{"gene":"POP4","run_date":"2026-04-28T19:45:44","timeline":{"discoveries":[{"year":1999,"finding":"Rpp29 (human homolog of yeast Pop4p) is a protein subunit of human RNase P; antibodies against recombinant Rpp29 precipitate catalytically active RNase P from HeLa cells, establishing it as part of the active enzyme complex.","method":"Immunoprecipitation of catalytically active RNase P with polyclonal antibodies against recombinant Rpp29","journal":"RNA (New York, N.Y.)","confidence":"Medium","confidence_rationale":"Tier 2 — reciprocal immunoprecipitation of active enzyme, single lab","pmids":["10024167"],"is_preprint":false},{"year":2003,"finding":"The archaeal Rpp29 homolog (Mth Rpp29/Mth11) adopts an oligonucleotide/oligosaccharide binding (OB) fold with a beta-barrel core and flexible N- and C-terminal extensions; it is an essential protein component of the archaeal RNase P holoenzyme as shown by reconstitution experiments, and NMR chemical shift perturbation identified its RNA-binding interface with the full RNase P RNA subunit.","method":"Solution NMR structure determination; reconstitution of archaeal RNase P holoenzyme from recombinant components; NMR chemical shift perturbation with full RNA subunit","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — NMR structure plus in vitro reconstitution demonstrating essentiality, multiple orthogonal methods","pmids":["14673079"],"is_preprint":false},{"year":2003,"finding":"The archaeal Rpp29 homolog from Archaeoglobus fulgidus forms a six-stranded antiparallel beta-sheet structure with flexible N- and C-terminal tails; conserved surface residues in loop regions (beta2-beta3, beta4-beta5) and the flexible tails are likely RNA- and protein-interaction surfaces, consistent with the structural homology to Pop4p.","method":"Multidimensional NMR structure determination; amide proton exchange and 15N relaxation rate measurements","journal":"Biochemistry","confidence":"Medium","confidence_rationale":"Tier 1 — NMR structure with dynamics data, single lab","pmids":["14622001"],"is_preprint":false},{"year":2004,"finding":"Crystal structure of the archaeal Rpp29 homolog Ph1771p at 2.0 Å resolution revealed an OB-fold beta-barrel with two potential RNA-binding sites: a concave surface with clustered positive charges and a loop region (beta2-beta3) with conserved hydrophilic residues that interact with sulfate ion; strand beta7 mediates protein-protein interactions via intermolecular antiparallel beta-sheet contacts.","method":"X-ray crystallography at 2.0 Å resolution; structural comparison","journal":"RNA (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1 — high-resolution crystal structure with structural analysis of interaction surfaces","pmids":["15317976"],"is_preprint":false},{"year":2008,"finding":"The archaeal homologs of Rpp21 and Rpp29 (PhoRpp21 and PhoRpp29) form a heterodimer whose crystal structure shows that the two N-terminal helices of PhoRpp21 interact with the N-terminal extension, beta-strand beta2, and C-terminal helix of PhoRpp29 via hydrogen bonds and salt bridges; mutational analysis confirmed that heterodimerization is important for RNase P function, and the complex displays a positively charged RNA-binding surface.","method":"Crystal structure determination of PhoRpp21-PhoRpp29 complex; mutational analysis of interface residues","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 — crystal structure of heterodimer plus mutagenesis validation, replicated across archaea","pmids":["18929577"],"is_preprint":false},{"year":2008,"finding":"Pyrococcus furiosus RPP21 adopts a structure consisting of two alpha-helices and a zinc-binding motif; NMR chemical shift perturbation showed that the primary contact surface of RPP21 with RPP29 is localized to its two helices.","method":"Solution NMR structure determination; NMR chemical shift perturbation","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 — NMR structure with direct mapping of protein-protein interaction surface","pmids":["18922021"],"is_preprint":false},{"year":2009,"finding":"Solution NMR structure of the Pyrococcus furiosus RPP21-RPP29 binary complex showed that complex formation is accompanied by coupled protein folding; enzymatic footprinting localized the RPP21-RPP29 pair to the specificity domain (S-domain) of the RNase P RNA, defining its functional domain of action.","method":"Solution NMR structure of binary complex; enzymatic footprinting of RPR","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 — NMR structure of complex plus enzymatic footprinting localizing it to RPR S-domain, multiple