta_url":"https://rest.uniprot.org/uniprotkb/Q06609.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q06609/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q06609"}},"corpus_meta":[{"pmid":"20729832","id":"PMC_20729832","title":"Purified 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RPA from ssDNA and stabilizing RAD51-ssDNA filaments by blocking ATP hydrolysis. BRCA2 does not anneal RPA-complexed ssDNA, indicating it does not function directly in ssDNA annealing repair processes.\",\n      \"method\": \"Protein purification, in vitro biochemical reconstitution, DNA binding assays, strand exchange assays\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted with purified full-length BRCA2 and RAD51, multiple orthogonal assays in single rigorous study\",\n      \"pmids\": [\"20729832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Yeast Srs2 helicase binds Rad51 and disrupts the Rad51 presynaptic filament by dislodging Rad51 from ssDNA, thereby attenuating homologous recombination. Catalytic amounts of Srs2 severely inhibit Rad51-mediated recombination reactions in vitro.\",\n      \"method\": \"Protein purification, in vitro ATPase assays, Rad51 filament disruption assays, recombination reaction inhibition assays\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro with purified proteins, mechanistically defined filament disruption activity\",\n      \"pmids\": [\"12748644\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Yeast Rad54 protein interacts physically with Rad51 and possesses dsDNA-dependent ATPase activity; addition of Rad54 to Rad51-containing reactions strongly stimulates the rate of homologous DNA pairing between ssDNA and dsDNA substrates.\",\n      \"method\": \"Protein purification, co-immunoprecipitation, ATPase assay, DNA pairing (strand exchange) assay\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro with purified proteins, ATPase and strand pairing assays\",\n      \"pmids\": [\"9590697\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Purified human RAD51 (HsRad51) promotes homologous pairing and strand exchange in vitro, but with rates less than 1/10 those of E. coli RecA. HsRad51 forms stable presynaptic complexes with ATP-γ-S but fails to catalyze strand exchange or homologous pairing of ssDNA with duplex DNA in the presence of this analog, unlike RecA, suggesting that homologous pairing and strand exchange by HsRad51 are more closely linked to ATP hydrolysis.\",\n      \"method\": \"Protein purification from E. coli, in vitro ATPase assay, homologous pairing assay, strand exchange assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — purified human RAD51, multiple in vitro biochemical assays with rigorous controls\",\n      \"pmids\": [\"9012806\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Human Rad54 promotes transient strand separation in duplex DNA via ATP hydrolysis-driven DNA supercoiling; its ATPase, DNA supercoiling, and strand-opening activities are greatly stimulated through direct interaction with hRad51. hRad51 and hRad54 cooperate in the homologous DNA pairing reaction forming recombination intermediates.\",\n      \"method\": \"In vitro biochemical assays: ATPase, DNA supercoiling, strand separation, and homologous pairing assays with purified human proteins\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro with purified human proteins, multiple orthogonal biochemical assays\",\n      \"pmids\": [\"12205100\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"BRCA2 gene product forms in vivo complexes with both RAD51 and p53 in human cells, and exogenous BRCA2 expression inhibits p53 transcriptional activity; RAD51 coexpression enhances BRCA2's inhibitory effect on p53 transcription.\",\n      \"method\": \"Co-immunoprecipitation from human cells, immunoprecipitation, transcriptional reporter assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal co-IP and functional transcriptional assay, single lab\",\n      \"pmids\": [\"9811893\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"BRCA2 BRC repeat peptides (BRC3 and BRC4) bind RAD51-DNA nucleoprotein filaments at low molar ratios, stabilizing them; at high concentrations they disrupt filaments. BRC3 contacts the N-terminal domain of RAD51 while BRC4 contacts the nucleotide-binding core of RAD51, demonstrating that the two BRC repeats are nonequivalent in their mode of interaction.\",\n      \"method\": \"Electron microscopy of RAD51-DNA filaments incubated with BRC peptides, structural analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — EM structural analysis with functional interpretation, identification of distinct binding sites\",\n      \"pmids\": [\"15937124\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The C. elegans Rad51 paralog complex RFS-1/RIP-1 binds and remodels pre-synaptic RAD-51-ssDNA filaments to a stabilized, open, and flexible conformation that increases ssDNA accessibility and reduces RAD-51 dissociation rate, thereby stimulating RAD-51 strand exchange activity. Walker box mutations in RFS-1 abolish filament remodeling and fail to stimulate strand exchange, demonstrating remodeling is essential for function.\",\n      \"method\": \"In vitro biochemical reconstitution, single-molecule imaging, electron microscopy, ATPase mutagenesis, strand exchange assays\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution with purified proteins, structure (EM), mutagenesis, and functional assays in single study\",\n      \"pmids\": [\"26186187\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"TOPBP1 physically binds PLK1 and promotes PLK1 kinase-mediated phosphorylation of RAD51 at serine 14, a modification required for RAD51 recruitment to chromatin. TOPBP1 BRCT domains 7/8 are essential for RAD51 foci formation without affecting upstream HR steps (DNA end resection, RPA loading).\",\n      \"method\": \"siRNA screen, co-immunoprecipitation, kinase assay, immunofluorescence, chromatin fractionation\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods: co-IP, kinase assay, domain mapping, chromatin fractionation, functional rescue\",\n      \"pmids\": [\"26811421\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"RADX modulates stalled replication fork protection by antagonizing RAD51; RADX effectively competes with RAD51 for binding to ssDNA, reducing RAD51 filament formation. Silencing RADX restores fork protection in cells deficient for BRCA1, BRCA2, FANCA, FANCD2, or BOD1L. The amount of RAD51 on stalled forks determines fork fate: more RAD51 is required for fork protection than fork reversal.\",\n      \"method\": \"siRNA knockdown, DNA fiber assay, ssDNA competition binding assay, epistasis analysis with multiple HR mutants\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — epistasis across multiple mutant backgrounds, in vitro binding competition, DNA fiber assay, mechanistically defined\",\n      \"pmids\": [\"30021152\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"RADX directly and selectively interacts with ATP-bound RAD51, stimulates RAD51 ATPase activity, destabilizes RAD51 nucleofilaments, and inhibits RAD51 strand exchange and D-loop formation. The RADX interaction with RAD51 (in addition to ssDNA binding) is required to maintain replication fork elongation rates and stability. BRCA2 can overcome RADX-dependent RAD51 inhibition.\",\n      \"method\": \"In vitro biochemical assays (strand exchange, D-loop, ATPase), single-molecule imaging, co-immunoprecipitation, DNA fiber assay\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro reconstitution with purified proteins, single-molecule imaging, multiple functional assays\",\n      \"pmids\": [\"33453169\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"RAD51 uses its strand exchange activity to bypass the CMG replicative helicase (which remains bound to the stalled fork) during replication fork reversal. RAD51 creates a parental DNA duplex behind the helicase that is then used as substrate by DNA translocases for branch migration to generate a reversed fork. RAD51 is not required for fork reversal when the helicase is unloaded.\",\n      \"method\": \"Auxin-inducible degron system for helicase unloading, DNA fiber assay, epistasis analysis, in vivo genetic experiments\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — inducible protein depletion system, epistasis, mechanistic model with multiple supporting experiments\",\n      \"pmids\": [\"37104614\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"MDC1 forms a direct complex with Rad51 through the forkhead-associated domain of MDC1 (not the BRCA1 C-terminal domain). Depletion of MDC1 impairs Rad51 ionizing radiation-induced foci formation, reduces nuclear and chromatin-bound Rad51, and increases Rad51 protein degradation, indicating MDC1 retains Rad51 in chromatin to facilitate homologous recombination.\",\n      \"method\": \"RNAi knockdown, co-immunoprecipitation, immunofluorescence, chromatin fractionation, HR reporter assay\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct interaction mapped by domain, chromatin fractionation, HR reporter, multiple orthogonal methods\",\n      \"pmids\": [\"16186822\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The MMS22L-TONSL heterodimer localizes to replication forks, associates with RPA-coated ssDNA, and the MMS22L subunit directly interacts with RAD51. Recombinant MMS22L-TONSL limits RAD51 assembly on dsDNA, stimulates RAD51-ssDNA nucleoprotein filament formation, and stimulates RAD51-dependent strand exchange activity in vitro, similar to BRCA2.\",\n      \"method\": \"In vitro biochemical reconstitution, strand exchange assay, co-immunoprecipitation, chromatin immunoprecipitation, DNA fiber assay\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro reconstitution with purified proteins plus in vivo validation, multiple orthogonal methods\",\n      \"pmids\": [\"27797818\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Yeast Rad51 prevents Rad52-mediated annealing of complementary ssDNA in an ATP-dependent manner through a specific interaction between Rad51 and Rad52. The Rad51 nucleoprotein filament is even more effective at inhibiting Rad52-mediated annealing than free Rad51, allowing Rad51 to channel processed DSBs toward strand invasion rather than ssDNA annealing.\",\n      \"method\": \"In vitro ssDNA annealing assays, protein-protein interaction assays with purified yeast proteins\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with purified proteins, mechanistic pathway channeling demonstrated\",\n      \"pmids\": [\"18337252\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Efficient Rad51 turnover from dsDNA (the product of strand exchange) requires both Rad51 ATPase activity and Rad54 ATPase activity. The Rad51-K191R Walker box mutant shows increased filament stability on DNA and defects in DNA binding, but once formed the filaments appear normal by EM; Rad54 ATPase is stimulated by partial Rad51 filaments on dsDNA.\",\n      \"method\": \"ATPase kinetics, electron microscopy of filaments, Rad51-K191R site-directed mutagenesis, DNA binding assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution, mutagenesis, EM, kinetic analysis\",\n      \"pmids\": [\"17567608\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"RPA has a critical postsynaptic role in Rad51-mediated DNA strand exchange: RPA stabilizes Rad51-generated DNA pairing intermediates by binding the displaced ssDNA strand, removing it from Rad51 filaments. Under conditions minimizing ssDNA secondary structure, RPA has little effect on Rad51 filament formation, demonstrating the postsynaptic stabilization is its primary stimulatory function.\",\n      \"method\": \"In vitro strand exchange assays, deproteinization controls, comparison with exonuclease VII as displaced-strand sink\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mechanistically dissected pre- vs post-synaptic RPA roles using purified components and functional controls\",\n      \"pmids\": [\"12169690\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"In budding yeast, Rad51 is phosphorylated on Ser192 in response to DNA damage, primarily mediated by the checkpoint kinase Mec1. Mutating Ser192 to Ala or Glu confers hypersensitivity to DNA damage and homologous recombination defects; Ser192 is required for Rad51 ATPase activity and DNA-binding activity in vitro but not for multimer formation.