{"gene":"HELQ","run_date":"2026-06-10T01:55:22","timeline":{"discoveries":[{"year":2007,"finding":"Crystal structure of archaeal Hel308 (Sulfolobus solfataricus) reveals a five-domain architecture with a central pore lined with essential DNA-binding residues; domain V acts as an autoinhibitory 'molecular brake' that clamps single-stranded DNA extruded through the central pore, limiting helicase processivity. Hel308 can displace streptavidin from biotinylated DNA, and this protein-displacement activity is only partially inhibited by RPA or Alba1 pre-bound to DNA, while RadA pre-binding has no effect.","method":"X-ray crystallography (high-resolution crystal structure), in vitro helicase/protein-displacement assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with functional validation by in vitro assays; multiple orthogonal methods in one study","pmids":["18056710"],"is_preprint":false},{"year":2007,"finding":"Mutagenesis of three arginine residues in domain V of archaeal Hel308 demonstrates that domain V couples DNA binding to ATP hydrolysis and positions single-stranded DNA relative to the helicase ratchet domain IV for efficient fork unwinding.","method":"Site-directed mutagenesis, in vitro ATPase assay, DNA-binding and unwinding assays","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — active-site mutagenesis combined with multiple in vitro biochemical assays in a single focused study","pmids":["17991488"],"is_preprint":false},{"year":2005,"finding":"Archaeal Hel308 targets stalled replication forks in vivo (introduction into E. coli dnaE strains causes synthetic lethality, phenocopying RecQ) and in vitro specifically displaces lagging strands from fork structures; it also targets the invading strand of D-loops.","method":"In vivo genetic complementation (E. coli dnaE conditional lethality), in vitro helicase assays on replication fork and D-loop substrates","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — in vitro biochemical assay combined with in vivo genetic epistasis; multiple orthogonal approaches","pmids":["15994460"],"is_preprint":false},{"year":2011,"finding":"Human HEL308 (HELQ) localizes to damaged replication forks after camptothecin treatment, co-localizing with RAD51 and FANCD2. Purified HEL308 requires a 3′ single-stranded overhang to load onto DNA, preferentially unwinds the parental strands of a model stalled fork with a nascent lagging strand, and its unwinding activity is specifically stimulated by human RPA.","method":"GFP-tag live-cell imaging and co-localization, in vitro helicase assays with purified proteins, RPA stimulation assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — direct localization experiment with functional consequence, combined with in vitro biochemical reconstitution; multiple orthogonal methods","pmids":["21398521"],"is_preprint":false},{"year":2010,"finding":"Archaeal Hel308 physically interacts with RPA (but not SSB); interaction requires a conserved amino acid motif at the Hel308 C-terminus. RPA modestly stimulates Hel308 helicase activity (1.5–2 fold), supporting a model in which RPA loads Hel308 onto ssDNA at blocked replication forks rather than directly stimulating its unwinding mechanism.","method":"Co-immunoprecipitation / pulldown assays, deletion/mutation mapping, in vitro helicase stimulation assays","journal":"DNA repair","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — physical interaction mapped by pulldown with motif mapping, plus functional helicase stimulation assay; single lab","pmids":["21195035"],"is_preprint":false},{"year":2013,"finding":"HELQ directly interacts with the RAD51 paralogue complex BCDX2 and functions in parallel to the Fanconi anaemia pathway to promote homologous recombination at damaged replication forks. Helicase-deficient Helq mice show subfertility, germ cell attrition, ICL sensitivity and tumour predisposition.","method":"Co-immunoprecipitation (direct interaction with BCDX2), mouse knockout phenotyping, epistasis with FA pathway","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP establishing direct interaction, in vivo mouse model with defined phenotypic readouts, and genetic epistasis placing HELQ parallel to FA pathway; multiple orthogonal approaches across labs","pmids":["24005329"],"is_preprint":false},{"year":2013,"finding":"Human HELQ is associated with RAD51 paralogs RAD51B/C/D and XRCC2, and with the DNA damage-responsive kinase ATR, as revealed by proteomic analysis. HELQ knockout in human cells enhances sensitivity to mitomycin C and chromosome radial formation, and reduces CHK1 phosphorylation after MMC treatment, indicating HELQ participates in ATR-CHK1 signaling in response to ICL.","method":"Proteomic analysis (co-IP/MS), HELQ knockout in human cells, MMC sensitivity assay, immunoblot for CHK1 phosphorylation","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — proteomic interactome plus functional KO phenotype with signaling readout; two independent Nature-family papers in same year converge on RAD51 paralog interaction","pmids":["24005565"],"is_preprint":false},{"year":2013,"finding":"Helq acts in parallel (non-epistatic) to Fancc in suppressing spontaneous chromosome instability (micronuclei, 53BP1 nuclear bodies) and ICL sensitivity in mice; Helq-deficient cells have intact FANCD2 mono-ubiquitination and focus formation, placing HELQ outside the canonical FA core complex pathway.","method":"Mouse double mutant (Helqgt/gt; Fancc−/−) epistasis analysis, FANCD2 ubiquitination assay, cytogenetic analysis","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean genetic epistasis with double-mutant mice and multiple cellular phenotype readouts; independent of the two 2013 Nature/Nature Comm papers","pmids":["24005041"],"is_preprint":false},{"year":2017,"finding":"The winged helix domain (WHD) of Hel308 promotes DNA binding and unwinding: mutations in a solvent-exposed α-helix of the WHD reduce DNA binding and unwinding. Isolated WHD binds duplex DNA but not ssDNA, and disrupting the interface between the WHD and the RecA-like domain abolishes ATPase and helicase activities. The isolated WHD of human HelQ also binds duplex DNA.","method":"Site-directed mutagenesis, in vitro DNA-binding assays, ATPase assay, helicase assay with isolated domain constructs","journal":"DNA repair","confidence":"High","confidence_rationale":"Tier 1 / Moderate — active-site/domain mutagenesis combined with multiple in vitro biochemical assays; isolated domain analysis confirms functional role","pmids":["28738244"],"is_preprint":false},{"year":2019,"finding":"Single-molecule nanopore tweezers (SPRNT) reveal that DNA bases at two specific sites within Hel308 control the kinetics of an ATP-independent step in the ATP hydrolysis cycle, demonstrating sequence-specific translocation kinetics during ssDNA translocation.","method":"Single-molecule SPRNT (picometer-resolution nanopore tweezers)","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — novel single-molecule method with high resolution; single lab, single study on archaeal ortholog","pmids":["30649515"],"is_preprint":false},{"year":2021,"finding":"HELQ possesses both helicase and DNA strand annealing activities that are differentially regulated: RAD51 forms a complex with HELQ and strongly stimulates its translocation/unwinding activity, whereas RPA inhibits DNA unwinding but strongly stimulates DNA strand annealing. HELQ can capture RPA-bound ssDNA strands and displace RPA to facilitate annealing of complementary sequences. HELQ deficiency impairs single-strand annealing (SSA) and microhomology-mediated end-joining (MMEJ) pathways and biases towards long-tract gene conversion during homologous recombination.","method":"Biochemical reconstitution, single-molecule imaging, HELQ-deficient cell lines with specific pathway assays (SSA, MMEJ, gene conversion tract analysis)","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — biochemical reconstitution combined with single-molecule imaging and cell-based pathway-specific assays; multiple orthogonal methods in a single rigorous study","pmids":["34937945"],"is_preprint":false},{"year":2021,"finding":"The N-terminal non-catalytic region of human HelQ contains a PWI-like domain that mediates interaction with RPA to orchestrate loading of HelQ helicase domains onto ssDNA. Once loaded, HelQ translocates along ssDNA as a dimer, activated by ATP-Mg2+ binding at the catalytic site. Specific HelQ-ssDNA interactions critical for the translocation mechanism were identified.","method":"Domain characterization with deletion constructs, RPA interaction assays (pulldown), in vitro helicase/translocation assays, mutagenesis of ssDNA contact residues","journal":"NAR cancer","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — multiple biochemical methods including domain mapping, pulldown interaction, and translocation assays; identifies new functional domain with mechanistic