orthogonal methods","pmids":["19733182"],"is_preprint":false},{"year":2010,"finding":"Functional chimeric RNase P RNA experiments demonstrated that PhoRpp21 and PhoRpp29 (archaeal homologs of Rpp21 and Rpp29) function in the stabilization/activation of the S-domain of the RNase P RNA, while PhoRpp30 and PhoPop5 function in the C-domain, defining the domain-specific roles of these protein pairs.","method":"Chimeric RNase P RNA assays with domain-swapped RNAs; in vitro cleavage assays","journal":"Bioscience, biotechnology, and biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 — functional chimeric RNA epistasis with defined domain readout, single lab","pmids":["20139629"],"is_preprint":false},{"year":2012,"finding":"Isothermal titration calorimetry of archaeal RPP21-RPP29 interaction revealed that coupled protein folding contributes significantly to the excess negative heat capacity change (ΔCp) upon complex formation; a folding-deficient RPP21 point mutant confirmed the role of binding-coupled folding, and the interaction showed strong ionic strength and pH dependence.","method":"Isothermal titration calorimetry (ITC) over ranges of temperature, ionic strength, pH, with folding-deficient mutant","journal":"Biochemistry","confidence":"Medium","confidence_rationale":"Tier 1 — rigorous thermodynamic characterization with mutagenesis, single lab","pmids":["22243443"],"is_preprint":false},{"year":2016,"finding":"Rpp29 is recruited to a histone H3.3/RNA complex at transcription sites and Rpp29 knockdown increases H3.3 chromatin incorporation, demonstrating that Rpp29 represses histone H3.3 nucleosome deposition; POP1 and Rpp21 are similarly recruited, suggesting a variant RNase P regulates H3.3 chromatin assembly.","method":"Live-cell imaging of H3.3 complex; Rpp29 siRNA knockdown with H3.3 chromatin incorporation assay; colocalization experiments","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 — KD with specific chromatin phenotype plus live-cell imaging, single lab","pmids":["26842893"],"is_preprint":false},{"year":2016,"finding":"Pull-down assay showed that PhoRpp21 binds directly to RNase P RNA (PhopRNA) and serves as the primary binding element, while PhoRpp29 alone has reduced affinity; mutational analysis identified Lys53, Lys54, Lys56 at the N-terminal helix of PhoRpp21 and the 10 C-terminal residues of PhoRpp29 as essential for PhopRNA activation; deletion of the loop linking P11-P12 helices in the PhopRNA S-domain impaired complex binding.","method":"Pull-down assay with recombinant proteins and RNA; mutational analysis of protein residues and RNA elements","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 — pull-down plus systematic mutagenesis of both protein and RNA, single lab","pmids":["27810361"],"is_preprint":false},{"year":2017,"finding":"Rpp29 and Rpp21 are rapidly recruited to laser-microirradiated DNA damage sites in a PARP1-dependent manner, bind poly ADP-ribose (PAR) moieties, and their depletion impairs homology-directed repair (HDR) of double-strand breaks without affecting NHEJ; depletion of H1 RNA diminishes their recruitment, and RNase P activity is augmented after DNA damage in a PARP1-dependent manner.","method":"Laser microirradiation with live-cell imaging; siRNA knockdown with HDR/NHEJ reporter assays; PAR binding assays; PARP1 inhibitor experiments","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal methods (live imaging, functional repair assays, PAR binding), single lab","pmids":["28432356"],"is_preprint":false},{"year":2018,"finding":"Rpp29 interacts with histone H3.3 through a sequence element in its own N-terminus (absent in archaeal Rpp29), and with histone H2B at an adjacent site; Rpp29 represses H3.3 incorporation into transcriptionally active genes, represses mRNA and antisense RNA expression, and promotes heterochromatic PTMs (H3K9me3, H3K27me3) while repressing euchromatic PTMs; oncogenic H3.3 mutations alter the H3.3-Rpp29 interaction.","method":"Biochemical binding assay with recombinant proteins; Rpp29 KD in KNS42 glioma cells with chromatin incorporation, RNA expression, and histone PTM readouts; mutational analysis","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 — biochemical interaction mapping plus KD with multiple defined chromatin phenotypes, single lab","pmids":["29921582"],"is_preprint":false}],"current_model":"Rpp29/Pop4 is a core protein subunit of the ribonucleoprotein enzyme RNase P that adopts an OB-fold beta-barrel structure; it functions as a heterodimer with Rpp21 (via coupled folding upon binding) localized to the specificity domain (S-domain) of the RNase P RNA to activate pre-tRNA cleavage, while in mammals Rpp29 has acquired additional eukaryote-specific roles including repression of histone H3.3 nucleosome deposition (through direct interaction with H3.3 via its N-terminal extension) and PARP1-dependent recruitment to DNA damage sites to facilitate homology-directed repair."