\",\n      \"method\": \"In vitro kinase assay, ATPase assay, DNA binding assay, site-directed mutagenesis, survival assay, HR assay\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro biochemical characterization of phosphosite mutants plus in vivo genetic phenotypes\",\n      \"pmids\": [\"21738226\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Human Rad51 significantly stimulates the Holliday junction branch migration activity of human Rad54 through specific protein-protein interactions. The stimulation is evolutionarily conserved (also seen with yeast proteins), and the active (ATP-bound) conformation of the Rad51 filament is more stimulatory than the inactive form.\",\n      \"method\": \"In vitro Holliday junction branch migration assay with purified human and yeast proteins, protein-protein interaction assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro, conserved across species, mechanism linked to Rad51 conformation state\",\n      \"pmids\": [\"18617519\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Human Rad51 L1 loop residue Tyr232 is critical for DNA binding: alanine substitution at Tyr232 significantly decreases DNA-binding ability without affecting protein folding or DNA-independent ATPase activity. The L2 loop is also close to the DNA-binding site as shown by fluorescence changes upon DNA binding.\",\n      \"method\": \"Site-directed mutagenesis, gel retardation assay, DNA-dependent ATPase assay, fluorescence spectroscopy\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis combined with multiple in vitro functional assays on purified human Rad51\",\n      \"pmids\": [\"16780572\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"ATP and Mg2+ binding induces a conformational change in Rad51 (detected by CD spectroscopy) that stabilizes the protein in an active DNA-binding-competent state. Rad51 binds ATP with a Kd of ~21 μM in a 1:1 stoichiometry, and DNA binding significantly increases Rad51's affinity for ATP.\",\n      \"method\": \"Circular dichroism spectroscopy, equilibrium dialysis, nucleotide competition binding, ATPase assay\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multiple biophysical methods on purified Rad51 defining conformational change upon nucleotide binding\",\n      \"pmids\": [\"9718317\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"HOP2-MND1 heterodimer acts as a 'molecular trigger' of RAD51 DNA strand exchange by inducing conformational changes in RAD51 that enhance its interaction with nucleotide cofactors, modify its DNA-binding specificity (restricting RAD51 to ssDNA during filament formation, then promoting dsDNA binding during homology search), and enable RAD51 strand exchange in the absence of divalent metal ions normally required for ATP binding.\",\n      \"method\": \"In vitro biochemical reconstitution, strand exchange assay, nucleotide binding assay, ATPase assay with purified proteins\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution with purified proteins, multiple in vitro assays defining mechanistic changes in RAD51 properties\",\n      \"pmids\": [\"24943459\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"RAD51 nucleoprotein filaments specifically recognize and protect abasic sites in ssDNA, which increase RAD51 association rate to DNA. In the absence of BRCA2 or RAD51, abasic ssDNA gaps accumulate and make replicating DNA sensitive to APE1. RAD51 assembled on abasic DNA prevents abasic site cleavage by the MRE11-RAD50 complex, suppressing replication fork breakage.\",\n      \"method\": \"Cryo-electron microscopy, Xenopus laevis egg extract reconstitution, human cell experiments, DNA fiber assay\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — cryo-EM structural data plus functional reconstitution in egg extracts and human cells, multiple orthogonal methods\",\n      \"pmids\": [\"39178838\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"BRCA2 C-terminal TR2 motif binds across the protomer interface in RAD51 filaments, acting as a brace for adjacent RAD51 molecules. TR2 targets an acidic-patch motif on human RAD51 that serves as a recruitment hub for recombination mediators. Structure-guided mutagenesis confirms TR2 stabilizes RAD51 nucleoprotein filaments.\",\n      \"method\": \"Cryo-electron microscopy, structure-guided mutagenesis, biochemical validation\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — cryo-EM structure with mutagenesis validation defines structural basis of filament stabilization\",\n      \"pmids\": [\"37919288\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"BRCA2 accelerates nucleation of RAD51 on RPA-coated ssDNA to rates approaching RAD51 association to naked ssDNA, overcoming the kinetic block imposed by RPA. BRCA2 chaperrones a short pre-assembled RAD51 filament onto RPA-coated ssDNA, eliminating the need for rate-limiting de novo nucleation. A dimer of RAD51 is minimally required for spontaneous nucleation, but growth self-terminates below the diffraction limit.\",\n      \"method\": \"Single-molecule imaging, microfluidics, micromanipulation with full-length BRCA2 and RAD51 on individual DNA molecules\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — single-molecule reconstitution with full-length purified proteins, direct kinetic measurement of nucleation events\",\n      \"pmids\": [\"36976771\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TOPORS functions as a SUMO E3 ligase that SUMOylates RAD51 at lysine residues 57 and 70 in response to DNA damage. ATM-induced phosphorylation of TOPORS at Thr515 facilitates this SUMOylation. SUMOylation-deficient RAD51 shows reduced association with BRCA2 and impaired chromatin loading and HR repair.\",\n      \"method\": \"Co-immunoprecipitation, SUMO assay, site-directed mutagenesis, chromatin fractionation, HR reporter assay\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — identification of writer (TOPORS), modification sites (K57/K70), upstream kinase (ATM/TOPORS), and functional consequence (BRCA2 interaction, chromatin loading)\",\n      \"pmids\": [\"35061896\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Cryo-EM structures of Rad51-DNA and Dmc1-DNA complexes reveal that V273 and D274 in the Loop2 region of human RAD51 (corresponding to P274 and G275 of hDMC1) are key residues controlling mismatch tolerance during strand exchange: RAD51 does not permit HR with mismatches whereas DMC1 can tolerate certain mismatches due to differences in Loop2 interactions with the complementary strand.\",\n      \"method\": \"Cryo-EM structural determination, molecular dynamics simulation, single-molecule FRET, site-directed mutagenesis\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — cryo-EM structure combined with MD simulation, smFRET, and mutagenesis identifying specific residues\",\n      \"pmids\": [\"34871438\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Rad51 accumulates at UV-irradiated, selectively damaged, halogenated-thymidine-labeled chromatin in human fibroblasts, demonstrating redistribution of Rad51 from pre-existing nuclear foci to sites of DNA damage. Rad51 foci preferentially associate with postreplicative (not replicating) chromatin during S phase.\",\n      \"method\": \"UV microirradiation of nuclear areas, immunofluorescence, double-labeling with halogenated thymidine analogs\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct localization experiment with functional context (damage-site redistribution), dual-label approach\",\n      \"pmids\": [\"10908572\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Human RAD51 paralogs (XRCC2, XRCC3, Rad51B, Rad51C, Rad51D) engage in simultaneous protein-protein interactions: Rad51B enhances binding of Rad51C to XRCC3 and to Rad51D; Rad51C allows indirect interaction of Rad51B with Rad51D. Pull-down with 6xHis-tagged baculovirus-expressed proteins confirms Rad51B interacts with Rad51D only when Rad51C is simultaneously expressed.\",\n      \"method\": \"Yeast two-hybrid, yeast three-hybrid, baculovirus co-expression with His-tag pulldown\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — yeast two/three-hybrid plus baculovirus pulldown, interactions confirmed by orthogonal methods in same study\",\n      \"pmids\": [\"10749867\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Mammalian Rad51 and Rad52 colocalize in distinct nuclear foci after DNA damage in murine cells expressing GFP-Rad52, providing evidence of coordinated in vivo function. Cells expressing GFP-Rad52 show increased survival and increased number of Rad51 foci after damage.\",\n      \"method\": \"Live-cell fluorescence microscopy, immunofluorescence colocalization, survival assay in murine cells\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct colocalization by live imaging with functional survival readout, single lab\",\n      \"pmids\": [\"11256631\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Human PSF directly interacts with RAD51 via its N-terminal region and has dual effects on RAD51-mediated homologous pairing and strand exchange: it enhances these activities at low RAD51 concentrations but inhibits them at optimal RAD51 concentrations.\",\n      \"method\": \"Co-immunoprecipitation, in vitro homologous pairing and strand exchange assays, deletion analysis with purified proteins\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct interaction mapped to domain plus functional in vitro assays, single lab\",\n      \"pmids\": [\"19447914\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"HsRad51 is proteolytically cleaved during apoptosis in T-lymphocyte cell lines with kinetics similar to PARP cleavage; cleavage is abolished by the caspase inhibitor Ac-DEVD-CHO but cannot be replicated by purified caspases 2, 3, or 6-10, indicating cleavage by an unidentified Ac-DEVD-CHO-sensitive protease.\",\n      \"method\": \"Immunoblotting of apoptotic cell lysates, cell-free caspase cleavage assay, caspase inhibitor treatment\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — cell-based and cell-free apoptosis assays with pharmacological inhibitor, responsible protease not fully identified\",\n      \"pmids\": [\"9607320\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"The HsRAD51B-HsRAD51C heterodimer forms a stable complex on ssDNA and partially stabilizes the HsRAD51 nucleoprotein filament against BLM-mediated disassembly. HsRAD51B-HsRAD51C also stimulates HsRAD51-mediated D-loop formation in the presence of RPA, but does not facilitate HsRAD51 nucleation on RPA-coated ssDNA.\",\n      \"method\": \"In vitro biochemical assays: ssDNA binding, D-loop assay, filament stability assay against BLM helicase, with purified proteins\",\n      \"journal\": \"DNA repair\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vitro reconstitution with purified human proteins, multiple assays but single lab\",\n      \"pmids\": [\"23810717\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Using single-molecule imaging, Srs2 is shown to be a processive translocase that strips thousands of Rad51 monomers from ssDNA at ~50 monomers/s. Srs2 is recruited to RPA clusters embedded between Rad51 filaments, and multimeric arrays of Srs2 assemble via iterative loading at Rad51-cleared sites. Srs2 also disrupts heteroduplex DNA joints through two alternative pathways.\",\n      \"method\": \"Single-molecule fluorescence imaging, ssDNA curtains, Rad51 filament disruption assay\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — single-molecule reconstitution quantifying translocation rate and mechanism of filament disruption\",\n      \"pmids\": [\"29241544\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"RAD51 Cys319 is a nucleophilic, functionally significant cysteine important for irradiation-induced RAD51 foci formation and HR repair. PRDX1 maintains Cys319 in a reduced state; loss of PRDX1 leads to Cys319 sulfenylation and disrupted RAD51 foci formation. Molecular dynamics simulations show oxidized Cys319 causes dissociation of DNA from the RAD51 filament.\",\n      \"method\": \"Site-directed mutagenesis, PRDX1 knockout cells, molecular dynamics simulation, sulfenylation probe (DAz-2), immunofluorescence, HR reporter assay\",\n      \"journal\": \"Redox biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — mutagenesis plus redox proteomics and MD simulation, functional HR assay, single lab\",\n      \"pmids\": [\"36058112\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In vivo single-molecule tracking of fully functional tagged Rad51 in budding yeast shows that Rad51-ssDNA nucleoprotein filaments span the whole nucleus and are highly dynamic, undergoing cycles of compaction and extension that constitute a robust homology search strategy. Rad54 and Srs2 modulate filament shape and dynamics in vivo.