follow-up","pmids":["34316696"],"is_preprint":false},{"year":2022,"finding":"In Drosophila, HELQ, BLM, and FANCM helicases play distinct roles during synthesis-dependent strand annealing (SDSA): double mutants (blm helq and helq fancm) show more severe SDSA defects than single mutants, and HELQ and FANCM act early to promote formation of recombination intermediates that are then processed by BLM to prevent deletion-prone repair.","method":"Drosophila genetic double-strand gap repair assay, double mutant epistasis analysis","journal":"Genes","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with defined HR pathway readout in Drosophila; double mutant analysis; consistent with mammalian data","pmids":["35328029"],"is_preprint":false},{"year":2023,"finding":"Human HelQ halts DNA synthesis by DNA polymerase delta (Pol δ) and Pol δ-PCNA-RPA holoenzyme; this inhibition is independent of HelQ DNA binding and maps to a 70-amino-acid intrinsically disordered region of HelQ. POLD3 subunit of Pol δ physically interacts with HelQ via this intrinsically disordered region and strongly stimulates HelQ DNA strand annealing activity. HelQ cannot inhibit the isolated POLD1 catalytic subunit alone.","method":"In vitro DNA synthesis inhibition assays, novel HelQ mutant proteins, pulldown/Co-IP (POLD3-HelQ interaction), DNA strand annealing assays","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with domain-mapped mutants; identifies physical interaction and functional consequence; multiple orthogonal biochemical approaches","pmids":["36718939"],"is_preprint":false},{"year":2023,"finding":"HELQ helicase activity is required for EXO1-mediated DNA end resection at double-strand breaks (DSBs), while the ssDNA-binding capacity of HELQ is required for its recruitment to stalled replication forks, where it facilitates fork protection and prevents chromosome aberrations. HELQ synergizes with CtIP (but not BRCA1 or BRCA2) to protect stalled forks.","method":"HELQ knockout/mutant cells, resection assays (RPA/ssDNA accumulation), replication fork protection assays (DNA fiber), epistasis with CtIP/BRCA1/BRCA2, chromosome aberration analysis","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell-based functional assays with separation-of-function mutants and genetic epistasis; single lab","pmids":["37897354"],"is_preprint":false},{"year":2023,"finding":"A conserved motif IVa (F/YHHAGL) in the RecA2 domain of archaeal Hel308/HELQ acts as a catalytic switch modulating both DNA unwinding and strand annealing: a single amino acid substitution in motif IVa produces hyper-active helicase and annealase activities in vitro and causes a 160,000-fold increase in gene conversion (non-crossover) recombination in archaeal cells, while crossover recombination is unaffected.","method":"Site-directed mutagenesis, in vitro helicase and strand-annealing assays, all-atom molecular dynamics simulations, in vivo recombination assay in archaea","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1 / Strong — active-site mutagenesis, in vitro biochemical reconstitution, MD simulations, and in vivo genetic assay provide convergent multi-method evidence","pmids":["37409572"],"is_preprint":false},{"year":2023,"finding":"FANCD2-driven mitotic DNA synthesis (MiDAS) in untransformed human cells requires HELQ, which functions at an early step of this pathway; FANCD2 mono-ubiquitination by FA proteins is a prerequisite step upstream.","method":"HELQ-deficient cell analysis, MiDAS assay (EdU incorporation on metaphase chromosomes), genetic epistasis with FA pathway components","journal":"Journal of molecular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — cell-based MiDAS assay with HELQ-deficient cells and FA epistasis; single lab; step placement is inferred as 'early' without full mechanistic resolution","pmids":["37777152"],"is_preprint":false},{"year":2024,"finding":"In C. elegans, HELQ (hel-308) participates in end-joining during ICL repair, contributing to deletion formation at psoralen ICL sites; this is distinct from translesion synthesis-driven SNV formation mediated by POLH/REV1/3.","method":"C. elegans mutant analysis, whole-genome sequencing of repair products, epistasis with FA pathway (FANCD2, FANCI), TRAIP and FAN1 genetic analysis","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with mutational signature readout; multi-gene analysis in C. elegans model; convergent with prior ICL repair role","pmids":["40082407"],"is_preprint":false},{"year":2024,"finding":"HELQ specifically suppresses cisplatin sensitivity caused by PRIMPOL-generated ssDNA gaps, with this suppression associated with reduced ssDNA accumulation. RAD52 acts as a mediator downstream; RAD52 promotes ssDNA gap accumulation through a BRCA-mediated mechanism, defining a HELQ–RAD52–BRCA axis in ssDNA gap processing.","method":"CRISPR genome-wide knockout screens, PRIMPOL-overexpression model, ssDNA accumulation assays, genetic epistasis (HELQ/RAD52/BRCA)","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genome-wide CRISPR screen followed by targeted epistasis validation; multiple methods but pathway placement partially inferential","pmids":["39530221"],"is_preprint":false},{"year":2025,"finding":"HELQ is recruited by RPA at R-loops and resolves R-loops in a manner dependent on its ATPase/helicase catalytic activity. HELQ functionally interacts with the nuclear 5'–3' exoribonuclease XRN2, coordinating R-loop unwinding (by HELQ) with RNA digestion (by XRN2).","method":"Cell-based R-loop assays (S9.6 immunofluorescence), in vitro R-loop resolution assay with purified proteins, co-IP (HELQ–XRN2 interaction), catalytic-dead HELQ mutant","journal":"Open biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell-based and in vitro assays combined with Co-IP; catalytic-dead mutant validates mechanism; single lab","pmids":["39965657"],"is_preprint":false},{"year":2025,"finding":"HELQ interacts with the H3K9me3 demethylase KDM4B in primordial germ cells (PGCs); HELQ deficiency increases total and chromatin-bound KDM4B levels, reducing H3K9me3 at LINE-1 retrotransposon regions, which triggers LINE-1 expression and DNA damage accumulation in PGCs. Retrotransposition inhibition rescues the developmental defects of HELQ-deficient PGCs.","method":"Mouse Helq knockout, Co-IP (HELQ–KDM4B interaction), ChIP (H3K9me3 at LINE-1), retrotransposition inhibitor rescue experiment, PGC proliferation assays","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP identifies new interaction, ChIP links it to chromatin mechanism, and pharmacological rescue validates pathway; single lab","pmids":["40542648"],"is_preprint":false},{"year":2025,"finding":"HELQ promotes replication fork reversal: HELQ and BCDX2 act epistatically to slow replication fork progression under replication stress (DNA fiber assay), and electron microscopy shows that reversed fork structures are reduced in HELQ-knockout cells. Biochemical reconstitution demonstrates HELQ is stimulated by RPA on fork substrates containing a leading-strand gap. HELQ deletion suppresses nascent strand degradation when BRCA2- or FANCD2-dependent fork protection is lost.","method":"DNA fiber assay, electron microscopy of replication intermediates, biochemical reconstitution with fork substrates, HELQ-KO epistasis with BRCA2/FANCD2","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — biochemical reconstitution plus EM structural visualization plus cell-based epistasis; multiple orthogonal methods converging on the same conclusion","pmids":["42055550"],"is_preprint":false},{"year":2008,"finding":"In C. elegans, hel-308 functions in ICL repair via a Fanconi anemia-dependent pathway, genetically distinct from polq-1/POLQ which operates through a brc-1 (CeBRCA1)-dependent pathway; epistatic and cytological analyses establish these as parallel mechanisms.","method":"C. elegans mutant survival assays, checkpoint/apoptosis cytology, genetic epistasis (hel-308 vs. FA pathway vs. polq-1/brc-1)","journal":"DNA repair","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean genetic epistasis in C. elegans with multiple phenotypic readouts; ortholog of human HELQ","pmids":["18472307"],"is_preprint":false},{"year":2016,"finding":"HELQ overexpression or knockdown in osteosarcoma cells alters expression of CHK1 and RAD51 proteins, with HELQ overexpression increasing CHK1 and RAD51 levels and reducing invasion/migration, while knockdown has the opposite effects. The antitumor activities of HELQ are associated with upregulation of CHK1-RAD51 signaling.","method":"shRNA knockdown and lentiviral overexpression, western blot, Transwell invasion, wound healing, Comet assay","journal":"Oncology reports","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single method set; pathway placement by expression-level correlation without direct mechanistic dissection","pmids":["28000895"],"is_preprint":false},{"year":2025,"finding":"HELQ promotes OC platinum resistance by upregulating PARP1 expression; HELQ overexpression