},"narrative":{"teleology":[{"year":1999,"claim":"Establishing Rpp29 as a bona fide subunit of the active human RNase P holoenzyme resolved its identity as a functional component of this essential tRNA-processing ribonucleoprotein.","evidence":"Immunoprecipitation of catalytically active RNase P from HeLa cells using anti-Rpp29 antibodies","pmids":["10024167"],"confidence":"Medium","gaps":["Single-lab immunoprecipitation without reciprocal validation from Rpp29 side","Stoichiometry and direct RNA contacts not determined","No functional assay of Rpp29 depletion on tRNA processing"]},{"year":2003,"claim":"Determination of the three-dimensional structure of archaeal Rpp29 as an OB-fold beta-barrel, combined with in vitro reconstitution showing its essentiality, provided the first structural framework for understanding how this subunit contributes to RNase P function.","evidence":"NMR structure determination of Mth Rpp29; reconstitution of archaeal RNase P holoenzyme; NMR chemical shift perturbation mapping RNA-binding surface","pmids":["14673079","14622001"],"confidence":"High","gaps":["RNA-binding interface mapped at low resolution via chemical shift perturbation","Eukaryotic Rpp29 structure not yet determined"]},{"year":2004,"claim":"A high-resolution crystal structure identified two candidate RNA-binding sites on the Rpp29 OB-fold and revealed that strand β7 mediates intermolecular protein–protein contacts, delineating separate interaction surfaces for RNA and protein partners.","evidence":"X-ray crystallography of Ph1771p at 2.0 Å resolution","pmids":["15317976"],"confidence":"High","gaps":["Functional validation of identified RNA-binding sites by mutagenesis not yet performed","Protein–protein interaction via β7 not confirmed in holoenzyme context"]},{"year":2008,"claim":"Crystal and NMR structures of the Rpp21–Rpp29 heterodimer revealed the molecular interface (Rpp21 N-terminal helices contacting Rpp29 N-terminal extension, β2, and C-terminal helix) and mutagenesis confirmed that heterodimerization is required for RNase P function.","evidence":"Crystal structure of PhoRpp21–PhoRpp29 complex; NMR structure of Pfu RPP21 with chemical shift perturbation mapping; mutational analysis","pmids":["18929577","18922021"],"confidence":"High","gaps":["Whether the same interface is preserved in the eukaryotic heterodimer","How the heterodimer contacts the RNA in the assembled holoenzyme"]},{"year":2009,"claim":"NMR structure of the RPP21–RPP29 binary complex demonstrated that complex formation involves coupled protein folding, and enzymatic footprinting localized the pair to the S-domain of RNase P RNA, defining its site of action within the holoenzyme.","evidence":"Solution NMR of binary complex; enzymatic footprinting of RNase P RNA","pmids":["19733182"],"confidence":"High","gaps":["Coupled folding characterized only in archaeal system","Precise nucleotide contacts within the S-domain not resolved"]},{"year":2010,"claim":"Chimeric RNA experiments functionally confirmed that the Rpp21–Rpp29 pair specifically stabilizes and activates the S-domain of RNase P RNA, distinguishing its role from the Pop5–Rpp30 pair that acts on the catalytic domain.","evidence":"Domain-swapped chimeric RNase P RNA cleavage assays in vitro","pmids":["20139629"],"confidence":"Medium","gaps":["Chimeric approach performed only with archaeal components","Mechanism of S-domain activation (conformational change vs. substrate positioning) unknown"]},{"year":2012,"claim":"Thermodynamic dissection of RPP21–RPP29 binding established that coupled folding contributes a large excess heat capacity change, providing a quantitative biophysical framework for the heterodimerization mechanism.","evidence":"ITC across temperature, ionic strength, and pH ranges with a folding-deficient RPP21 mutant","pmids":["22243443"],"confidence":"Medium","gaps":["Thermodynamic parameters measured only for archaeal proteins","How coupled folding is regulated in vivo not addressed"]},{"year":2016,"claim":"Discovery that Rpp29 is recruited to histone H3.3/RNA complexes at transcription sites and that its depletion increases H3.3 chromatin incorporation revealed an unexpected eukaryote-specific role for an RNase P subunit in chromatin regulation, distinct