\",\n      \"method\": \"In vivo single-molecule fluorescence microscopy with functional tagged Rad51, DSB induction, genetic analysis with rad54 and srs2 mutants\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — first fully functional tagged Rad51 enabling direct in vivo filament dynamics measurement, supported by biophysical modeling\",\n      \"pmids\": [\"37605042\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Human centromeres harbor enriched DNA breaks that are resolved by RAD51 recombinase during quiescence, safeguarding centromere specification. Centromeric DNA breaks are induced de novo during quiescence and are enzymatically repaired by RAD51.\",\n      \"method\": \"Single-cell imaging strategy for DNA breaks at repetitive regions, RAD51 depletion experiments, quiescent cell analysis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct imaging with RAD51 depletion demonstrating functional role at centromeres, but mechanism details limited\",\n      \"pmids\": [\"36702125\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Conditional deletion of RAD51 in germ cells causes spermatogonial loss and Sertoli cell-only syndrome; inducible RAD51 knockout in adult mice causes defects in meiosis with accumulated meiotic DSBs, reduced pachytene spermatocytes, and less crossover formation, establishing an essential role for RAD51 in spermatogonial maintenance and meiotic progression.\",\n      \"method\": \"Conditional knockout mouse model (Vasa-Cre and UBC-CreERT2), histology, γH2AX immunostaining, crossover analysis\",\n      \"journal\": \"Cell death discovery\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean conditional KO with specific cellular phenotypes in two independent Cre systems\",\n      \"pmids\": [\"35292640\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"FIRRM interacts with and stabilizes the AAA+ ATPase FIGNL1; inactivation of either FIRRM or FIGNL1 causes prolonged RAD51 accumulation at nuclear foci, impaired replication fork dynamics, and UFB formation, demonstrating that FIRRM-FIGNL1 regulates RAD51 dynamics at replication forks.\",\n      \"method\": \"Genome-wide loss-of-function screen, co-immunoprecipitation, immunofluorescence, DNA fiber assay\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — co-IP plus functional RAD51 foci and fiber assays, mechanistic link between FIRRM-FIGNL1 and RAD51 dynamics\",\n      \"pmids\": [\"37347663\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Triplex-induced recombination in human cell-free extracts is dependent on HsRad51: immunodepletion of HsRad51 diminishes triplex-induced recombination, and supplementation with purified HsRad51 partially restores it.\",\n      \"method\": \"Human cell-free extract recombination assay, immunodepletion, protein supplementation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — immunodepletion/reconstitution in cell-free system establishes requirement for HsRad51 in triplex-induced recombination\",\n      \"pmids\": [\"11278954\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"RADX condenses ssDNA filaments into higher-order assemblies that can capture ssDNA in trans, even when the ssDNA is coated with RPA at physiological protein ratios. RADX blocks RPA displacement by RAD51 and prevents RAD51 loading on ssDNA by condensing the ssDNA substrate.\",\n      \"method\": \"Single-molecule imaging of purified proteins, ssDNA curtains, RADX-RPA-RAD51 competition assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — single-molecule reconstitution with purified proteins revealing mechanism of RADX inhibition of RAD51\",\n      \"pmids\": [\"32621611\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RAD51 is an ATPase recombinase that assembles into nucleoprotein filaments on ssDNA in an ATP-dependent manner (stabilized by ATP binding-induced conformational changes at specific residues including L1 loop Tyr232 and Cys319), searches for and invades homologous dsDNA via strand exchange to drive homologous recombination repair of DSBs and protect stalled replication forks; filament formation is positively regulated by BRCA2 (which nucleates RAD51 on RPA-coated ssDNA by chaperoning preassembled RAD51 onto substrate), the RAD51 paralogs (which remodel filaments to a stabilized open conformation), HOP2-MND1 (which triggers RAD51 conformational changes enhancing nucleotide and DNA binding), and MMS22L-TONSL (which limits dsDNA binding and promotes ssDNA filament formation), while being negatively regulated by RADX (which competes for ssDNA, stimulates RAD51 ATPase, and destabilizes filaments) and Srs2 (which processively strips RAD51 from ssDNA); RAD51 filament stability and chromatin recruitment are further modulated by post-translational modifications including PLK1-mediated phosphorylation at Ser14 (promoted by TOPBP1), TOPORS-mediated SUMOylation at Lys57/70 (required for BRCA2 interaction and chromatin loading), and redox regulation of Cys319 by PRDX1; additionally, RAD51 uses its strand exchange activity to bypass the CMG helicase during fork reversal, protects abasic sites from MRE11-RAD50 cleavage, and in meiosis cooperates with or acts independently of DMC1 at distinct DSB end positions.\"\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1994,\n      \"finding\": \"Human RAD51 protein binds single- and double-stranded DNA, exhibits DNA-dependent ATPase activity, underwinds duplex DNA in an ATP-dependent reaction, and forms helical nucleoprotein filaments on nicked duplex DNA resembling RecA/yeast Rad51 filaments, establishing it as a functional RecA homolog.\",\n      \"method\": \"Protein purification, ATPase assay, topological unwinding assay, electron microscopy\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution with purified protein, multiple orthogonal biochemical methods\",\n      \"pmids\": [\"7988572\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Human RAD51 promotes ATP-dependent homologous pairing and strand exchange reactions in vitro; joint molecule formation requires ATP hydrolysis and DNA homology and is stimulated by RPA; hRad51 initiates strand exchange but requires additional proteins for extensive heteroduplex formation.\",\n      \"method\": \"In vitro strand exchange assay with purified proteins, ATP hydrolysis measurement\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro strand exchange with purified human RAD51\",\n      \"pmids\": [\"8929543\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Human RAD51 (HsRad51) promotes homologous pairing and strand exchange at rates less than 1/10 those of RecA; in the presence of ATP-γ-S, HsRad51 forms stable presynaptic complexes and promotes renaturation but not strand exchange or homologous pairing with duplex DNA, suggesting homologous pairing and strand exchange are more closely linked to ATP hydrolysis in HsRad51 than in RecA.\",\n      \"method\": \"In vitro recombination assays, ATP hydrolysis assays, stoichiometry of DNA binding\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — rigorous in vitro biochemistry with purified human RAD51, multiple assay types\",\n      \"pmids\": [\"9012806\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"BRCA1 colocalizes with RAD51 in discrete nuclear foci during S phase and the two proteins co-immunoprecipitate; BRCA1 residues 758–1064 form RAD51-containing complexes in vitro; both proteins associate with developing synaptonemal complexes in meiotic cells, indicating a functional interaction in DNA repair and recombination.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence co-localization, in vitro binding, meiotic chromosome spreads\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal co-IP plus in vitro binding, replicated in multiple cellular contexts\",\n      \"pmids\": [\"9008167\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"RAD51 interacts specifically with the eight BRC motifs encoded in exon 11 of BRCA2; RAD51 residues 98–339 are sufficient to interact with the 59-residue minimal conserved BRC motif, mapping the molecular interface between RAD51 and BRCA2.\",\n      \"method\": \"Yeast two-hybrid, biochemical deletion analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — yeast two-hybrid plus biochemical mapping, foundational interaction study\",\n      \"pmids\": [\"9405383\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"BRCA2 protein physically interacts with RAD51 during mouse embryogenesis; Brca2-deficient embryos show developmental arrest and radiation hypersensitivity mediated by RAD51, indicating BRCA2 is an essential cofactor in RAD51-dependent repair of double-strand breaks.\",\n      \"method\": \"Co-immunoprecipitation, mouse knockout, radiation sensitivity assay\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis in mouse model plus co-IP, replicated across labs\",\n      \"pmids\": [\"9126738\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"ATP and Mg2+ binding induces a conformational change in Rad51 detected by circular dichroism spectroscopy, producing a more structured state; this active conformation is required for DNA binding; ATP-γ-S also stabilizes activity but AMP-PNP does not, and DNA significantly increases Rad51's affinity for ATP.\",\n      \"method\": \"Equilibrium dialysis (nucleotide binding), circular dichroism spectroscopy, thermal inactivation assay\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multiple biophysical methods with purified protein establishing mechanistic conformational change\",\n      \"pmids\": [\"9718317\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"BRCA2 gene product forms in vivo complexes with both p53 and RAD51 as a nuclear phosphoprotein; exogenous BRCA2 inhibits p53 transcriptional activity and RAD51 co-expression enhances this effect, placing BRCA2 at the intersection of cell cycle control and DNA repair via RAD51.\",\n      \"method\": \"Co-immunoprecipitation in vivo, nuclear fractionation, transcriptional reporter assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo co-IP plus functional reporter, single lab study\",\n      \"pmids\": [\"9811893\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"RAD51 accumulates at sites of UV-induced DNA damage in human S-phase cells and is preferentially associated with postreplicative (rather than actively replicating) chromatin, demonstrating that RAD51 redistribution to damaged chromatin occurs from pre-existing S-phase foci.\",\n      \"method\": \"UV microirradiation, BrdU/IdU dual-label fractionation, immunofluorescence microscopy\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct localization with functional context, multiple imaging approaches\",\n      \"pmids\": [\"10908572\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Human RAD51 paralogs XRCC2, XRCC3, RAD51B, RAD51C, and RAD51D form simultaneous protein interactions; yeast three-hybrid experiments show several pairs interact concurrently (e.g., RAD51B enhances RAD51C binding to XRCC3 and RAD51D); baculovirus co-expression confirms multi-subunit complex formation, suggesting these paralogs assemble into one or more complexes.\",\n      \"method\": \"Yeast two-hybrid, yeast three-hybrid, His-tag pull-down from baculovirus co-expression\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal interaction methods, simultaneous complex formation demonstrated\",\n      \"pmids\": [\"10749867\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Gamma-H2AX phosphorylation after DNA double-strand breaks is necessary for recruitment of RAD51 (and RAD50, BRCA1) to nuclear foci; wortmannin (PI-3 kinase inhibitor) prevents gamma-H2AX formation and abolishes RAD51 focus formation, placing PI-3 kinase signaling and H2AX upstream of RAD51 recruitment.\",\n      \"method\": \"Immunofluorescence, wortmannin inhibition, laser-induced DSBs in human cells\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — epistasis via chemical inhibition plus co-localization, foundational study with wide replication\",\n      \"pmids\": [\"10959836\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Mammalian Rad51 and Rad52 co-localize in distinct nuclear foci upon DNA damage in murine cells expressing GFP-Rad52; cells expressing GFP-Rad52 show increased survival and increased Rad51 foci, indicating Rad52 is limiting for Rad51-mediated repair and the two proteins function together in the DNA damage response.\",\n      \"method\": \"GFP-Rad52 live-cell imaging, immunofluorescence, survival assay\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct co-localization with functional consequence, single-lab study\",\n      \"pmids\": [\"11256631\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"BRCA2 plays a dual role in regulating RAD51: BRC3 and BRC4 repeats block RAD51 nucleoprotein filament formation; cancer-associated BRC3 mutations abolish this effect; additionally, BRCA2 controls nuclear import of RAD51, with a cancer-associated BRCA2 truncation causing defective nuclear RAD51 localization.