increases PARP1 levels, and PARP1 downregulation reverses the HELQ-mediated resistance. HELQ overexpression also sensitizes OC cells to PARP inhibitors.","method":"HELQ overexpression/knockdown in cell lines, western blot (PARP1, γH2AX, RPA1, 53BP1), PARP1 knockdown rescue, CCK8 viability assay, in vivo xenograft","journal":"Translational oncology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, mechanism limited to expression-level changes in PARP1; no direct biochemical demonstration of interaction or direct regulation","pmids":["40381483"],"is_preprint":false}],"current_model":"HELQ is a conserved 3′→5′ superfamily 2 helicase whose PWI-like N-terminal domain recruits it to RPA-coated ssDNA at stalled replication forks and DSBs; once loaded, its helicase core translocates as a dimer, unwinding lagging-strand fork structures and D-loops, while a winged helix domain couples duplex DNA binding to stimulate this activity and domain V/motif IVa acts as a regulatory brake. HELQ also possesses RPA-stimulated DNA strand annealing activity, making it a dual-function enzyme whose two activities are antagonistically regulated by RPA (inhibits unwinding, stimulates annealing) and RAD51 (stimulates unwinding via direct complex formation). Through direct interaction with the RAD51 paralogue BCDX2 complex, HELQ promotes replication fork reversal and homologous recombination, functioning in parallel to the Fanconi anaemia pathway; it additionally supports single-strand annealing and microhomology-mediated end-joining, regulates EXO1-dependent end resection at DSBs, inhibits Pol δ DNA synthesis via its intrinsically disordered region (which also mediates a POLD3 interaction that stimulates annealing), resolves R-loops in coordination with XRN2, and in primordial germ cells suppresses LINE-1 retrotransposition by interacting with the KDM4B demethylase to maintain H3K9me3 at LINE-1 loci."},"narrative":{"mechanistic_narrative":"HELQ is a conserved superfamily 2 DNA helicase that maintains genome stability at stalled replication forks and double-strand breaks by coupling DNA unwinding to homologous recombination and fork protection [PMID:24005329, PMID:24005565, PMID:42055550]. Structural and biochemical work on the archaeal ortholog Hel308 established a five-domain helicase architecture in which a central pore lined with DNA-binding residues threads single-stranded DNA, a winged-helix domain couples duplex DNA binding to stimulate unwinding, and domain V plus a RecA2 motif IVa act as autoinhibitory 'molecular brakes' that tune both unwinding and strand-annealing output [PMID:18056710, PMID:28738244, PMID:37409572]. The enzyme requires a 3' single-stranded overhang to load and preferentially displaces lagging strands at fork structures and the invading strands of D-loops [PMID:15994460, PMID:21398521]; its N-terminal PWI-like domain mediates an RPA interaction that loads the helicase core onto RPA-coated ssDNA, after which it translocates as a dimer [PMID:34316696]. HELQ is a dual-function enzyme whose helicase and DNA strand-annealing activities are antagonistically regulated: RPA inhibits unwinding but stimulates annealing, whereas RAD51 forms a complex with HELQ and stimulates translocation [PMID:34937945]. Through direct interaction with the RAD51-paralogue BCDX2 complex it promotes homologous recombination and replication fork reversal, acting in parallel to the Fanconi anaemia pathway, and it additionally supports single-strand annealing and microhomology-mediated end-joining, regulates EXO1-dependent end resection, and inhibits Pol δ synthesis via an intrinsically disordered region that also binds POLD3 to stimulate annealing [PMID:24005329, PMID:24005041, PMID:34937945, PMID:36718939, PMID:37897354, PMID:42055550]. Beyond fork and break repair, HELQ resolves R-loops in coordination with the exoribonuclease XRN2 and, in primordial germ cells, suppresses LINE-1 retrotransposition by interacting with the KDM4B demethylase to preserve H3K9me3 at LINE-1 loci [PMID:39965657, PMID:40542648]. Helicase-deficient Helq mice show subfertility, germ cell attrition, interstrand crosslink sensitivity and tumour predisposition [PMID:24005329].","teleology":[{"year":2005,"claim":"Established that the HELQ ortholog acts directly at stalled replication forks, defining its core biological target before its mechanism was understood.","evidence":"In vivo E. coli dnaE synthetic lethality and in vitro helicase assays on fork and D-loop substrates with archaeal Hel308","pmids":["15994460"],"confidence":"High","gaps":["Archaeal system; human relevance not yet shown","Did not resolve loading or regulation"]},{"year":2007,"claim":"Resolved the structural basis of helicase action, showing a central DNA-binding pore and an autoinhibitory domain V brake that limits processivity.","evidence":"X-ray crystallography of S. solfataricus Hel308 with protein-displacement assays, plus domain V arginine mutagenesis with ATPase/unwinding assays","pmids":["18056710","17991488"],"confidence":"High","gaps":["Archaeal protein","Physiological trigger releasing the brake not defined"]},{"year":2010,"claim":"Identified RPA as a physical partner that loads the helicase rather than driving its catalytic mechanism, addressing how the enzyme is recruited to ssDNA.","evidence":"Co-IP/pulldown with motif mapping and helicase stimulation assays on archaeal Hel308","pmids":["21195035"],"confidence":"Medium","gaps":["Only modest (1.5-2x) stimulation","Archaeal C-terminal motif; human loading domain not yet mapped"]},{"year":2011,"claim":"Connected human HELQ to damaged forks in cells and reconstituted its substrate preference and RPA dependence, bridging archaeal mechanism to human biology.","evidence":"GFP live-cell imaging/co-localization with RAD51 and FANCD2 after camptothecin, plus in vitro helicase assays with human RPA","pmids":["21398521"],"confidence":"High","gaps":["Co-localization does not prove direct partner interactions","Annealing activity not yet appreciated"]},{"year":2013,"claim":"Placed HELQ in homologous recombination via direct BCDX2/RAD51-paralogue binding and ATR-CHK1 signaling, acting in parallel to the Fanconi anaemia pathway.","evidence":"Reciprocal Co-IP, co-IP/MS interactome, mouse knockouts, FANCD2 ubiquitination, and double-mutant epistasis (Helq;Fancc) with ICL phenotypes","pmids":["24005329","24005565","24005041"],"confidence":"High","gaps":["Molecular consequence of BCDX2 binding for unwinding not defined","Whether ATR effect is direct or downstream of recombination failure unclear"]},{"year":2017,"claim":"Defined the winged-helix domain as the module that couples duplex DNA binding to stimulate unwinding, refining the domain logic of the enzyme.","evidence":"WHD mutagenesis and isolated-domain DNA-binding/ATPase/helicase assays in Hel308 and human HelQ","pmids":["28738244"],"confidence":"High","gaps":["WHD contribution in full-length human HELQ in cells not tested"]},{"year":2019,"claim":"Demonstrated sequence-dependent translocation kinetics at single-base resolution, revealing how DNA sequence modulates the ATP cycle.","evidence":"Single-molecule SPRNT nanopore tweezers on archaeal Hel308","pmids":["30649515"],"confidence":"Medium","gaps":["Single lab, archaeal ortholog","Functional consequence in repair not addressed"]},{"year":2021,"claim":"Reframed HELQ as a dual-function enzyme whose unwinding and strand-annealing activities are antagonistically controlled by RPA and RAD51, and mapped the PWI-domain loading mechanism.","evidence":"Biochemical reconstitution, single-molecule imaging, and pathway-specific cell assays (SSA, MMEJ, gene conversion) plus domain mapping and dimeric translocation analysis","pmids":["34937945","34316696"],"confidence":"High","gaps":["Switch between annealase and helicase modes in vivo not directly observed","Stoichiometry of the HELQ-RAD51 complex unresolved"]},{"year":2022,"claim":"Distinguished HELQ's early role in forming recombination intermediates from BLM's later processing during synthesis-dependent strand annealing.","evidence":"Drosophila double-strand gap repair assays with blm helq and helq fancm double mutants","pmids":["35328029"],"confidence":"Medium","gaps":["Drosophila model","Molecular nature of the early intermediate not defined"]},{"year":2023,"claim":"Uncovered multiple non-canonical HELQ functions: a Pol δ-inhibiting/POLD3-binding intrinsically disordered region, control of EXO1 resection and fork protection with CtIP, a motif IVa catalytic switch, and a requirement in FANCD2-driven MiDAS.","evidence":"In vitro synthesis inhibition with domain-mapped mutants and POLD3 Co-IP; separation-of-function HELQ cells with resection/fiber/epistasis assays; motif IVa mutagenesis with MD simulations and archaeal recombination assay; MiDAS EdU assays","pmids":["36718939","37897354","37409572","37777152"],"confidence":"High","gaps":["How these activities are coordinated on a single fork is unclear","MiDAS