from tRNA processing.","evidence":"Live-cell imaging; siRNA knockdown with H3.3 chromatin incorporation assay in mammalian cells; pull-down and mutagenesis of archaeal Rpp21–Rpp29–RNA ternary complex","pmids":["26842893","27810361"],"confidence":"Medium","gaps":["Whether H3.3 repression requires intact RNase P catalytic activity","Mechanism by which Rpp29 prevents H3.3 deposition not defined","Single-lab observation for chromatin function"]},{"year":2017,"claim":"Demonstration that Rpp29 is recruited to DNA damage sites in a PARP1-dependent manner, binds PAR, and is required specifically for homology-directed repair established a second non-canonical function for this RNase P subunit in genome maintenance.","evidence":"Laser microirradiation with live-cell imaging; siRNA knockdown with HDR/NHEJ reporter assays; PAR binding assays; PARP inhibitor experiments","pmids":["28432356"],"confidence":"Medium","gaps":["Molecular mechanism linking Rpp29/PAR binding to HDR promotion unknown","Whether RNase P catalytic activity is required at damage sites unclear","Single-lab finding not independently replicated"]},{"year":2018,"claim":"Mapping the Rpp29–H3.3 interaction to a eukaryote-specific N-terminal extension of Rpp29 and showing that Rpp29 depletion derepresses euchromatic marks while reducing heterochromatic marks provided a molecular basis for how an RNase P subunit acquired chromatin-regulatory function.","evidence":"Recombinant protein binding assays; Rpp29 knockdown in KNS42 glioma cells with chromatin incorporation, RNA expression, and histone PTM analysis; oncogenic H3.3 mutant interaction assays","pmids":["29921582"],"confidence":"Medium","gaps":["Whether Rpp29 acts directly on chromatin remodelers or through H3.3 sequestration","In vivo validation of N-terminal domain requirement not performed","Relevance to non-glioma cell types not tested"]},{"year":null,"claim":"How Rpp29's canonical RNase P function and its non-canonical roles in chromatin regulation and DNA repair are coordinated within the same cell, and whether these activities are mediated by distinct Rpp29 pools or require intact RNase P catalytic activity, remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structure of eukaryotic Rpp29 in the context of the human RNase P holoenzyme","Whether Rpp29's chromatin and DNA repair roles are RNase P RNA-dependent","No in vivo separation-of-function mutants distinguishing canonical from non-canonical roles"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[1,2,3,10]},{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[9,12]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[4,6,7]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[9,11,12]},{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[9,12]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[0,1,7]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[11]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[9,12]}],"complexes":["RNase P","RNase MRP"],"partners":["RPP21","POP1","H3F3A","H2BC1","PARP1"],"other_free_text":[]},"mechanistic_narrative":"POP4 (Rpp29) is a core protein subunit of the RNase P and RNase MRP ribonucleoprotein complexes that functions in tRNA processing and has acquired additional eukaryote-specific roles in chromatin regulation and DNA repair. Rpp29 adopts an OB-fold beta-barrel structure and heterodimerizes with Rpp21 through a coupled-folding mechanism; this binary complex binds the specificity domain (S-domain) of the RNase P RNA to activate pre-tRNA cleavage [PMID:14673079, PMID:19733182, PMID:18929577]. In mammalian cells, Rpp29 directly interacts with histone H3.3 via a eukaryote-specific N-terminal extension and represses H3.3 nucleosome deposition at transcriptionally active genes, promoting heterochromatic histone modifications [PMID:26842893, PMID:29921582]. Rpp29 is also recruited to DNA damage sites in a PARP1-dependent manner, binds poly(ADP-ribose), and facilitates homology-directed repair of double-strand breaks [PMID:28432356]."