\",\n      \"method\": \"In vitro filament formation assays, nuclear transport assays, cancer mutation analysis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution plus mutagenesis plus cellular localization with cancer-relevant mutations\",\n      \"pmids\": [\"11239456\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"HsRad51 is required for triplex-induced intermolecular recombination between plasmid targets in human cell-free extracts; depletion of HsRad51 with specific antibodies diminishes triplex-induced recombination and supplementation with purified HsRad51 restores it.\",\n      \"method\": \"Cell-free extract reconstitution, antibody depletion, purified protein supplementation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — cell-free reconstitution with depletion/add-back, but single lab\",\n      \"pmids\": [\"11278954\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Crystal structure of a BRC repeat–RAD51 RecA-homology domain complex reveals that the BRC repeat mimics the RAD51 oligomerization interface, enabling BRCA2 to control RAD51 nucleoprotein filament assembly; cancer-associated BRC mutations disrupt predicted RAD51 contacts.\",\n      \"method\": \"X-ray crystallography, structure-guided mutational analysis\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — high-resolution crystal structure plus cancer mutation interpretation\",\n      \"pmids\": [\"12442171\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Human Rad54 promotes transient strand separation in duplex DNA via ATP hydrolysis-driven DNA supercoiling; its ATPase, supercoiling, and strand-opening activities are greatly stimulated by interaction with hRad51; hRad51 and hRad54 functionally cooperate in the homologous DNA pairing reaction.\",\n      \"method\": \"In vitro ATPase assay, DNA supercoiling assay, strand opening assay, homologous pairing assay with purified proteins\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multiple in vitro reconstitution assays with purified human proteins\",\n      \"pmids\": [\"12205100\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"FANCD2 co-localizes with RAD51 in S-phase-specific nuclear foci upon DNA damage; monoubiquitination of FANCD2 is required for this co-localization and for normal cell-cycle progression after mitomycin C exposure, placing FANCD2 in the same S-phase repair pathway as RAD51.\",\n      \"method\": \"Immunofluorescence co-localization, cell-cycle fractionation, FA mutant cell analysis\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — co-localization with genetic evidence from FA mutant cells, single lab\",\n      \"pmids\": [\"12239151\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"RPA stabilizes RAD51-generated DNA pairing intermediates in a critical postsynaptic role during strand exchange; RPA binds the displaced strand to stabilize pairing, whereas its presynaptic role in facilitating filament formation is minimal under conditions that minimize ssDNA secondary structure.\",\n      \"method\": \"In vitro strand exchange assay with purified Rad51 and RPA, deproteinization controls\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mechanistic dissection of pre- vs. post-synaptic RPA roles using purified proteins\",\n      \"pmids\": [\"12169690\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Yeast DNA helicase Srs2 binds Rad51, possesses robust ssDNA-stimulated ATPase activity, and at catalytic quantities causes severe inhibition of Rad51-mediated recombination by dislodging Rad51 from ssDNA, thereby dismantling the presynaptic filament.\",\n      \"method\": \"In vitro ATPase assay, Rad51 filament disruption assay, pulldown\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro with purified proteins, mechanistic demonstration of filament dismantling\",\n      \"pmids\": [\"12748644\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Rad52 forms complexes with Rad51, RPA, and Rad59; Rad51-Rad52-Rad59 and RPA-Rad52-Rad59 complexes depend on Rad52 for formation; the N-terminal Rad52 self-interaction domain is required for Rad59 interaction, implicating distinct Rad52 complexes in conservative and single-strand annealing recombination pathways.\",\n      \"method\": \"Co-immunoprecipitation, two-hybrid, in vitro binding\",\n      \"journal\": \"DNA repair\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple interaction methods, mechanistic pathway placement\",\n      \"pmids\": [\"13679150\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"RAD51 focus formation in response to ionizing radiation is dependent on BRCA2 and the five RAD51 paralogs (RAD51B, RAD51C, RAD51D, XRCC2, XRCC3), whereas spontaneous S-phase RAD51 foci form without requiring these factors, revealing two distinct modes of RAD51 nuclear focus assembly.\",\n      \"method\": \"Immunofluorescence in paralog/BRCA2-deficient cell lines, DNA damage-induced focus assay\",\n      \"journal\": \"Philosophical transactions of the Royal Society of London. Series B, Biological sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis using defined mutant cell lines, replicated across multiple paralog mutants\",\n      \"pmids\": [\"15065660\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"BRCA2 BRC repeats (BRC3/BRC4) at low concentrations bind and form stable complexes with RAD51-DNA nucleoprotein filaments; BRC3 contacts the N-terminal domain of RAD51 while BRC4 contacts the nucleotide-binding core, demonstrating nonequivalent and distinct binding modes within the filament.\",\n      \"method\": \"Electron microscopy of RAD51-DNA filaments with BRC peptides, cryo-EM image reconstruction\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — structural analysis by EM with domain mapping of two distinct binding sites\",\n      \"pmids\": [\"15937124\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"CDK-mediated phosphorylation of BRCA2 at serine 3291 during late cell cycle blocks the C-terminal BRCA2–RAD51 interaction; this phosphorylation is low in S phase when recombination is active and increases toward mitosis; DNA damage decreases S3291 phosphorylation to re-enable RAD51 binding, providing a molecular switch for recombination regulation.\",\n      \"method\": \"Phospho-specific antibody, cell-cycle fractionation, in vitro kinase assay, co-immunoprecipitation\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — identified PTM writer (CDK), mapped site, functional consequence of phosphorylation on RAD51 interaction\",\n      \"pmids\": [\"15800615\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Chk1 interacts with RAD51 and phosphorylates RAD51 on Thr309 in a Chk1-dependent manner; loss of Chk1 by siRNA or chemical inhibition abolishes RAD51 focus formation after hydroxyurea; a phosphorylation-deficient RAD51(T309A) mutant causes hydroxyurea hypersensitivity, establishing Chk1 as a regulator of RAD51-mediated homologous recombination repair.\",\n      \"method\": \"Co-immunoprecipitation, phospho-specific antibody, siRNA, chemical inhibitors, RAD51-T309A mutant phenotyping\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — PTM identified (writer: Chk1, site: T309), mutagenesis of phosphosite, epistatic loss-of-function\",\n      \"pmids\": [\"15665856\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"BRCA2 and BRCA1 form a stable biochemical complex that co-localizes with RAD51 at replication sites after hydroxyurea or UV damage in S-phase cells and on synaptonemal complexes in meiosis, placing both tumor suppressors together in the same RAD51-mediated repair pathway.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence co-localization, meiotic chromosome spreads\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo complex formation plus co-localization in multiple cell contexts, replicated\",\n      \"pmids\": [\"9774970\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"MDC1 directly interacts with RAD51 through its forkhead-associated (FHA) domain; MDC1 knockdown impairs RAD51 focus formation after ionizing radiation, reduces nuclear and chromatin-bound RAD51, and increases RAD51 protein degradation, indicating MDC1 retains RAD51 in chromatin to facilitate homologous recombination.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, chromatin fractionation, immunofluorescence\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct interaction mapped to domain, multiple functional consequences of depletion\",\n      \"pmids\": [\"16186822\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"The L1 loop residue Tyr232 of human RAD51 is critical for DNA binding; alanine or conservative tryptophan substitution significantly decreases DNA-binding ability without affecting protein folding or salt-induced ATPase; fluorescence spectroscopy confirms L1 and L2 loops are positioned near the DNA-binding site.\",\n      \"method\": \"Site-directed mutagenesis, gel retardation assay, DNA-dependent ATPase assay, fluorescence spectroscopy\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — active-site mutagenesis with multiple functional readouts\",\n      \"pmids\": [\"16780572\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Both Rad51 ATPase activity and Rad54 ATPase activity are required for efficient Rad51 turnover from dsDNA (product dissociation); the Rad54 ATPase is stimulated by partial Rad51 filaments on dsDNA; the Rad51-K191R Walker-box mutant has increased filament stability and defective dsDNA binding, demonstrating that Rad51's own ATPase activity is needed for normal presynaptic and postsynaptic filament dynamics.\",\n      \"method\": \"In vitro ATPase kinetics, electron microscopy of filaments, Walker-box mutant analysis\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro with mutant and WT proteins, mechanistic dissection of two ATPases\",\n      \"pmids\": [\"17567608\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Human Rad51 specifically inhibits Rad52-mediated annealing of complementary ssDNA in an ATP-dependent manner via a direct Rad51–Rad52 interaction; the Rad51 nucleoprotein filament is more inhibitory than free Rad51; Rad59 partially restores Rad52-dependent annealing in the presence of Rad51, suggesting Rad51 channels repair toward strand invasion over annealing.\",\n      \"method\": \"In vitro ssDNA annealing assay, protein interaction analysis, ATP dependency experiments\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro biochemistry with purified yeast proteins, multiple conditions tested\",\n      \"pmids\": [\"18337252\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Human Rad51 stimulates branch migration activity of human Rad54 through specific protein–protein interactions; the active (ATP-bound) Rad51 filament conformation is more stimulatory than the inactive form; this stimulation is evolutionarily conserved (also seen with yeast proteins), indicating Rad51 allosterically regulates Rad54's branch migration function.\",\n      \"method\": \"In vitro branch migration assay, protein–protein interaction analysis, yeast and human protein comparison\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro, mechanistic demonstration of allosteric stimulation, confirmed in two species\",\n      \"pmids\": [\"18617519\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Human PSF directly interacts with RAD51 via its N-terminal region and modulates RAD51 activity in a concentration-dependent manner: PSF enhances RAD51-mediated homologous pairing and strand exchange at low RAD51 concentrations but inhibits these activities at optimal RAD51 concentrations, suggesting dual regulatory roles.\",\n      \"method\": \"Co-immunoprecipitation/pulldown, in vitro homologous pairing assay, strand exchange assay, deletion analysis\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro reconstitution with mapped interaction domain, single lab\",\n      \"pmids\": [\"19447914\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Purified full-length BRCA2 binds RAD51 and stimulates RAD51-mediated recombination by: (1) targeting RAD51 to ssDNA over dsDNA, (2) enabling RAD51 to displace RPA from ssDNA, and (3) stabilizing RAD51-ssDNA filaments by blocking ATP hydrolysis. BRCA2 does not directly catalyze ssDNA annealing.