step placement inferred as 'early' without full mechanism"]},{"year":2024,"claim":"Extended HELQ function to ssDNA gap processing and end-joining-driven mutagenesis, defining a HELQ-RAD52-BRCA axis and a role in psoralen ICL deletion repair.","evidence":"Genome-wide CRISPR screens with PRIMPOL overexpression and epistasis (HELQ/RAD52/BRCA); C. elegans hel-308 mutant whole-genome sequencing of repair products","pmids":["39530221","40082407"],"confidence":"Medium","gaps":["RAD52/BRCA axis placement partially inferential","Direct biochemical action on gaps not reconstituted"]},{"year":2025,"claim":"Demonstrated HELQ drives replication fork reversal with BCDX2 and broadened its scope to R-loop resolution with XRN2 and LINE-1 silencing via KDM4B/H3K9me3 in germ cells.","evidence":"DNA fiber, electron microscopy of reversed forks and reconstitution with leading-gap substrates; R-loop IF/in vitro resolution with catalytic-dead mutant and XRN2 Co-IP; Helq-KO PGCs with KDM4B Co-IP, H3K9me3 ChIP, and retrotransposition-inhibitor rescue","pmids":["42055550","39965657","40542648"],"confidence":"High","gaps":["Whether fork reversal, R-loop, and chromatin functions share one mechanism or are independent is unknown","KDM4B regulation mechanism by HELQ undefined"]},{"year":null,"claim":"How HELQ's helicase, annealase, fork-reversal, R-loop, and chromatin-silencing activities are partitioned and regulated across distinct genomic contexts in human cells remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of human HELQ bound to BCDX2 or RAD51","No unified model integrating annealase and helicase mode-switching in vivo","Disease/clinical roles rest on Low-confidence expression-correlation studies"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140097","term_label":"catalytic activity, acting on DNA","supporting_discovery_ids":[0,2,3,8,15,19]},{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[1,8,11,19]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[0,8,10,11]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[1,8,19]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[13,14]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[3,19,20]}],"pathway":[{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[5,6,7,10,14]},{"term_id":"R-HSA-69306","term_label":"DNA Replication","supporting_discovery_ids":[2,3,21]},{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[19]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[16,21]}],"complexes":["BCDX2 (RAD51 paralogue complex)"],"partners":["RPA","RAD51","BCDX2","POLD3","XRN2","KDM4B","EXO1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8TDG4","full_name":"Helicase POLQ-like","aliases":["Mus308-like helicase","POLQ-like helicase"],"length_aa":1101,"mass_kda":124.1,"function":"Single-stranded 3'-5' DNA helicase that plays a key role in homology-driven double-strand break (DSB) repair (PubMed:11751861, PubMed:19995904, PubMed:21398521, PubMed:24005041, PubMed:24005565, PubMed:34316696, PubMed:34937945). Involved in different DSB repair mechanisms that are guided by annealing of extensive stretches of complementary bases at break ends, such as microhomology-mediated end-joining (MMEJ), single-strand annealing (SSA) or synthesis-dependent strand annealing (SDSA) (PubMed:34937945). Possesses both DNA unwinding and annealing activities (PubMed:34937945). Forms a complex with RAD51, stimulating HELQ DNA helicase activity and ability to unwing DNA (PubMed:34937945). Efficiently unwinds substrates containing 3' overhangs or a D-loop (PubMed:21398521, PubMed:34937945). In contrast, interaction with the replication protein A (RPA/RP-A) complex inhibits DNA unwinding by HELQ but strongly stimulates DNA strand annealing (PubMed:34937945). Triggers displacement of RPA from single-stranded DNA to facilitate annealing of complementary sequences (PubMed:34316696, PubMed:34937945)","subcellular_location":"Nucleus; Chromosome","url":"https://www.uniprot.org/uniprotkb/Q8TDG4/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/HELQ","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/HELQ","total_profiled":1310},"omim":[{"mim_id":"618611","title":"HOMOLOGOUS RECOMBINATION FACTOR WITH OB-FOLD; HROB","url":"https://www.omim.org/entry/618611"},{"mim_id":"606769","title":"HELICASE, POLQ-LIKE; HELQ","url":"https://www.omim.org/entry/606769"},{"mim_id":"602954","title":"RAD51 PARALOG D; RAD51D","url":"https://www.omim.org/entry/602954"},{"mim_id":"602948","title":"RAD51 PARALOG B; RAD51B","url":"https://www.omim.org/entry/602948"},{"mim_id":"602774","title":"RAD51 PARALOG C; RAD51C","url":"https://www.omim.org/entry/602774"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nuclear speckles","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/HELQ"},"hgnc":{"alias_symbol":["Hel308"],"prev_symbol":[]},"alphafold":{"accession":"Q8TDG4","domains":[{"cath_id":"3.40.50.300","chopping":"316-517","consensus_level":"high","plddt":91.8803,"start":316,"end":517},{"cath_id":"3.40.50.300","chopping":"524-737","consensus_level":"high","plddt":90.6893,"start":524,"end":737},{"cath_id":"1.10.10.10","chopping":"753-831","consensus_level":"high","plddt":90.4076,"start":753,"end":831},{"cath_id":"-","chopping":"842-1085","consensus_level":"medium","plddt":91.2048,"start":842,"end":1085}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TDG4","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TDG4-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TDG4-F1-predicted_aligned_error_v6.png","plddt_mean":73.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=HELQ","jax_strain_url":"https://www.jax.org/strain/search?query=HELQ"},"sequence":{"accession":"Q8TDG4","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8TDG4.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8TDG4/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TDG4"}},"corpus_meta":[{"pmid":"24005329","id":"PMC_24005329","title":"HELQ promotes RAD51 paralogue-dependent repair to avert germ cell loss and tumorigenesis.","date":"2013","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/24005329","citation_count":87,"is_preprint":false},{"pmid":"18472307","id":"PMC_18472307","title":"Caenorhabditis elegans POLQ-1 and HEL-308 function in two distinct DNA interstrand cross-link repair pathways.","date":"2008","source":"DNA repair","url":"https://pubmed.ncbi.nlm.nih.gov/18472307","citation_count":86,"is_preprint":false},{"pmid":"18056710","id":"PMC_18056710","title":"Structure of the DNA repair helicase hel308 reveals DNA binding and autoinhibitory domains.","date":"2007","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18056710","citation_count":82,"is_preprint":false},{"pmid":"19525970","id":"PMC_19525970","title":"Structural evidence for consecutive Hel308-like modules in the spliceosomal ATPase Brr2.","date":"2009","source":"Nature structural & molecular 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ovarian cancer families.","date":"2016","source":"Familial cancer","url":"https://pubmed.ncbi.nlm.nih.gov/26351136","citation_count":9,"is_preprint":false},{"pmid":"27565320","id":"PMC_27565320","title":"HELQ in cancer and reproduction.","date":"2016","source":"Neoplasma","url":"https://pubmed.ncbi.nlm.nih.gov/27565320","citation_count":8,"is_preprint":false},{"pmid":"36718939","id":"PMC_36718939","title":"Interaction of human HelQ with DNA polymerase delta halts DNA synthesis and stimulates DNA single-strand annealing.","date":"2023","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/36718939","citation_count":8,"is_preprint":false},{"pmid":"35328029","id":"PMC_35328029","title":"Division of Labor by the HELQ, BLM, and FANCM Helicases during Homologous Recombination Repair in Drosophila melanogaster.","date":"2022","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/35328029","citation_count":8,"is_preprint":false},{"pmid":"37777152","id":"PMC_37777152","title":"Mitotic DNA Synthesis in Untransformed Human Cells Preserves Common Fragile Site Stability via a FANCD2-Driven Mechanism That Requires HELQ.","date":"2023","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/37777152","citation_count":8,"is_preprint":false},{"pmid":"37897354","id":"PMC_37897354","title":"Human HELQ regulates DNA end resection at DNA double-strand breaks and stalled replication forks.","date":"2023","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/37897354","citation_count":7,"is_preprint":false},{"pmid":"34672775","id":"PMC_34672775","title":"Identification and Functional Investigation of Novel Heterozygous HELQ Mutations in Patients with Sertoli Cell-only Syndrome.","date":"2021","source":"Genetic testing and molecular biomarkers","url":"https://pubmed.ncbi.nlm.nih.gov/34672775","citation_count":7,"is_preprint":false},{"pmid":"28101207","id":"PMC_28101207","title":"Structure-function analysis of DNA helicase HELQ: A new diagnostic marker in ovarian cancer.","date":"2016","source":"Oncology