},"prefetch_data":{"uniprot":{"accession":"O95707","full_name":"Ribonuclease P protein subunit p29","aliases":[],"length_aa":220,"mass_kda":25.4,"function":"Component of ribonuclease P, a ribonucleoprotein complex that generates mature tRNA molecules by cleaving their 5'-ends","subcellular_location":"Nucleus, nucleolus","url":"https://www.uniprot.org/uniprotkb/O95707/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/POP4","classification":"Common Essential","n_dependent_lines":1053,"n_total_lines":1208,"dependency_fraction":0.8716887417218543},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"RPP30","stoichiometry":4.0},{"gene":"DRG1","stoichiometry":0.2},{"gene":"NPM1","stoichiometry":0.2},{"gene":"SSB","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/POP4","total_profiled":1310},"omim":[{"mim_id":"606114","title":"POP4 HOMOLOG, RIBONUCLEASE P/MRP SUBUNIT; POP4","url":"https://www.omim.org/entry/606114"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Nucleoli","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/POP4"},"hgnc":{"alias_symbol":["RPP29"],"prev_symbol":[]},"alphafold":{"accession":"O95707","domains":[{"cath_id":"-","chopping":"12-53","consensus_level":"medium","plddt":79.7598,"start":12,"end":53},{"cath_id":"2.30.30.210","chopping":"96-220","consensus_level":"high","plddt":87.6822,"start":96,"end":220}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O95707","model_url":"https://alphafold.ebi.ac.uk/files/AF-O95707-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O95707-F1-predicted_aligned_error_v6.png","plddt_mean":83.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=POP4","jax_strain_url":"https://www.jax.org/strain/search?query=POP4"},"sequence":{"accession":"O95707","fasta_url":"https://rest.uniprot.org/uniprotkb/O95707.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O95707/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O95707"}},"corpus_meta":[{"pmid":"10024167","id":"PMC_10024167","title":"Rpp14 and Rpp29, two protein subunits of human ribonuclease P.","date":"1999","source":"RNA (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/10024167","citation_count":48,"is_preprint":false},{"pmid":"14673079","id":"PMC_14673079","title":"Structure of Mth11/Mth Rpp29, an essential protein subunit of archaeal and eukaryotic RNase P.","date":"2003","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/14673079","citation_count":40,"is_preprint":false},{"pmid":"18929577","id":"PMC_18929577","title":"Structure of an archaeal homolog of the human protein complex Rpp21-Rpp29 that is a key core component for the assembly of active ribonuclease P.","date":"2008","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/18929577","citation_count":34,"is_preprint":false},{"pmid":"19733182","id":"PMC_19733182","title":"Solution structure of an archaeal RNase P binary protein complex: formation of the 30-kDa complex between Pyrococcus furiosus RPP21 and RPP29 is accompanied by coupled protein folding and highlights critical features for protein-protein and protein-RNA interactions.","date":"2009","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/19733182","citation_count":34,"is_preprint":false},{"pmid":"15317976","id":"PMC_15317976","title":"Crystal structure of archaeal ribonuclease P protein Ph1771p from Pyrococcus horikoshii OT3: an archaeal homolog of eukaryotic ribonuclease P protein Rpp29.","date":"2004","source":"RNA (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/15317976","citation_count":32,"is_preprint":false},{"pmid":"14622001","id":"PMC_14622001","title":"NMR structure of an archaeal homologue of ribonuclease P protein Rpp29.","date":"2003","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/14622001","citation_count":26,"is_preprint":false},{"pmid":"28432356","id":"PMC_28432356","title":"A role of human RNase P subunits, Rpp29 and Rpp21, in homology directed-repair of double-strand breaks.","date":"2017","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/28432356","citation_count":25,"is_preprint":false},{"pmid":"26842893","id":"PMC_26842893","title":"RNase P protein subunit Rpp29 represses histone H3.3 nucleosome deposition.","date":"2016","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/26842893","citation_count":24,"is_preprint":false},{"pmid":"18922021","id":"PMC_18922021","title":"Solution structure of Pyrococcus furiosus RPP21, a component of the archaeal RNase P holoenzyme, and interactions with its RPP29 protein partner.","date":"2008","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18922021","citation_count":19,"is_preprint":false},{"pmid":"20139629","id":"PMC_20139629","title":"Archaeal homologs of human RNase P protein pairs Pop5 with Rpp30 and Rpp21 with Rpp29 work on distinct functional domains of the RNA subunit.","date":"2010","source":"Bioscience, biotechnology, and biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/20139629","citation_count":18,"is_preprint":false},{"pmid":"29921582","id":"PMC_29921582","title":"Rpp29 regulates histone H3.3 chromatin assembly through transcriptional mechanisms.","date":"2018","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/29921582","citation_count":16,"is_preprint":false},{"pmid":"15351636","id":"PMC_15351636","title":"Inhibition