\",\n      \"method\": \"Full-length BRCA2 purification, in vitro strand exchange assay, filament stability assay, RPA displacement assay\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — first purification of full-length BRCA2 with reconstituted mechanistic assays, multiple orthogonal methods\",\n      \"pmids\": [\"20729832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"RAD51 mediates two distinct replication responses: stalled replication forks (HU short-term) are restarted in a RAD51-dependent, XRCC3-dependent manner without triggering HR; collapsed forks (prolonged HU) undergo RAD51-dependent HR repair without apparent restart, showing that restart and repair represent distinct RAD51 pathways.\",\n      \"method\": \"DNA fiber assay, siRNA knockdown, XRCC3 mutant cells, RAD51 focus formation\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with multiple mutant lines, fiber assay distinguishing two pathways\",\n      \"pmids\": [\"20188668\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"In budding yeast, Rad51 is phosphorylated on Ser192 primarily by the checkpoint kinase Mec1 in response to DNA damage; Rad51-S192A or S192E mutations confer DNA damage hypersensitivity and HR defects; Ser192 is required for Rad51 ATPase activity and DNA binding in vitro but not for multimer formation.\",\n      \"method\": \"Mass spectrometry phosphosite identification, in vitro kinase assay, HR assay, ATPase assay, DNA binding assay\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — PTM writer (Mec1) identified, site mapped, in vitro biochemical phenotype characterized\",\n      \"pmids\": [\"21738226\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"HOP2-MND1 heterodimer acts as a 'molecular trigger' of RAD51 by inducing conformational changes that enhance RAD51's interaction with nucleotide cofactors, modify DNA-binding specificity, enable strand exchange without divalent metal ions, offset K133A ATP-binding mutation defects, restrict dsDNA binding during filament formation, and promote dsDNA binding during homology search.\",\n      \"method\": \"In vitro strand exchange assay, nucleotide binding assay, ssDNA/dsDNA binding assay with HOP2-MND1 and mutant RAD51\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multiple in vitro reconstitution assays with mechanistic dissection\",\n      \"pmids\": [\"24943459\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"RAD51-mediated replication fork reversal is a global response to diverse genotoxic treatments in human cells; electron microscopy of replication fork architecture shows uncoupling and reversal are frequent; RAD51 is present at replication forks independently of breakage; fork reversal is RAD51-dependent and antagonized by PARP/RECQ1-regulated restart.\",\n      \"method\": \"Electron microscopy of replication fork architecture, siRNA depletion, EM quantification of fork reversal\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — direct EM visualization of fork structures plus RAD51 depletion, global genotoxic treatment panel\",\n      \"pmids\": [\"25733714\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The C. elegans Rad51 paralog complex RFS-1/RIP-1 binds and remodels pre-synaptic RAD-51-ssDNA filaments into a stabilized, 'open,' flexible conformation in which ssDNA is more accessible and RAD-51 dissociation rate is reduced; Walker-box mutations in RFS-1 abolish filament remodeling and fail to stimulate strand exchange, demonstrating remodeling is essential for paralog function.\",\n      \"method\": \"Single-molecule FRET, electron microscopy, in vitro strand exchange assay, Walker-box mutagenesis\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multiple orthogonal structural and biochemical methods, mutagenesis validation\",\n      \"pmids\": [\"26186187\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"TOPBP1 promotes PLK1 kinase-mediated phosphorylation of RAD51 at serine 14, a modification required for RAD51 recruitment to chromatin and focus formation; TOPBP1 BRCT domains 7/8 are essential for RAD51 foci; TOPBP1 depletion abrogates RAD51 chromatin loading without affecting upstream resection or RPA loading.\",\n      \"method\": \"siRNA screen, phospho-specific antibody, in vitro kinase assay, chromatin fractionation, BRCT mutants\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — PTM writer (PLK1) identified, site (S14) mapped, upstream regulator (TOPBP1) identified, multiple loss-of-function approaches\",\n      \"pmids\": [\"26811421\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The MMS22L-TONSL heterodimer localizes to replication forks, associates with RPA-coated ssDNA, and directly interacts with RAD51 via MMS22L; recombinant MMS22L-TONSL limits RAD51 assembly on dsDNA, stimulating RAD51-ssDNA filament formation and strand exchange; MMS22L-RAD51 interaction is required for proper RAD51 focus assembly and HR-mediated fork restart.\",\n      \"method\": \"Co-immunoprecipitation, in vitro strand exchange assay with purified proteins, mutant cell analysis, iPOND replication fork proteomics\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro reconstitution plus in vivo epistasis, multiple methods\",\n      \"pmids\": [\"27797818\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Human RAD52 binds tightly to RPA-ssDNA complexes and inhibits RPA turnover; during presynaptic complex assembly, RAD51 displaces most RAD52-RPA from ssDNA; once RAD51 is assembled, it restricts new RAD52 binding events, revealing reciprocal regulation between RAD51 and RAD52 at the presynaptic filament.\",\n      \"method\": \"Single-molecule imaging, ssDNA curtains, TIRF microscopy\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — single-molecule reconstitution of individual protein dynamics on ssDNA\",\n      \"pmids\": [\"28551686\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Srs2 is a processive translocase that strips Rad51 monomers from ssDNA at ~50 monomers/second; Srs2 is recruited to RPA clusters embedded within Rad51 filaments; multi-Srs2 arrays form via iterative loading; Srs2 disrupts heteroduplex DNA joints through two alternative pathways, establishing the mechanism of Srs2-mediated anti-recombination.\",\n      \"method\": \"Single-molecule fluorescence imaging (ssDNA curtains), TIRF microscopy\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — single-molecule visualization of Srs2 acting on Rad51 filaments in real time\",\n      \"pmids\": [\"29241544\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"RADX antagonizes RAD51 at stalled replication forks by competing with RAD51 for ssDNA binding; silencing RADX restores fork protection in BRCA1/2-, FANCA-, FANCD2-, or BOD1L-deficient cells; RADX overexpression causes fork degradation dependent on MRE11 and DNA2 and fork reversal, establishing that the RAD51/RADX balance determines stalled fork fate.\",\n      \"method\": \"DNA fiber assay, siRNA, RADX overexpression, iPOND, fork protection assays\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — epistasis across multiple HR-deficient backgrounds, direct ssDNA competition assay\",\n      \"pmids\": [\"30021152\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"In budding yeast, Rad52–Rad51 protein interaction is dispensable for Rad51 filament formation and gene conversion but is essential for protecting Rad51 filaments against dissociation by Srs2 DNA translocase, revealing a filament-protection function of Rad52–Rad51 association independent of mediator activity.\",\n      \"method\": \"Rad52 interaction-deficient mutants, in vitro Srs2-disruption assay, in vivo gene conversion assay, electron microscopy\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — separation-of-function mutants with in vitro and in vivo validation\",\n      \"pmids\": [\"29985128\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Rad51 and Dmc1 have an intrinsic ability to self-segregate in mixed filaments on ssDNA, even without accessory proteins; Dmc1 stabilizes adjacent Rad51 filament segments, suggesting the two meiotic recombinases form spatially distinct but cross-stabilizing filament domains.\",\n      \"method\": \"Single-molecule imaging (ssDNA curtains), co-visualization of labeled Rad51 and Dmc1\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — single-molecule visualization directly demonstrating self-segregation\",\n      \"pmids\": [\"29382724\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"RADX condenses RPA-coated ssDNA filaments via higher-order assemblies that can capture ssDNA in trans; RADX blocks RPA displacement by RAD51 and prevents RAD51 loading on ssDNA, establishing RADX as an ssDNA condensation protein that inhibits RAD51 filament formation.\",\n      \"method\": \"Single-molecule imaging of RADX on RPA-ssDNA, TIRF microscopy, RAD51 loading assay\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct single-molecule visualization of RADX mechanism at physiological protein ratios\",\n      \"pmids\": [\"32621611\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"RADX directly and selectively interacts with ATP-bound RAD51, stimulates RAD51 ATP hydrolysis, and destabilizes RAD51 nucleofilaments, inhibiting strand exchange and D-loop formation; RADX ssDNA-binding capability plus its RAD51 interaction are both required for maintaining replication fork elongation and stability; BRCA2 can overcome RADX-mediated RAD51 inhibition.\",\n      \"method\": \"In vitro strand exchange assay, ATPase assay, RAD51 filament stability assay, DNA fiber assay, RADX–RAD51 interaction mapping\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro mechanism with purified proteins plus cellular validation\",\n      \"pmids\": [\"33453169\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HELQ helicase activity is strongly stimulated by RAD51 (which forms a complex with HELQ) during DNA unwinding; conversely, RPA inhibits HELQ unwinding but stimulates a previously unappreciated HELQ DNA strand annealing activity; HELQ can capture RPA-bound DNA strands and displace RPA to facilitate annealing.\",\n      \"method\": \"In vitro helicase and annealing assays, single-molecule imaging, biochemical co-complex analysis\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro with single-molecule imaging, mechanistic dissection\",\n      \"pmids\": [\"34937945\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The HsRAD51B-HsRAD51C heterodimer forms stable complexes on ssDNA and partially stabilizes the HsRAD51 nucleoprotein filament against BLM-mediated disruption; it stimulates HsRAD51-mediated D-loop formation in the presence of RPA but does not facilitate HsRAD51 nucleation on RPA-coated ssDNA, placing RAD51B-C function downstream of BRCA2 in filament stabilization during the presynaptic phase.\",\n      \"method\": \"In vitro filament stability assay, D-loop assay, ssDNA binding assay with purified proteins\",\n      \"journal\": \"DNA repair\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro with purified proteins, but single lab, moderate complexity\",\n      \"pmids\": [\"23810717\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Conditional knockout of RAD51 in mouse germ cells (Vasa-Cre) causes spermatogonial loss and Sertoli cell-only syndrome; inducible adult knockout causes meiotic DSB accumulation, reduced pachytene spermatocytes, and fewer crossovers, establishing an essential role for RAD51 in spermatogonial maintenance and meiotic DSB repair.\",\n      \"method\": \"Conditional mouse knockout (Vasa-Cre and UBC-CreERT2), γH2AX staining, crossover quantification\",\n      \"journal\": \"Cell death discovery\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct loss-of-function in vivo with specific molecular phenotypes\",\n      \"pmids\": [\"35292640\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TOPORS acts as a SUMO E3 ligase for RAD51, SUMOylating RAD51 at lysines 57 and 70 in response to DNA damage; SUMOylation is facilitated by ATM-induced phosphorylation of TOPORS at Thr515; SUMOylation-deficient RAD51 (K57R/K70R) reduces chromatin loading, RAD51 focus formation, and association with BRCA2, impairing HR repair.\",\n      \"method\": \"SUMO modification assay, phospho-specific antibody, SUMOylation-deficient mutants, co-immunoprecipitation, HR reporter assay\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — PTM writer (TOPORS), sites (K57, K70) mapped, upstream signal (ATM-TOPORS) identified, functional consequence characterized\",\n      \"pmids\": [\"35061896\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"RAD51 Cys319 is a redox-sensitive residue regulated by PRDX1; oxidation of Cys319 (sulfenylation) impairs irradiation-induced RAD51 focus formation and HR; PRDX1 maintains Cys319 in a reduced state; molecular dynamics simulations show that oxidized Cys319 causes dissociation of DNA from the RAD51 filament.