letters","url":"https://pubmed.ncbi.nlm.nih.gov/28101207","citation_count":6,"is_preprint":false},{"pmid":"37409572","id":"PMC_37409572","title":"Archaeal Hel308 suppresses recombination through a catalytic switch that controls DNA annealing.","date":"2023","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/37409572","citation_count":5,"is_preprint":false},{"pmid":"26190809","id":"PMC_26190809","title":"The screening of HELQ gene in Chinese patients with premature ovarian failure.","date":"2015","source":"Reproductive biomedicine online","url":"https://pubmed.ncbi.nlm.nih.gov/26190809","citation_count":5,"is_preprint":false},{"pmid":"36183369","id":"PMC_36183369","title":"HELQ suppresses migration and proliferation of non-small cell lung cancer cells by repairing DNA damage and inducing necrosis.","date":"2022","source":"Cell biology international","url":"https://pubmed.ncbi.nlm.nih.gov/36183369","citation_count":4,"is_preprint":false},{"pmid":"38500564","id":"PMC_38500564","title":"Evolutionary and functional insights into the Ski2-like helicase family in Archaea: a comparison of Thermococcales ASH-Ski2 and Hel308 activities.","date":"2024","source":"NAR genomics and bioinformatics","url":"https://pubmed.ncbi.nlm.nih.gov/38500564","citation_count":4,"is_preprint":false},{"pmid":"40082407","id":"PMC_40082407","title":"FAN1-mediated translesion synthesis and POLQ/HELQ-mediated end joining generate interstrand crosslink-induced mutations.","date":"2025","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/40082407","citation_count":3,"is_preprint":false},{"pmid":"40381483","id":"PMC_40381483","title":"HELQ upregulates PARP1 to drive platinum resistance and predict therapeutic response in ovarian cancer.","date":"2025","source":"Translational oncology","url":"https://pubmed.ncbi.nlm.nih.gov/40381483","citation_count":3,"is_preprint":false},{"pmid":"32895148","id":"PMC_32895148","title":"[Expressions of HELQ and RAD51C in endometrial stromal sarcoma and their clinical significance].","date":"2020","source":"Nan fang yi ke da xue xue bao = Journal of Southern Medical University","url":"https://pubmed.ncbi.nlm.nih.gov/32895148","citation_count":3,"is_preprint":false},{"pmid":"39530221","id":"PMC_39530221","title":"CRISPR knockout genome-wide screens identify the HELQ-RAD52 axis in regulating the repair of cisplatin-induced single-stranded DNA gaps.","date":"2024","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/39530221","citation_count":3,"is_preprint":false},{"pmid":"39965657","id":"PMC_39965657","title":"The human HELQ helicase and XRN2 exoribonuclease cooperate in R-loop resolution.","date":"2025","source":"Open biology","url":"https://pubmed.ncbi.nlm.nih.gov/39965657","citation_count":2,"is_preprint":false},{"pmid":"38659927","id":"PMC_38659927","title":"CRISPR knockout genome-wide screens identify the HELQ-RAD52 axis in regulating the repair of cisplatin-induced single stranded DNA gaps.","date":"2024","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/38659927","citation_count":2,"is_preprint":false},{"pmid":"39201320","id":"PMC_39201320","title":"Helicase HELQ: Molecular Characters Fit for DSB Repair Function.","date":"2024","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/39201320","citation_count":1,"is_preprint":false},{"pmid":"40542648","id":"PMC_40542648","title":"HELQ Maintains Genome Stability of Primordial Germ Cells by Inhibiting LINE-1 Expression.","date":"2025","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/40542648","citation_count":0,"is_preprint":false},{"pmid":"38720471","id":"PMC_38720471","title":"HELQ deficiency impairs the induction of primordial germ cell-like cells.","date":"2024","source":"FEBS open bio","url":"https://pubmed.ncbi.nlm.nih.gov/38720471","citation_count":0,"is_preprint":false},{"pmid":"38540391","id":"PMC_38540391","title":"A Human Homozygous HELQ Missense Variant Does Not Cause Premature Ovarian Insufficiency in a Mouse Model.","date":"2024","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/38540391","citation_count":0,"is_preprint":false},{"pmid":"42055550","id":"PMC_42055550","title":"The DNA helicase HELQ promotes replication fork reversal in coordination with BRCA2- and FANCD2-mediated repair pathways.","date":"2026","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/42055550","citation_count":0,"is_preprint":false},{"pmid":"40176377","id":"PMC_40176377","title":"Correction to \"HELQ deficiency impairs the induction of primordial germ cell-like cells\".","date":"2025","source":"FEBS open bio","url":"https://pubmed.ncbi.nlm.nih.gov/40176377","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":19939,"output_tokens":6505,"usd":0.078696,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":15558,"output_tokens":4319,"usd":0.092883,"stage2_stop_reason":"end_turn"},"total_usd":0.171579,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"Crystal structure of archaeal Hel308 (Sulfolobus solfataricus) reveals a five-domain architecture with a central pore lined with essential DNA-binding residues; domain V acts as an autoinhibitory 'molecular brake' that clamps single-stranded DNA extruded through the central pore, limiting helicase processivity. Hel308 can displace streptavidin from biotinylated DNA, and this protein-displacement activity is only partially inhibited by RPA or Alba1 pre-bound to DNA, while RadA pre-binding has no effect.\",\n      \"method\": \"X-ray crystallography (high-resolution crystal structure), in vitro helicase/protein-displacement assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with functional validation by in vitro assays; multiple orthogonal methods in one study\",\n      \"pmids\": [\"18056710\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Mutagenesis of three arginine residues in domain V of archaeal Hel308 demonstrates that domain V couples DNA binding to ATP hydrolysis and positions single-stranded DNA relative to the helicase ratchet domain IV for efficient fork unwinding.\",\n      \"method\": \"Site-directed mutagenesis, in vitro ATPase assay, DNA-binding and unwinding assays\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — active-site mutagenesis combined with multiple in vitro biochemical assays in a single focused study\",\n      \"pmids\": [\"17991488\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Archaeal Hel308 targets stalled replication forks in vivo (introduction into E. coli dnaE strains causes synthetic lethality, phenocopying RecQ) and in vitro specifically displaces lagging strands from fork structures; it also targets the invading strand of D-loops.\",\n      \"method\": \"In vivo genetic complementation (E. coli dnaE conditional lethality), in vitro helicase assays on replication fork and D-loop substrates\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro biochemical assay combined with in vivo genetic epistasis; multiple orthogonal approaches\",\n      \"pmids\": [\"15994460\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Human HEL308 (HELQ) localizes to damaged replication forks after camptothecin treatment, co-localizing with RAD51 and FANCD2. Purified HEL308 requires a 3′ single-stranded overhang to load onto DNA, preferentially unwinds the parental strands of a model stalled fork with a nascent lagging strand, and its unwinding activity is specifically stimulated by human RPA.\",\n      \"method\": \"GFP-tag live-cell imaging and co-localization, in vitro helicase assays with purified proteins, RPA stimulation assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — direct localization experiment with functional consequence, combined with in vitro biochemical reconstitution; multiple orthogonal methods\",\n      \"pmids\": [\"21398521\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Archaeal Hel308 physically interacts with RPA (but not SSB); interaction requires a conserved amino acid motif at the Hel308 C-terminus. RPA modestly stimulates Hel308 helicase activity (1.5–2 fold), supporting a model in which RPA loads Hel308 onto ssDNA at blocked replication forks rather than directly stimulating its unwinding mechanism.\",\n      \"method\": \"Co-immunoprecipitation / pulldown assays, deletion/mutation mapping, in vitro helicase stimulation assays\",\n      \"journal\": \"DNA repair\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — physical interaction mapped by pulldown with motif mapping, plus functional helicase stimulation assay; single lab\",\n      \"pmids\": [\"21195035\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"HELQ directly interacts with the RAD51 paralogue complex BCDX2 and functions in parallel to the Fanconi anaemia pathway to promote homologous recombination at damaged replication forks. Helicase-deficient Helq mice show subfertility, germ cell attrition, ICL sensitivity and tumour predisposition.