of the expression of the human RNase P protein subunits Rpp21, Rpp25, Rpp29 by external guide sequences (EGSs) and siRNA.","date":"2004","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/15351636","citation_count":16,"is_preprint":false},{"pmid":"22243443","id":"PMC_22243443","title":"Thermodynamics of coupled folding in the interaction of archaeal RNase P proteins RPP21 and RPP29.","date":"2012","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22243443","citation_count":9,"is_preprint":false},{"pmid":"12699688","id":"PMC_12699688","title":"Preparation of uniformly labeled NMR samples in Escherichia coli under the tight control of the araBAD promoter: expression of an archaeal homolog of the RNase P Rpp29 protein.","date":"2003","source":"Protein expression and purification","url":"https://pubmed.ncbi.nlm.nih.gov/12699688","citation_count":8,"is_preprint":false},{"pmid":"27810361","id":"PMC_27810361","title":"Functional characterization of archaeal homologs of human nuclear RNase P proteins Rpp21 and Rpp29 provides insights into the molecular basis of their cooperativity in catalysis.","date":"2016","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/27810361","citation_count":2,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.10.30.621158","title":"In a model of parasite-mediated exhaustion, stem-like CD8 T cells differentiate into an unconventional intermediate effector memory subset","date":"2024-11-03","source":"bioRxiv","url":"https://doi.org/10.1101/2024.10.30.621158","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8906,"output_tokens":3179,"usd":0.037201},"stage2":{"model":"claude-opus-4-6","input_tokens":6548,"output_tokens":2742,"usd":0.151935},"total_usd":0.189136,"stage1_batch_id":"msgbatch_01SUR8NDzVrNmyszWyJeCct7","stage2_batch_id":"msgbatch_01G7Yfutko3cDWzejrwH5AMx","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1999,\n      \"finding\": \"Rpp29 (human homolog of yeast Pop4p) is a protein subunit of human RNase P; antibodies against recombinant Rpp29 precipitate catalytically active RNase P from HeLa cells, establishing it as part of the active enzyme complex.\",\n      \"method\": \"Immunoprecipitation of catalytically active RNase P with polyclonal antibodies against recombinant Rpp29\",\n      \"journal\": \"RNA (New York, N.Y.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal immunoprecipitation of active enzyme, single lab\",\n      \"pmids\": [\"10024167\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"The archaeal Rpp29 homolog (Mth Rpp29/Mth11) adopts an oligonucleotide/oligosaccharide binding (OB) fold with a beta-barrel core and flexible N- and C-terminal extensions; it is an essential protein component of the archaeal RNase P holoenzyme as shown by reconstitution experiments, and NMR chemical shift perturbation identified its RNA-binding interface with the full RNase P RNA subunit.\",\n      \"method\": \"Solution NMR structure determination; reconstitution of archaeal RNase P holoenzyme from recombinant components; NMR chemical shift perturbation with full RNA subunit\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — NMR structure plus in vitro reconstitution demonstrating essentiality, multiple orthogonal methods\",\n      \"pmids\": [\"14673079\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"The archaeal Rpp29 homolog from Archaeoglobus fulgidus forms a six-stranded antiparallel beta-sheet structure with flexible N- and C-terminal tails; conserved surface residues in loop regions (beta2-beta3, beta4-beta5) and the flexible tails are likely RNA- and protein-interaction surfaces, consistent with the structural homology to Pop4p.\",\n      \"method\": \"Multidimensional NMR structure determination; amide proton exchange and 15N relaxation rate measurements\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — NMR structure with dynamics data, single lab\",\n      \"pmids\": [\"14622001\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Crystal structure of the archaeal Rpp29 homolog Ph1771p at 2.0 Å resolution revealed an OB-fold beta-barrel with two potential RNA-binding sites: a concave surface with clustered positive charges and a loop region (beta2-beta3) with conserved hydrophilic residues that interact with sulfate ion; strand beta7 mediates protein-protein interactions via intermolecular antiparallel beta-sheet contacts.