\",\n      \"method\": \"Phospho/sulfenylation probes, PRDX1-deficient cells, RAD51-C319 mutagenesis, molecular dynamics simulation, PARP inhibitor sensitivity\",\n      \"journal\": \"Redox biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — site-specific oxidation mapped, mutagenesis, MD simulation, multiple functional readouts\",\n      \"pmids\": [\"36058112\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Cryo-EM structure of the BRCA2 TR2 motif bound to the human RAD51 nucleoprotein filament reveals TR2 binds across the protomer interface, acting as a brace for adjacent RAD51 molecules; TR2 targets an acidic-patch motif on RAD51 that also serves as a recruitment hub for recombination mediators in fission yeast.\",\n      \"method\": \"Cryo-electron microscopy, structure-guided mutagenesis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — cryo-EM structure plus mutagenesis validation\",\n      \"pmids\": [\"37919288\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Cryo-EM structures of human RAD51-DNA and DMC1-DNA complexes reveal that the Loop2 region (containing ssDNA and complementary strand binding residues) differs between RAD51 and DMC1; RAD51 residues V273 and D274 (vs. P274 and G275 in DMC1) are key determinants of mismatch intolerance during strand exchange, explaining RAD51's high fidelity compared to DMC1's mismatch tolerance.\",\n      \"method\": \"Cryo-EM structure determination, molecular dynamics simulation, single-molecule FRET, mutagenesis\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — cryo-EM structures plus mutagenesis and single-molecule validation\",\n      \"pmids\": [\"34871438\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"RAD51 uses its strand exchange activity to bypass the replicative helicase (CMG) that remains bound at stalled replication forks; when CMG is unloaded, RAD51 is no longer required for fork reversal; RAD51 creates a parental DNA duplex behind the helicase that DNA translocases then use as substrate for branch migration to generate a reversed fork.\",\n      \"method\": \"Auxin-inducible degron to acutely deplete CMG, DNA fiber assay, EM of replication forks, RAD51 strand exchange mutants\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — mechanistic genetic epistasis with CMG depletion, strand exchange–specific mutants, EM visualization\",\n      \"pmids\": [\"37104614\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"BRCA2 chaperones a short preassembled RAD51 filament onto RPA-coated ssDNA; a dimer of RAD51 is the minimal unit for spontaneous nucleation but growth self-terminates below diffraction limit; BRCA2 accelerates RAD51 nucleation to rates approaching binding to naked ssDNA, eliminating the kinetic barrier imposed by RPA.\",\n      \"method\": \"Single-molecule microfluidics with full-length BRCA2, direct visualization of RAD51 filament assembly on RPA-ssDNA\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — single-molecule reconstitution with full-length BRCA2, quantitative kinetic measurements\",\n      \"pmids\": [\"36976771\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Human centromeres harbor enrichment of DNA breaks that occur during both proliferation and quiescence; centromere DNA breaks in quiescent cells are resolved by the RAD51 recombinase, which safeguards functional centromere specification.\",\n      \"method\": \"Single-cell imaging of DNA breaks at repetitive centromere regions, RAD51 depletion, centromere function assay\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct imaging plus RAD51 depletion phenotype, novel cellular context\",\n      \"pmids\": [\"36702125\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Functionally tagged Rad51 in budding yeast forms exceedingly long nucleoprotein filaments spanning the entire nucleus after DSB induction; filaments adopt dynamic compaction-extension cycles modulated by Rad54 (promoting compaction) and Srs2 (promoting extension/disassembly); biophysical modeling shows this dynamics constitutes a robust homology search strategy.\",\n      \"method\": \"Live-cell single-molecule imaging with functional tagged Rad51, biophysical modeling, DSB induction\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — first direct in vivo tracking of functional tagged Rad51 filaments, quantitative biophysical model\",\n      \"pmids\": [\"37605042\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"RAD51 nucleofilaments specifically recognize and protect abasic sites in ssDNA (which increase RAD51's DNA association rate); in the absence of BRCA2 or RAD51, abasic ssDNA gaps accumulate making replicating DNA sensitive to APE1; RAD51 assembled on abasic DNA prevents cleavage by the MRE11-RAD50 complex, suppressing replication fork breakage.\",\n      \"method\": \"Cryo-EM of RAD51 on abasic DNA, Xenopus egg extract assays, human cell experiments, APE1/MRE11 cleavage assays\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — cryo-EM structure revealing abasic site recognition plus reconstituted fork protection assays in two model systems\",\n      \"pmids\": [\"39178838\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RAD51 is a RecA-family ATPase that assembles onto ssDNA to form a nucleoprotein filament—stabilized by BRCA2 (which nucleates the filament and blocks ATP hydrolysis) and regulated by TOPBP1/PLK1-mediated S14 phosphorylation, Chk1-mediated T309 phosphorylation, TOPORS-mediated K57/K70 SUMOylation, CDK-mediated BRCA2-S3291 phosphorylation, and redox control of C319—that catalyzes homology search and ATP-dependent strand exchange with duplex DNA (inhibited by Srs2/RADX, stimulated by Rad54/HOP2-MND1/PSF), and additionally functions in replication fork reversal by using its strand exchange activity to bypass the CMG helicase, in fork protection by shielding nascent DNA and abasic sites from MRE11/RAD50 nucleolytic degradation, and in meiotic DSB repair and spermatogenesis.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"RAD51 is the central eukaryotic recombinase that assembles ATP-dependent nucleoprotein filaments on single-stranded DNA to catalyze homologous pairing and strand exchange, thereby driving homologous recombination repair of DNA double-strand breaks, protecting stalled replication forks, and supporting meiotic progression. RAD51 filament formation on ssDNA is promoted by BRCA2, which chaperones pre-assembled RAD51 onto RPA-coated ssDNA to overcome the kinetic barrier of nucleation [PMID:20729832, PMID:36976771], and is further stabilized by RAD51 paralogs that remodel filaments into an open, active conformation [PMID:26186187] and by the BRCA2 TR2 motif that braces adjacent protomers [PMID:37919288]; conversely, filaments are antagonized by the anti-recombinase Srs2, which processively strips RAD51 from ssDNA [PMID:12748644, PMID:29241544], and by RADX, which competes for ssDNA binding and stimulates RAD51 ATPase-dependent filament destabilization [PMID:30021152, PMID:33453169]. RAD51 strand exchange activity is stimulated by Rad54, which promotes DNA supercoiling and Holliday junction branch migration through direct RAD51 interaction [PMID:9590697, PMID:18617519], and by HOP2-MND1, which triggers conformational changes that enhance nucleotide and DNA binding specificity [PMID:24943459]; filament function and chromatin recruitment are regulated by post-translational modifications including PLK1-mediated Ser14 phosphorylation [PMID:26811421], TOPORS-mediated SUMOylation at Lys57/70 required for BRCA2 interaction [PMID:35061896], and PRDX1-dependent redox maintenance of Cys319 [PMID:36058112]. Beyond canonical DSB repair, RAD51 uses its strand exchange activity to bypass the CMG helicase during replication fork reversal [PMID:37104614], protects abasic sites from MRE11-RAD50 nucleolytic cleavage [PMID:39178838], and is essential for spermatogonial maintenance and meiotic crossover formation [PMID:35292640].\",\n  \"teleology\": [\n    {\n      \"year\": 1997,\n      \"claim\": \"Establishing that human RAD51 possesses intrinsic strand exchange activity answered whether the bacterial RecA paradigm is conserved in humans, but revealed that human RAD51 is substantially slower and more tightly coupled to ATP hydrolysis than RecA.\",\n      \"evidence\": \"In vitro ATPase, homologous pairing, and strand exchange assays with purified human RAD51\",\n      \"pmids\": [\"9012806\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No accessory factors tested\", \"Basis for lower activity versus RecA undefined\", \"No structural data on human RAD51 filaments\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Demonstrating that ATP binding induces a conformational change in RAD51 that stabilizes its DNA-binding-competent state resolved how nucleotide cofactors regulate filament formation, and identifying BRCA2 as an in vivo RAD51 partner connected recombination to breast cancer susceptibility.\",\n      \"evidence\": \"CD spectroscopy and equilibrium dialysis on purified RAD51; co-immunoprecipitation of BRCA2-RAD51 complexes in human cells\",\n      \"pmids\": [\"9718317\", \"9811893\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"BRCA2-RAD51 interaction mechanism unresolved\", \"Structural basis of ATP-induced conformational change unknown\", \"No reconstitution of BRCA2 mediator activity\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Discovery that Rad54 physically interacts with Rad51 and stimulates homologous pairing established the first defined accessory factor that enhances RAD51 strand exchange.\",\n      \"evidence\": \"Co-immunoprecipitation and in vitro DNA pairing assays with purified yeast Rad54 and Rad51\",\n      \"pmids\": [\"9590697\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of Rad54 stimulation unclear\", \"Human system not yet tested\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Visualization of RAD51 redistribution to UV-damaged chromatin in S-phase cells demonstrated that RAD51 is actively recruited to damage sites in vivo, preferentially associating with postreplicative chromatin.\",\n      \"evidence\": \"UV microirradiation with immunofluorescence and halogenated thymidine dual-labeling in human fibroblasts\",\n      \"pmids\": [\"10908572\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Recruitment mechanism and upstream signals undefined\", \"Role of mediators in recruitment not addressed\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Dissection of RPA's primary role as a postsynaptic stabilizer of strand exchange intermediates, and demonstration that Rad54 promotes DNA supercoiling through RAD51-stimulated ATPase activity, defined two cooperative mechanisms that drive the strand exchange reaction forward.\",\n      \"evidence\": \"In vitro strand exchange with deproteinization controls (RPA role); ATPase, supercoiling, and pairing assays with purified human RAD51 and RAD54\",\n      \"pmids\": [\"12169690\", \"12205100\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full reconstitution of pre- through post-synaptic steps not achieved\", \"In vivo validation of postsynaptic RPA role lacking\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Demonstration that yeast Srs2 helicase dismantles Rad51 presynaptic filaments established the first anti-recombinase mechanism, revealing that filament stability is actively regulated.\",\n      \"evidence\": \"In vitro Rad51 filament disruption and recombination inhibition assays with purified Srs2\",\n      \"pmids\": [\"12748644\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Human anti-recombinase counterpart not identified\", \"In vivo dynamics of Srs2-Rad51 interplay unresolved\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Structural analysis of BRC repeat–RAD51 filament interactions revealed that individual BRC repeats contact distinct RAD51 domains, explaining how BRCA2 can both stabilize and (at excess) disrupt filaments, while MDC1 was identified as a chromatin retention factor for RAD51.\",\n      \"evidence\": \"Electron microscopy of BRC peptide–RAD51 filament complexes; RNAi, co-IP, and chromatin fractionation for MDC1\",\n      \"pmids\": [\"15937124\", \"16186822\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full-length BRCA2 structure on filaments not determined\", \"Interplay between MDC1 retention and BRCA2 loading unknown\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identification of Tyr232 in the L1 loop as critical for DNA binding provided the first residue-level map of the RAD51-DNA interface, linking loop structure to filament function.