\",\n      \"method\": \"Co-immunoprecipitation (direct interaction with BCDX2), mouse knockout phenotyping, epistasis with FA pathway\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP establishing direct interaction, in vivo mouse model with defined phenotypic readouts, and genetic epistasis placing HELQ parallel to FA pathway; multiple orthogonal approaches across labs\",\n      \"pmids\": [\"24005329\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Human HELQ is associated with RAD51 paralogs RAD51B/C/D and XRCC2, and with the DNA damage-responsive kinase ATR, as revealed by proteomic analysis. HELQ knockout in human cells enhances sensitivity to mitomycin C and chromosome radial formation, and reduces CHK1 phosphorylation after MMC treatment, indicating HELQ participates in ATR-CHK1 signaling in response to ICL.\",\n      \"method\": \"Proteomic analysis (co-IP/MS), HELQ knockout in human cells, MMC sensitivity assay, immunoblot for CHK1 phosphorylation\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — proteomic interactome plus functional KO phenotype with signaling readout; two independent Nature-family papers in same year converge on RAD51 paralog interaction\",\n      \"pmids\": [\"24005565\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Helq acts in parallel (non-epistatic) to Fancc in suppressing spontaneous chromosome instability (micronuclei, 53BP1 nuclear bodies) and ICL sensitivity in mice; Helq-deficient cells have intact FANCD2 mono-ubiquitination and focus formation, placing HELQ outside the canonical FA core complex pathway.\",\n      \"method\": \"Mouse double mutant (Helqgt/gt; Fancc−/−) epistasis analysis, FANCD2 ubiquitination assay, cytogenetic analysis\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic epistasis with double-mutant mice and multiple cellular phenotype readouts; independent of the two 2013 Nature/Nature Comm papers\",\n      \"pmids\": [\"24005041\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"The winged helix domain (WHD) of Hel308 promotes DNA binding and unwinding: mutations in a solvent-exposed α-helix of the WHD reduce DNA binding and unwinding. Isolated WHD binds duplex DNA but not ssDNA, and disrupting the interface between the WHD and the RecA-like domain abolishes ATPase and helicase activities. The isolated WHD of human HelQ also binds duplex DNA.\",\n      \"method\": \"Site-directed mutagenesis, in vitro DNA-binding assays, ATPase assay, helicase assay with isolated domain constructs\",\n      \"journal\": \"DNA repair\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — active-site/domain mutagenesis combined with multiple in vitro biochemical assays; isolated domain analysis confirms functional role\",\n      \"pmids\": [\"28738244\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Single-molecule nanopore tweezers (SPRNT) reveal that DNA bases at two specific sites within Hel308 control the kinetics of an ATP-independent step in the ATP hydrolysis cycle, demonstrating sequence-specific translocation kinetics during ssDNA translocation.\",\n      \"method\": \"Single-molecule SPRNT (picometer-resolution nanopore tweezers)\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — novel single-molecule method with high resolution; single lab, single study on archaeal ortholog\",\n      \"pmids\": [\"30649515\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HELQ possesses both helicase and DNA strand annealing activities that are differentially regulated: RAD51 forms a complex with HELQ and strongly stimulates its translocation/unwinding activity, whereas RPA inhibits DNA unwinding but strongly stimulates DNA strand annealing. HELQ can capture RPA-bound ssDNA strands and displace RPA to facilitate annealing of complementary sequences. HELQ deficiency impairs single-strand annealing (SSA) and microhomology-mediated end-joining (MMEJ) pathways and biases towards long-tract gene conversion during homologous recombination.\",\n      \"method\": \"Biochemical reconstitution, single-molecule imaging, HELQ-deficient cell lines with specific pathway assays (SSA, MMEJ, gene conversion tract analysis)\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — biochemical reconstitution combined with single-molecule imaging and cell-based pathway-specific assays; multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"34937945\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The N-terminal non-catalytic region of human HelQ contains a PWI-like domain that mediates interaction with RPA to orchestrate loading of HelQ helicase domains onto ssDNA. Once loaded, HelQ translocates along ssDNA as a dimer, activated by ATP-Mg2+ binding at the catalytic site. Specific HelQ-ssDNA interactions critical for the translocation mechanism were identified.\",\n      \"method\": \"Domain characterization with deletion constructs, RPA interaction assays (pulldown), in vitro helicase/translocation assays, mutagenesis of ssDNA contact residues\",\n      \"journal\": \"NAR cancer\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — multiple biochemical methods including domain mapping, pulldown interaction, and translocation assays; identifies new functional domain with mechanistic follow-up\",\n      \"pmids\": [\"34316696\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"In Drosophila, HELQ, BLM, and FANCM helicases play distinct roles during synthesis-dependent strand annealing (SDSA): double mutants (blm helq and helq fancm) show more severe SDSA defects than single mutants, and HELQ and FANCM act early to promote formation of recombination intermediates that are then processed by BLM to prevent deletion-prone repair.\",\n      \"method\": \"Drosophila genetic double-strand gap repair assay, double mutant epistasis analysis\",\n      \"journal\": \"Genes\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with defined HR pathway readout in Drosophila; double mutant analysis; consistent with mammalian data\",\n      \"pmids\": [\"35328029\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Human HelQ halts DNA synthesis by DNA polymerase delta (Pol δ) and Pol δ-PCNA-RPA holoenzyme; this inhibition is independent of HelQ DNA binding and maps to a 70-amino-acid intrinsically disordered region of HelQ. POLD3 subunit of Pol δ physically interacts with HelQ via this intrinsically disordered region and strongly stimulates HelQ DNA strand annealing activity. HelQ cannot inhibit the isolated POLD1 catalytic subunit alone.\",\n      \"method\": \"In vitro DNA synthesis inhibition assays, novel HelQ mutant proteins, pulldown/Co-IP (POLD3-HelQ interaction), DNA strand annealing assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with domain-mapped mutants; identifies physical interaction and functional consequence; multiple orthogonal biochemical approaches\",\n      \"pmids\": [\"36718939\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"HELQ helicase activity is required for EXO1-mediated DNA end resection at double-strand breaks (DSBs), while the ssDNA-binding capacity of HELQ is required for its recruitment to stalled replication forks, where it facilitates fork protection and prevents chromosome aberrations. HELQ synergizes with CtIP (but not BRCA1 or BRCA2) to protect stalled forks.\",\n      \"method\": \"HELQ knockout/mutant cells, resection assays (RPA/ssDNA accumulation), replication fork protection assays (DNA fiber), epistasis with CtIP/BRCA1/BRCA2, chromosome aberration analysis\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-based functional assays with separation-of-function mutants and genetic epistasis; single lab\",\n      \"pmids\": [\"37897354\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"A conserved motif IVa (F/YHHAGL) in the RecA2 domain of archaeal Hel308/HELQ acts as a catalytic switch modulating both DNA unwinding and strand annealing: a single amino acid substitution in motif IVa produces hyper-active helicase and annealase activities in vitro and causes a 160,000-fold increase in gene conversion (non-crossover) recombination in archaeal cells, while crossover recombination is unaffected.\",\n      \"method\": \"Site-directed mutagenesis, in vitro helicase and strand-annealing assays, all-atom molecular dynamics simulations, in vivo recombination assay in archaea\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — active-site mutagenesis, in vitro biochemical reconstitution, MD simulations, and in vivo genetic assay provide convergent multi-method evidence\",\n      \"pmids\": [\"37409572\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"FANCD2-driven mitotic DNA synthesis (MiDAS) in untransformed human cells requires HELQ, which functions at an early step of this pathway; FANCD2 mono-ubiquitination by FA proteins is a prerequisite step upstream.