\",\n      \"method\": \"X-ray crystallography at 2.0 Å resolution; structural comparison\",\n      \"journal\": \"RNA (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — high-resolution crystal structure with structural analysis of interaction surfaces\",\n      \"pmids\": [\"15317976\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"The archaeal homologs of Rpp21 and Rpp29 (PhoRpp21 and PhoRpp29) form a heterodimer whose crystal structure shows that the two N-terminal helices of PhoRpp21 interact with the N-terminal extension, beta-strand beta2, and C-terminal helix of PhoRpp29 via hydrogen bonds and salt bridges; mutational analysis confirmed that heterodimerization is important for RNase P function, and the complex displays a positively charged RNA-binding surface.\",\n      \"method\": \"Crystal structure determination of PhoRpp21-PhoRpp29 complex; mutational analysis of interface residues\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure of heterodimer plus mutagenesis validation, replicated across archaea\",\n      \"pmids\": [\"18929577\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Pyrococcus furiosus RPP21 adopts a structure consisting of two alpha-helices and a zinc-binding motif; NMR chemical shift perturbation showed that the primary contact surface of RPP21 with RPP29 is localized to its two helices.\",\n      \"method\": \"Solution NMR structure determination; NMR chemical shift perturbation\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — NMR structure with direct mapping of protein-protein interaction surface\",\n      \"pmids\": [\"18922021\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Solution NMR structure of the Pyrococcus furiosus RPP21-RPP29 binary complex showed that complex formation is accompanied by coupled protein folding; enzymatic footprinting localized the RPP21-RPP29 pair to the specificity domain (S-domain) of the RNase P RNA, defining its functional domain of action.\",\n      \"method\": \"Solution NMR structure of binary complex; enzymatic footprinting of RPR\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — NMR structure of complex plus enzymatic footprinting localizing it to RPR S-domain, multiple orthogonal methods\",\n      \"pmids\": [\"19733182\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Functional chimeric RNase P RNA experiments demonstrated that PhoRpp21 and PhoRpp29 (archaeal homologs of Rpp21 and Rpp29) function in the stabilization/activation of the S-domain of the RNase P RNA, while PhoRpp30 and PhoPop5 function in the C-domain, defining the domain-specific roles of these protein pairs.\",\n      \"method\": \"Chimeric RNase P RNA assays with domain-swapped RNAs; in vitro cleavage assays\",\n      \"journal\": \"Bioscience, biotechnology, and biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional chimeric RNA epistasis with defined domain readout, single lab\",\n      \"pmids\": [\"20139629\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Isothermal titration calorimetry of archaeal RPP21-RPP29 interaction revealed that coupled protein folding contributes significantly to the excess negative heat capacity change (ΔCp) upon complex formation; a folding-deficient RPP21 point mutant confirmed the role of binding-coupled folding, and the interaction showed strong ionic strength and pH dependence.\",\n      \"method\": \"Isothermal titration calorimetry (ITC) over ranges of temperature, ionic strength, pH, with folding-deficient mutant\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — rigorous thermodynamic characterization with mutagenesis, single lab\",\n      \"pmids\": [\"22243443\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Rpp29 is recruited to a histone H3.3/RNA complex at transcription sites and Rpp29 knockdown increases H3.3 chromatin incorporation, demonstrating that Rpp29 represses histone H3.3 nucleosome deposition; POP1 and Rpp21 are similarly recruited, suggesting a variant RNase P regulates H3.3 chromatin assembly.\",\n      \"method\": \"Live-cell imaging of H3.3 complex; Rpp29 siRNA knockdown with H3.3 chromatin incorporation assay; colocalization experiments\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KD with specific chromatin phenotype plus live-cell imaging, single lab\",\n      \"pmids\": [\"26842893\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Pull-down assay showed that PhoRpp21 binds directly to RNase P RNA (PhopRNA) and serves as the primary binding element, while PhoRpp29 alone has reduced affinity; mutational analysis identified Lys53, Lys54, Lys56 at the N-terminal helix of PhoRpp21 and the 10 C-terminal residues of PhoRpp29 as essential for PhopRNA activation; deletion of the loop linking P11-P12 helices in the PhopRNA S-domain impaired complex binding.