\",\n      \"evidence\": \"Site-directed mutagenesis with gel retardation, ATPase, and fluorescence assays on purified human RAD51\",\n      \"pmids\": [\"16780572\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No high-resolution structure of human RAD51-DNA complex yet\", \"L2 loop residue contributions not fully defined\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Showing that RAD51 ATPase activity and Rad54 ATPase cooperate for RAD51 turnover from dsDNA product resolved how the recombinase is recycled after strand exchange, preventing toxic accumulation on product DNA.\",\n      \"evidence\": \"ATPase kinetics, EM, and Walker box mutagenesis (K191R) with purified proteins\",\n      \"pmids\": [\"17567608\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo validation of turnover mechanism lacking\", \"Whether additional factors assist turnover unknown\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"RAD51 was shown to stimulate Rad54-mediated Holliday junction branch migration and to channel DSB repair toward strand invasion by inhibiting Rad52-mediated annealing, establishing RAD51 as a pathway selector beyond its catalytic role.\",\n      \"evidence\": \"In vitro branch migration and ssDNA annealing assays with purified yeast and human proteins\",\n      \"pmids\": [\"18617519\", \"18337252\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo pathway channeling quantification lacking\", \"Human Rad52 functional contribution unclear\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Reconstitution with purified full-length BRCA2 demonstrated its mediator function: BRCA2 targets RAD51 to ssDNA over dsDNA, displaces RPA, and stabilizes filaments by blocking ATP hydrolysis, definitively establishing BRCA2 as the primary human recombination mediator.\",\n      \"evidence\": \"In vitro DNA binding, strand exchange, and filament stability assays with purified full-length human BRCA2 and RAD51\",\n      \"pmids\": [\"20729832\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of full-length BRCA2 on filaments unresolved\", \"Contribution of individual BRC repeats in full-length context unclear\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identification of Mec1-dependent phosphorylation at Ser192 as required for RAD51 ATPase and DNA binding linked checkpoint signaling directly to recombinase activation.\",\n      \"evidence\": \"In vitro kinase assay, ATPase, DNA binding with phosphosite mutants, and in vivo HR assay in yeast\",\n      \"pmids\": [\"21738226\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Human equivalent phosphosite not characterized\", \"Structural impact of phosphorylation unknown\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"HOP2-MND1 was shown to act as a molecular trigger that reprograms RAD51 DNA-binding specificity and nucleotide interaction, enabling strand exchange even without divalent cations, revealing an allosteric activation mechanism.\",\n      \"evidence\": \"In vitro strand exchange, nucleotide binding, and ATPase assays with purified proteins\",\n      \"pmids\": [\"24943459\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of HOP2-MND1-induced conformational change unresolved\", \"Meiotic versus mitotic specificity of this regulation unclear\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Demonstration that RAD51 paralog complex RFS-1/RIP-1 remodels RAD51 filaments to a stabilized open conformation via its Walker box ATPase activity established a filament-remodeling mechanism distinct from BRCA2-mediated nucleation.\",\n      \"evidence\": \"Single-molecule imaging, EM, ATPase mutagenesis, and strand exchange assays with purified C. elegans proteins\",\n      \"pmids\": [\"26186187\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether human RAD51 paralogs use the same remodeling mechanism untested in vitro\", \"Structural basis of open conformation unknown\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"TOPBP1 was found to promote PLK1-mediated phosphorylation of RAD51 at Ser14, required for chromatin recruitment, and MMS22L-TONSL was shown to limit dsDNA binding and stimulate ssDNA filament formation, expanding the network of RAD51 regulators at replication forks.\",\n      \"evidence\": \"Kinase assay, co-IP, chromatin fractionation for TOPBP1-PLK1-RAD51; in vitro reconstitution and DNA fiber assay for MMS22L-TONSL\",\n      \"pmids\": [\"26811421\", \"27797818\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How Ser14 phosphorylation mechanistically promotes chromatin loading unknown\", \"Coordination between BRCA2 and MMS22L-TONSL at forks unresolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Single-molecule imaging quantified Srs2 as a processive translocase stripping ~50 RAD51 monomers per second, recruited to RPA clusters within filaments, revealing the kinetic basis of anti-recombination.\",\n      \"evidence\": \"Single-molecule ssDNA curtain assays with purified yeast proteins\",\n      \"pmids\": [\"29241544\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Human functional equivalent of Srs2 processivity not measured\", \"In vivo rates not confirmed\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"RADX was identified as a human anti-recombinase that competes with RAD51 for ssDNA at stalled forks, and epistasis analysis showed that RADX depletion rescues fork protection in BRCA1/2 and Fanconi anemia mutants, establishing RAD51 filament density as the determinant of fork fate.\",\n      \"evidence\": \"siRNA epistasis across multiple HR mutants, DNA fiber assay, ssDNA competition binding\",\n      \"pmids\": [\"30021152\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct structural basis of RADX-RAD51 competition unknown\", \"How cells calibrate RADX/RAD51 balance unclear\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"RADX was shown to condense ssDNA into higher-order assemblies that physically block RAD51 loading, even on RPA-coated substrates, providing a mechanistic explanation for how RADX antagonizes RAD51 beyond simple competition.\",\n      \"evidence\": \"Single-molecule ssDNA curtain imaging with purified RADX, RPA, and RAD51\",\n      \"pmids\": [\"32621611\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo condensation not demonstrated\", \"Regulation of RADX condensation activity unknown\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Biochemical reconstitution showed RADX directly binds ATP-bound RAD51 to stimulate its ATPase and destabilize filaments, while cryo-EM structures identified Loop2 residues V273/D274 as determinants of mismatch intolerance during strand exchange, and RAD51 was found to protect abasic sites from MRE11-RAD50 cleavage.\",\n      \"evidence\": \"In vitro strand exchange/D-loop/ATPase assays plus single-molecule imaging for RADX; cryo-EM with mutagenesis and smFRET for mismatch discrimination; cryo-EM plus Xenopus extract reconstitution for abasic site protection\",\n      \"pmids\": [\"33453169\", \"34871438\", \"39178838\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether abasic site protection is separable from strand exchange in vivo unclear\", \"Full structural view of RADX-RAD51 complex lacking\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"TOPORS-mediated SUMOylation of RAD51 at K57/K70, triggered by ATM phosphorylation, was shown to be required for BRCA2 interaction and chromatin loading, and PRDX1-dependent reduction of Cys319 was found essential for filament formation, adding two post-translational regulatory layers.\",\n      \"evidence\": \"SUMO assay, mutagenesis, chromatin fractionation, HR reporter for TOPORS-RAD51; sulfenylation probe, PRDX1 KO cells, MD simulation, HR reporter for Cys319 redox regulation\",\n      \"pmids\": [\"35061896\", \"36058112\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How SUMOylation structurally promotes BRCA2 binding unknown\", \"In vivo redox dynamics of Cys319 during repair not tracked\", \"Interplay between phosphorylation and SUMOylation uncharacterized\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Multiple breakthroughs resolved how BRCA2 chaperones pre-assembled RAD51 onto RPA-ssDNA via kinetic nucleation, how the BRCA2 TR2 motif braces filament protomers at an acidic-patch hub, how RAD51 bypasses CMG helicase during fork reversal via strand exchange, and how filaments undergo dynamic compaction-extension cycles in vivo for homology search.\",\n      \"evidence\": \"Single-molecule kinetics with full-length BRCA2; cryo-EM of TR2-RAD51 filament; auxin degron and DNA fiber assay for CMG bypass; in vivo single-molecule tracking of functional tagged Rad51 in yeast\",\n      \"pmids\": [\"36976771\", \"37919288\", \"37104614\", \"37605042\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Complete structural model of BRCA2 on the RAD51-ssDNA filament still lacking\", \"How filament dynamics are coordinated with chromatin environment in mammalian cells unknown\", \"Mechanism by which DNA translocases complete fork reversal after RAD51-mediated CMG bypass unresolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Conditional RAD51 knockout in mouse germ cells established that RAD51 is essential for spermatogonial survival and meiotic crossover formation, extending its role beyond somatic DSB repair.\",\n      \"evidence\": \"Conditional knockout mouse models (Vasa-Cre and UBC-CreERT2) with histology and crossover analysis\",\n      \"pmids\": [\"35292640\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contributions of RAD51 versus DMC1 at specific meiotic DSB ends not fully delineated\", \"Mechanistic basis of spermatogonial loss beyond DSB accumulation unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A complete structural model of full-length BRCA2 bound to a RAD51-ssDNA filament, the in vivo coordination between multiple positive and negative regulators (BRCA2, RADX, Srs2/FIGNL1, MMS22L-TONSL) at individual replication forks, and the structural basis of post-translational modification crosstalk (phosphorylation, SUMOylation, redox) on filament dynamics remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No atomic structure of full-length BRCA2-RAD51-ssDNA complex\", \"In vivo quantitative balance of pro- and anti-recombinase activities at single forks not measured\", \"Structural basis for how SUMOylation at K57/70 promotes BRCA2 binding unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [3, 15, 17, 20]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [3, 19, 20, 22]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [3, 4, 14, 21]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [8, 25, 27, 36]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [27, 29, 35]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [0, 3, 7, 11, 22, 25]},\n      {\"term_id\": \"R-HSA-69306\", \"supporting_discovery_ids\": [9, 11, 13]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [37]},\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [37]}\n    ],\n    \"complexes\": [\n      \"RAD51 nucleoprotein filament\",\n      \"BRCA2-RAD51 complex\"\n    ],\n    \"partners\": [\n      \"BRCA2\",\n      \"RAD54L\",\n      \"RADX\",\n      \"MDC1\",\n      \"TOPBP1\",\n      \"MMS22L\",\n      \"TOPORS\",\n      \"PRDX1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"mechanistic_narrative\": \"RAD51 is a RecA-family recombinase that assembles ATP-dependent helical nucleoprotein filaments on single-stranded DNA to catalyze homology search and strand exchange, forming the central enzymatic activity of homologous recombination repair of DNA double-strand breaks, replication fork reversal, and nascent DNA protection [PMID:7988572, PMID:8929543, PMID:25733714, PMID:37104614]. Filament nucleation on RPA-coated ssDNA is rate-limited and overcome by BRCA2, which chaperones preassembled RAD51 onto ssDNA, blocks RAD51 ATP hydrolysis to stabilize the active filament, and targets RAD51 to ssDNA over dsDNA [PMID:20729832, PMID:36976771, PMID:12442171]; filament dynamics are further tuned by stimulatory cofactors (Rad54, HOP2-MND1, RAD51 paralogs, MMS22L-TONSL) and antagonists (Srs2, RADX, BLM) that respectively stabilize or dismantle filaments [PMID:12205100, PMID:24943459, PMID:12748644, PMID:33453169, PMID:27797818]. Multiple post-translational modifications regulate RAD51 chromatin loading and activity, including Chk1-mediated T309 phosphorylation, TOPBP1/PLK1-mediated S14 phosphorylation, TOPORS-dependent SUMOylation at K57/K70, CDK-dependent phosphorylation of BRCA2-S3291 that gates the BRCA2–RAD51 interaction across the cell cycle, and PRDX1-maintained reduction of the redox-sensitive C319 residue [PMID:15665856, PMID:26811421, PMID:35061896, PMID:15800615, PMID:36058112].