\",\n      \"method\": \"HELQ-deficient cell analysis, MiDAS assay (EdU incorporation on metaphase chromosomes), genetic epistasis with FA pathway components\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — cell-based MiDAS assay with HELQ-deficient cells and FA epistasis; single lab; step placement is inferred as 'early' without full mechanistic resolution\",\n      \"pmids\": [\"37777152\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In C. elegans, HELQ (hel-308) participates in end-joining during ICL repair, contributing to deletion formation at psoralen ICL sites; this is distinct from translesion synthesis-driven SNV formation mediated by POLH/REV1/3.\",\n      \"method\": \"C. elegans mutant analysis, whole-genome sequencing of repair products, epistasis with FA pathway (FANCD2, FANCI), TRAIP and FAN1 genetic analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with mutational signature readout; multi-gene analysis in C. elegans model; convergent with prior ICL repair role\",\n      \"pmids\": [\"40082407\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"HELQ specifically suppresses cisplatin sensitivity caused by PRIMPOL-generated ssDNA gaps, with this suppression associated with reduced ssDNA accumulation. RAD52 acts as a mediator downstream; RAD52 promotes ssDNA gap accumulation through a BRCA-mediated mechanism, defining a HELQ–RAD52–BRCA axis in ssDNA gap processing.\",\n      \"method\": \"CRISPR genome-wide knockout screens, PRIMPOL-overexpression model, ssDNA accumulation assays, genetic epistasis (HELQ/RAD52/BRCA)\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genome-wide CRISPR screen followed by targeted epistasis validation; multiple methods but pathway placement partially inferential\",\n      \"pmids\": [\"39530221\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HELQ is recruited by RPA at R-loops and resolves R-loops in a manner dependent on its ATPase/helicase catalytic activity. HELQ functionally interacts with the nuclear 5'–3' exoribonuclease XRN2, coordinating R-loop unwinding (by HELQ) with RNA digestion (by XRN2).\",\n      \"method\": \"Cell-based R-loop assays (S9.6 immunofluorescence), in vitro R-loop resolution assay with purified proteins, co-IP (HELQ–XRN2 interaction), catalytic-dead HELQ mutant\",\n      \"journal\": \"Open biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-based and in vitro assays combined with Co-IP; catalytic-dead mutant validates mechanism; single lab\",\n      \"pmids\": [\"39965657\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HELQ interacts with the H3K9me3 demethylase KDM4B in primordial germ cells (PGCs); HELQ deficiency increases total and chromatin-bound KDM4B levels, reducing H3K9me3 at LINE-1 retrotransposon regions, which triggers LINE-1 expression and DNA damage accumulation in PGCs. Retrotransposition inhibition rescues the developmental defects of HELQ-deficient PGCs.\",\n      \"method\": \"Mouse Helq knockout, Co-IP (HELQ–KDM4B interaction), ChIP (H3K9me3 at LINE-1), retrotransposition inhibitor rescue experiment, PGC proliferation assays\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP identifies new interaction, ChIP links it to chromatin mechanism, and pharmacological rescue validates pathway; single lab\",\n      \"pmids\": [\"40542648\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HELQ promotes replication fork reversal: HELQ and BCDX2 act epistatically to slow replication fork progression under replication stress (DNA fiber assay), and electron microscopy shows that reversed fork structures are reduced in HELQ-knockout cells. Biochemical reconstitution demonstrates HELQ is stimulated by RPA on fork substrates containing a leading-strand gap. HELQ deletion suppresses nascent strand degradation when BRCA2- or FANCD2-dependent fork protection is lost.\",\n      \"method\": \"DNA fiber assay, electron microscopy of replication intermediates, biochemical reconstitution with fork substrates, HELQ-KO epistasis with BRCA2/FANCD2\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — biochemical reconstitution plus EM structural visualization plus cell-based epistasis; multiple orthogonal methods converging on the same conclusion\",\n      \"pmids\": [\"42055550\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"In C. elegans, hel-308 functions in ICL repair via a Fanconi anemia-dependent pathway, genetically distinct from polq-1/POLQ which operates through a brc-1 (CeBRCA1)-dependent pathway; epistatic and cytological analyses establish these as parallel mechanisms.\",\n      \"method\": \"C. elegans mutant survival assays, checkpoint/apoptosis cytology, genetic epistasis (hel-308 vs. FA pathway vs. polq-1/brc-1)\",\n      \"journal\": \"DNA repair\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic epistasis in C. elegans with multiple phenotypic readouts; ortholog of human HELQ\",\n      \"pmids\": [\"18472307\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"HELQ overexpression or knockdown in osteosarcoma cells alters expression of CHK1 and RAD51 proteins, with HELQ overexpression increasing CHK1 and RAD51 levels and reducing invasion/migration, while knockdown has the opposite effects. The antitumor activities of HELQ are associated with upregulation of CHK1-RAD51 signaling.\",\n      \"method\": \"shRNA knockdown and lentiviral overexpression, western blot, Transwell invasion, wound healing, Comet assay\",\n      \"journal\": \"Oncology reports\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single method set; pathway placement by expression-level correlation without direct mechanistic dissection\",\n      \"pmids\": [\"28000895\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"HELQ promotes OC platinum resistance by upregulating PARP1 expression; HELQ overexpression increases PARP1 levels, and PARP1 downregulation reverses the HELQ-mediated resistance. HELQ overexpression also sensitizes OC cells to PARP inhibitors.\",\n      \"method\": \"HELQ overexpression/knockdown in cell lines, western blot (PARP1, γH2AX, RPA1, 53BP1), PARP1 knockdown rescue, CCK8 viability assay, in vivo xenograft\",\n      \"journal\": \"Translational oncology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, mechanism limited to expression-level changes in PARP1; no direct biochemical demonstration of interaction or direct regulation\",\n      \"pmids\": [\"40381483\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"HELQ is a conserved 3′→5′ superfamily 2 helicase whose PWI-like N-terminal domain recruits it to RPA-coated ssDNA at stalled replication forks and DSBs; once loaded, its helicase core translocates as a dimer, unwinding lagging-strand fork structures and D-loops, while a winged helix domain couples duplex DNA binding to stimulate this activity and domain V/motif IVa acts as a regulatory brake. HELQ also possesses RPA-stimulated DNA strand annealing activity, making it a dual-function enzyme whose two activities are antagonistically regulated by RPA (inhibits unwinding, stimulates annealing) and RAD51 (stimulates unwinding via direct complex formation). Through direct interaction with the RAD51 paralogue BCDX2 complex, HELQ promotes replication fork reversal and homologous recombination, functioning in parallel to the Fanconi anaemia pathway; it additionally supports single-strand annealing and microhomology-mediated end-joining, regulates EXO1-dependent end resection at DSBs, inhibits Pol δ DNA synthesis via its intrinsically disordered region (which also mediates a POLD3 interaction that stimulates annealing), resolves R-loops in coordination with XRN2, and in primordial germ cells suppresses LINE-1 retrotransposition by interacting with the KDM4B demethylase to maintain H3K9me3 at LINE-1 loci.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"HELQ is a conserved superfamily 2 DNA helicase that maintains genome stability at stalled replication forks and double-strand breaks by coupling DNA unwinding to homologous recombination and fork protection [#5, #6, #21]. Structural and biochemical work on the archaeal ortholog Hel308 established a five-domain helicase architecture in which a central pore lined with DNA-binding residues threads single-stranded DNA, a winged-helix domain couples duplex DNA binding to stimulate unwinding, and domain V plus a RecA2 motif IVa act as autoinhibitory 'molecular brakes' that tune both unwinding and strand-annealing output [#0, #8, #15]. The enzyme requires a 3' single-stranded overhang to load and preferentially displaces lagging strands at fork structures and the invading strands of D-loops [#2, #3]; its N-terminal PWI-like domain mediates an RPA interaction that loads the helicase core onto RPA-coated ssDNA, after which it translocates as a dimer [#11]. HELQ is a dual-function enzyme whose helicase and DNA strand-annealing activities are antagonistically regulated: RPA inhibits unwinding but stimulates annealing, whereas RAD51 forms a complex with HELQ and stimulates translocation [#10]. Through direct interaction with the RAD51-paralogue BCDX2 complex it promotes homologous recombination and replication fork reversal, acting in parallel to the Fanconi anaemia pathway, and it additionally supports single-strand annealing and microhomology-mediated end-joining, regulates EXO1-dependent end resection, and inhibits Pol \\u03b4 synthesis via an intrinsically disordered region that also binds POLD3 to stimulate annealing [#5, #7, #10, #13, #14, #21]. Beyond fork and break repair, HELQ resolves R-loops in coordination with the exoribonuclease XRN2 and, in primordial germ cells, suppresses LINE-1 retrotransposition by interacting with the KDM4B demethylase to preserve H3K9me3 at LINE-1 loci [#19, #20]. Helicase-deficient Helq mice show subfertility, germ cell attrition, interstrand crosslink sensitivity and tumour predisposition [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2005,\n      \"claim\": \"Established that the HELQ ortholog acts directly at stalled replication forks, defining its core biological target before its mechanism was understood.