\",\n  \"teleology\": [\n    {\n      \"year\": 1994,\n      \"claim\": \"Identifying RAD51 as a functional human RecA homolog resolved whether eukaryotes possess a dedicated strand-exchange recombinase: purified human RAD51 bound DNA, hydrolyzed ATP, unwound duplexes, and formed helical nucleoprotein filaments.\",\n      \"evidence\": \"Protein purification, ATPase assay, topological unwinding, electron microscopy of filaments\",\n      \"pmids\": [\"7988572\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No strand exchange demonstrated yet\", \"Cofactor requirements unknown\", \"No in vivo functional proof\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Demonstrating that human RAD51 catalyzes ATP-dependent homologous pairing and strand exchange in vitro established the core enzymatic activity of the protein, while revealing that its intrinsic rate is much lower than RecA and requires accessory factors for extensive heteroduplex formation.\",\n      \"evidence\": \"In vitro strand exchange assay with purified hRAD51 and RPA\",\n      \"pmids\": [\"8929543\", \"9012806\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of required accessory factors unknown\", \"Relationship between ATP hydrolysis and strand exchange kinetics unclear\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Discovery of direct BRCA2–RAD51 and BRCA1–RAD51 interactions placed the hereditary breast cancer tumor suppressors in the homologous recombination pathway, with BRCA2's BRC repeats providing the molecular interface to RAD51.\",\n      \"evidence\": \"Co-immunoprecipitation, yeast two-hybrid mapping of BRC motifs to RAD51 residues 98–339, BRCA2-null mouse embryo phenotyping\",\n      \"pmids\": [\"9405383\", \"9126738\", \"9008167\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How BRCA2 mechanistically promotes RAD51 activity unknown\", \"Full-length BRCA2 not yet purified\", \"BRCA1's direct role vs. indirect scaffolding unclear\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"ATP/Mg²⁺-induced conformational switching of RAD51 and its accumulation at UV-damaged chromatin during S phase established that RAD51 adopts a catalytically competent conformation upon nucleotide binding and functions in the context of DNA replication.\",\n      \"evidence\": \"Circular dichroism spectroscopy, equilibrium dialysis, UV microirradiation with BrdU fractionation\",\n      \"pmids\": [\"9718317\", \"10908572\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of conformational change unknown\", \"Whether RAD51 foci represent active filaments unclear\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Placing γ-H2AX upstream of RAD51 focus formation and identifying RAD51 paralog complexes (RAD51B/C/D, XRCC2/3) defined the signaling hierarchy: PI-3 kinase–dependent H2AX phosphorylation is required for RAD51 recruitment, and paralog sub-complexes act as mediators.\",\n      \"evidence\": \"Wortmannin inhibition of γ-H2AX abolishes RAD51 foci; yeast two/three-hybrid and baculovirus co-expression of paralog complexes\",\n      \"pmids\": [\"10959836\", \"10749867\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct mechanism by which paralogs load RAD51 unknown\", \"Paralog complex stoichiometry undefined\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Crystal structure of the BRC repeat–RAD51 complex revealed that BRC mimics the RAD51 protomer–protomer interface, explaining how BRCA2 controls filament assembly; concurrently, RPA's postsynaptic role in stabilizing strand exchange products and Rad54's ATP-dependent cooperation with RAD51 were mechanistically dissected.\",\n      \"evidence\": \"X-ray crystallography of BRC–RAD51; in vitro strand exchange with RPA deproteinization controls; Rad54 supercoiling/branch migration assays\",\n      \"pmids\": [\"12442171\", \"12169690\", \"12205100\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full-length BRCA2 not structurally resolved\", \"How individual BRC repeats differ in function unclear\", \"Rad54's in vivo contribution to branch migration not tested\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Discovery that Srs2 helicase dismantles RAD51 presynaptic filaments established the first anti-recombination mechanism targeting RAD51 directly, providing a framework for understanding how inappropriate recombination is prevented.\",\n      \"evidence\": \"In vitro reconstitution with purified Srs2 and Rad51; filament disruption assay\",\n      \"pmids\": [\"12748644\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Human Srs2 functional ortholog not identified\", \"Whether Rad52 can counteract Srs2 unknown\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Multiple regulatory inputs were identified: CDK phosphorylation of BRCA2-S3291 gates RAD51 binding across the cell cycle, Chk1 phosphorylation of RAD51-T309 is required for damage-induced focus formation, and MDC1 retains RAD51 on chromatin—collectively establishing that RAD51 is regulated by checkpoint kinases, CDK, and chromatin adaptor proteins.\",\n      \"evidence\": \"Phospho-specific antibodies, cell-cycle fractionation, in vitro kinase assays, siRNA, RAD51-T309A mutagenesis, MDC1 FHA-domain mapping\",\n      \"pmids\": [\"15800615\", \"15665856\", \"16186822\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Interplay between T309 and S14 phosphorylation not explored\", \"Whether CDK-BRCA2-S3291 is the sole cell-cycle switch unclear\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Purification of full-length BRCA2 finally demonstrated its direct biochemical mechanism: BRCA2 nucleates RAD51 filaments by targeting RAD51 to ssDNA, displacing RPA, and blocking RAD51's ATP hydrolysis to stabilize the active filament; concurrently, DNA fiber analysis separated RAD51's fork restart function from its HR repair function.\",\n      \"evidence\": \"Full-length BRCA2 purification with in vitro strand exchange, filament stability, and RPA displacement assays; DNA fiber assay in XRCC3-mutant and siRAD51 cells\",\n      \"pmids\": [\"20729832\", \"20188668\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether BRCA2 forms a stoichiometric or catalytic complex with RAD51 unclear\", \"Structural basis of BRCA2 blocking ATP hydrolysis unknown\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"RAD51-mediated replication fork reversal was established as a global cellular response to genotoxic stress, and RAD51 paralog complexes were shown to remodel presynaptic filaments into an 'open' conformation that facilitates strand exchange, defining the structural output of paralog action.\",\n      \"evidence\": \"EM of replication fork architecture in human cells after RAD51 depletion; single-molecule FRET and EM of RFS-1/RIP-1 filament remodeling in C. elegans\",\n      \"pmids\": [\"25733714\", \"26186187\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether human RAD51B-C or RAD51C-XRCC3 remodel filaments analogously unknown\", \"Specific RAD51 domains required for fork reversal not mapped\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"RADX was identified as a ssDNA-binding antagonist of RAD51 at stalled forks, and Rad52 was shown to protect Rad51 filaments from Srs2 disruption—together establishing that the balance between filament stabilizers and destabilizers determines fork protection versus degradation.\",\n      \"evidence\": \"DNA fiber assays across BRCA1/2- and FA-deficient backgrounds with RADX silencing; separation-of-function Rad52 mutants with Srs2 disruption assay in vitro and in vivo\",\n      \"pmids\": [\"30021152\", \"29985128\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether RADX acts identically at DSB-associated ssDNA unclear\", \"Human RAD52's filament-protective role not directly tested\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Mechanistic dissection of RADX revealed it directly binds ATP-bound RAD51 and stimulates its ATPase to destabilize filaments; MMS22L-TONSL was shown to limit RAD51 dsDNA binding to promote productive ssDNA filament formation; and conditional RAD51 knockout in mice demonstrated essential roles in spermatogonial maintenance and meiotic crossover formation.\",\n      \"evidence\": \"In vitro ATPase/strand exchange with RADX and RAD51; iPOND and reconstitution with MMS22L-TONSL; Vasa-Cre and UBC-CreERT2 conditional knockouts in mouse germ cells\",\n      \"pmids\": [\"33453169\", \"27797818\", \"35292640\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"RADX structural basis of RAD51 interaction unknown\", \"MMS22L-TONSL mechanism of ssDNA selectivity not structurally explained\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Two new regulatory layers were discovered: TOPORS SUMOylates RAD51 at K57/K70 downstream of ATM to promote chromatin loading and BRCA2 interaction, and PRDX1 maintains RAD51-C319 in a reduced state required for DNA binding, establishing redox and SUMO control of filament competence.\",\n      \"evidence\": \"SUMO modification assays with TOPORS, SUMOylation-deficient RAD51-K57R/K70R mutants, HR reporter; sulfenylation probes, PRDX1-deficient cells, RAD51-C319 mutagenesis, molecular dynamics\",\n      \"pmids\": [\"35061896\", \"36058112\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Interplay between SUMOylation and phosphorylation of RAD51 not characterized\", \"Whether C319 oxidation occurs under physiological oxidative stress in vivo not established\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Cryo-EM structures resolved how BRCA2's TR2 motif braces adjacent RAD51 protomers across the filament interface and how RAD51 Loop2 residues V273/D274 enforce mismatch intolerance during strand exchange; in vivo imaging revealed nucleus-spanning RAD51 filaments that undergo Rad54/Srs2-modulated compaction-extension cycles to conduct homology search; and RAD51 strand exchange activity was shown to bypass the CMG helicase at stalled forks to initiate fork reversal.\",\n      \"evidence\": \"Cryo-EM of BRCA2-TR2–RAD51 and RAD51/DMC1–DNA complexes; live-cell single-molecule imaging of tagged Rad51 filaments; auxin-inducible CMG depletion with EM and fiber assays\",\n      \"pmids\": [\"37919288\", \"34871438\", \"37605042\", \"37104614\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full cryo-EM structure of BRCA2-loaded RAD51 filament not yet available\", \"How filament compaction-extension is coordinated with chromatin architecture unknown\", \"Structural basis of CMG bypass not resolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"RAD51 was found to specifically recognize and protect abasic sites in ssDNA from MRE11-RAD50 nucleolytic cleavage, expanding its fork-protection function beyond simple ssDNA coating to lesion-specific shielding of damaged replication intermediates.\",\n      \"evidence\": \"Cryo-EM of RAD51 on abasic DNA, Xenopus egg extract fork protection assays, human cell experiments with APE1/MRE11 cleavage readouts\",\n      \"pmids\": [\"39178838\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether other DNA lesion types are similarly recognized by RAD51 unknown\", \"In vivo frequency and genomic distribution of abasic-site protection events not determined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A comprehensive structural model of full-length BRCA2 bound to a complete RAD51 nucleoprotein filament during active strand exchange remains unresolved, as does the precise mechanism by which RAD51 filament dynamics are spatially coordinated with chromatin topology and replication fork architecture in mammalian cells.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No full-length BRCA2–RAD51 filament structure available\", \"Structural basis of RAD51's CMG bypass mechanism unresolved\", \"How multiple PTMs are integrated in space and time during a single repair event is unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [0, 1, 2, 6, 27]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [0, 1, 6, 26]},\n      {\"term_id\": \"GO:0140097\", \"supporting_discovery_ids\": [1, 2, 34, 53]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [3, 8, 10, 12, 56]},\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [8, 25, 37, 55]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [1, 5, 14, 20, 31, 32, 49]},\n      {\"term_id\": \"R-HSA-69306\", \"supporting_discovery_ids\": [32, 35, 41, 53, 57]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [22, 37]},\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [43, 48]}\n    ],\n    \"complexes\": [\n      \"RAD51 nucleoprotein filament\",\n      \"BRCA1-BRCA2-RAD51 complex\"\n    ],\n    \"partners\": [\n      \"BRCA2\",\n      \"BRCA1\",\n      \"RAD54L\",\n      \"RAD52\",\n      \"RADX\",\n      \"MMS22L\",\n      \"TOPORS\",\n      \"HELQ\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}