\",\n      \"evidence\": \"In vivo E. coli dnaE synthetic lethality and in vitro helicase assays on fork and D-loop substrates with archaeal Hel308\",\n      \"pmids\": [\"15994460\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Archaeal system; human relevance not yet shown\", \"Did not resolve loading or regulation\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Resolved the structural basis of helicase action, showing a central DNA-binding pore and an autoinhibitory domain V brake that limits processivity.\",\n      \"evidence\": \"X-ray crystallography of S. solfataricus Hel308 with protein-displacement assays, plus domain V arginine mutagenesis with ATPase/unwinding assays\",\n      \"pmids\": [\"18056710\", \"17991488\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Archaeal protein\", \"Physiological trigger releasing the brake not defined\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identified RPA as a physical partner that loads the helicase rather than driving its catalytic mechanism, addressing how the enzyme is recruited to ssDNA.\",\n      \"evidence\": \"Co-IP/pulldown with motif mapping and helicase stimulation assays on archaeal Hel308\",\n      \"pmids\": [\"21195035\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Only modest (1.5-2x) stimulation\", \"Archaeal C-terminal motif; human loading domain not yet mapped\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Connected human HELQ to damaged forks in cells and reconstituted its substrate preference and RPA dependence, bridging archaeal mechanism to human biology.\",\n      \"evidence\": \"GFP live-cell imaging/co-localization with RAD51 and FANCD2 after camptothecin, plus in vitro helicase assays with human RPA\",\n      \"pmids\": [\"21398521\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Co-localization does not prove direct partner interactions\", \"Annealing activity not yet appreciated\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Placed HELQ in homologous recombination via direct BCDX2/RAD51-paralogue binding and ATR-CHK1 signaling, acting in parallel to the Fanconi anaemia pathway.\",\n      \"evidence\": \"Reciprocal Co-IP, co-IP/MS interactome, mouse knockouts, FANCD2 ubiquitination, and double-mutant epistasis (Helq;Fancc) with ICL phenotypes\",\n      \"pmids\": [\"24005329\", \"24005565\", \"24005041\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular consequence of BCDX2 binding for unwinding not defined\", \"Whether ATR effect is direct or downstream of recombination failure unclear\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defined the winged-helix domain as the module that couples duplex DNA binding to stimulate unwinding, refining the domain logic of the enzyme.\",\n      \"evidence\": \"WHD mutagenesis and isolated-domain DNA-binding/ATPase/helicase assays in Hel308 and human HelQ\",\n      \"pmids\": [\"28738244\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"WHD contribution in full-length human HELQ in cells not tested\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstrated sequence-dependent translocation kinetics at single-base resolution, revealing how DNA sequence modulates the ATP cycle.\",\n      \"evidence\": \"Single-molecule SPRNT nanopore tweezers on archaeal Hel308\",\n      \"pmids\": [\"30649515\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, archaeal ortholog\", \"Functional consequence in repair not addressed\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Reframed HELQ as a dual-function enzyme whose unwinding and strand-annealing activities are antagonistically controlled by RPA and RAD51, and mapped the PWI-domain loading mechanism.\",\n      \"evidence\": \"Biochemical reconstitution, single-molecule imaging, and pathway-specific cell assays (SSA, MMEJ, gene conversion) plus domain mapping and dimeric translocation analysis\",\n      \"pmids\": [\"34937945\", \"34316696\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Switch between annealase and helicase modes in vivo not directly observed\", \"Stoichiometry of the HELQ-RAD51 complex unresolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Distinguished HELQ's early role in forming recombination intermediates from BLM's later processing during synthesis-dependent strand annealing.\",\n      \"evidence\": \"Drosophila double-strand gap repair assays with blm helq and helq fancm double mutants\",\n      \"pmids\": [\"35328029\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Drosophila model\", \"Molecular nature of the early intermediate not defined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Uncovered multiple non-canonical HELQ functions: a Pol \\u03b4-inhibiting/POLD3-binding intrinsically disordered region, control of EXO1 resection and fork protection with CtIP, a motif IVa catalytic switch, and a requirement in FANCD2-driven MiDAS.\",\n      \"evidence\": \"In vitro synthesis inhibition with domain-mapped mutants and POLD3 Co-IP; separation-of-function HELQ cells with resection/fiber/epistasis assays; motif IVa mutagenesis with MD simulations and archaeal recombination assay; MiDAS EdU assays\",\n      \"pmids\": [\"36718939\", \"37897354\", \"37409572\", \"37777152\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How these activities are coordinated on a single fork is unclear\", \"MiDAS step placement inferred as 'early' without full mechanism\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extended HELQ function to ssDNA gap processing and end-joining-driven mutagenesis, defining a HELQ-RAD52-BRCA axis and a role in psoralen ICL deletion repair.\",\n      \"evidence\": \"Genome-wide CRISPR screens with PRIMPOL overexpression and epistasis (HELQ/RAD52/BRCA); C. elegans hel-308 mutant whole-genome sequencing of repair products\",\n      \"pmids\": [\"39530221\", \"40082407\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"RAD52/BRCA axis placement partially inferential\", \"Direct biochemical action on gaps not reconstituted\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Demonstrated HELQ drives replication fork reversal with BCDX2 and broadened its scope to R-loop resolution with XRN2 and LINE-1 silencing via KDM4B/H3K9me3 in germ cells.\",\n      \"evidence\": \"DNA fiber, electron microscopy of reversed forks and reconstitution with leading-gap substrates; R-loop IF/in vitro resolution with catalytic-dead mutant and XRN2 Co-IP; Helq-KO PGCs with KDM4B Co-IP, H3K9me3 ChIP, and retrotransposition-inhibitor rescue\",\n      \"pmids\": [\"42055550\", \"39965657\", \"40542648\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether fork reversal, R-loop, and chromatin functions share one mechanism or are independent is unknown\", \"KDM4B regulation mechanism by HELQ undefined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How HELQ's helicase, annealase, fork-reversal, R-loop, and chromatin-silencing activities are partitioned and regulated across distinct genomic contexts in human cells remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structure of human HELQ bound to BCDX2 or RAD51\", \"No unified model integrating annealase and helicase mode-switching in vivo\", \"Disease/clinical roles rest on Low-confidence expression-correlation studies\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140097\", \"supporting_discovery_ids\": [0, 2, 3, 8, 15, 19]},\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [1, 8, 11, 19]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [0, 8, 10, 11]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [1, 8, 19]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [13, 14]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [3, 19, 20]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [5, 6, 7, 10, 14]},\n      {\"term_id\": \"R-HSA-69306\", \"supporting_discovery_ids\": [2, 3, 21]},\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [19]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [16, 21]}\n    ],\n    \"complexes\": [\"BCDX2 (RAD51 paralogue complex)\"],\n    \"partners\": [\"RPA\", \"RAD51\", \"BCDX2\", \"POLD3\", \"XRN2\", \"KDM4B\", \"EXO1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}