\",\n      \"method\": \"Pull-down assay with recombinant proteins and RNA; mutational analysis of protein residues and RNA elements\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — pull-down plus systematic mutagenesis of both protein and RNA, single lab\",\n      \"pmids\": [\"27810361\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Rpp29 and Rpp21 are rapidly recruited to laser-microirradiated DNA damage sites in a PARP1-dependent manner, bind poly ADP-ribose (PAR) moieties, and their depletion impairs homology-directed repair (HDR) of double-strand breaks without affecting NHEJ; depletion of H1 RNA diminishes their recruitment, and RNase P activity is augmented after DNA damage in a PARP1-dependent manner.\",\n      \"method\": \"Laser microirradiation with live-cell imaging; siRNA knockdown with HDR/NHEJ reporter assays; PAR binding assays; PARP1 inhibitor experiments\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (live imaging, functional repair assays, PAR binding), single lab\",\n      \"pmids\": [\"28432356\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Rpp29 interacts with histone H3.3 through a sequence element in its own N-terminus (absent in archaeal Rpp29), and with histone H2B at an adjacent site; Rpp29 represses H3.3 incorporation into transcriptionally active genes, represses mRNA and antisense RNA expression, and promotes heterochromatic PTMs (H3K9me3, H3K27me3) while repressing euchromatic PTMs; oncogenic H3.3 mutations alter the H3.3-Rpp29 interaction.\",\n      \"method\": \"Biochemical binding assay with recombinant proteins; Rpp29 KD in KNS42 glioma cells with chromatin incorporation, RNA expression, and histone PTM readouts; mutational analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — biochemical interaction mapping plus KD with multiple defined chromatin phenotypes, single lab\",\n      \"pmids\": [\"29921582\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"Rpp29/Pop4 is a core protein subunit of the ribonucleoprotein enzyme RNase P that adopts an OB-fold beta-barrel structure; it functions as a heterodimer with Rpp21 (via coupled folding upon binding) localized to the specificity domain (S-domain) of the RNase P RNA to activate pre-tRNA cleavage, while in mammals Rpp29 has acquired additional eukaryote-specific roles including repression of histone H3.3 nucleosome deposition (through direct interaction with H3.3 via its N-terminal extension) and PARP1-dependent recruitment to DNA damage sites to facilitate homology-directed repair.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"POP4 (Rpp29) is a core protein subunit of the RNase P and RNase MRP ribonucleoprotein complexes that functions in tRNA processing and has acquired additional eukaryote-specific roles in chromatin regulation and DNA repair. Rpp29 adopts an OB-fold beta-barrel structure and heterodimerizes with Rpp21 through a coupled-folding mechanism; this binary complex binds the specificity domain (S-domain) of the RNase P RNA to activate pre-tRNA cleavage [PMID:14673079, PMID:19733182, PMID:18929577]. In mammalian cells, Rpp29 directly interacts with histone H3.3 via a eukaryote-specific N-terminal extension and represses H3.3 nucleosome deposition at transcriptionally active genes, promoting heterochromatic histone modifications [PMID:26842893, PMID:29921582]. Rpp29 is also recruited to DNA damage sites in a PARP1-dependent manner, binds poly(ADP-ribose), and facilitates homology-directed repair of double-strand breaks [PMID:28432356].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Establishing Rpp29 as a bona fide subunit of the active human RNase P holoenzyme resolved its identity as a functional component of this essential tRNA-processing ribonucleoprotein.\",\n      \"evidence\": \"Immunoprecipitation of catalytically active RNase P from HeLa cells using anti-Rpp29 antibodies\",\n      \"pmids\": [\"10024167\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab immunoprecipitation without reciprocal validation from Rpp29 side\", \"Stoichiometry and direct RNA contacts not determined\", \"No functional assay of Rpp29 depletion on tRNA processing\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Determination of the three-dimensional structure of archaeal Rpp29 as an OB-fold beta-barrel, combined with in vitro reconstitution showing its essentiality, provided the first structural framework for understanding how this subunit contributes to RNase P function.\",\n      \"evidence\": \"NMR structure determination of Mth Rpp29; reconstitution of archaeal RNase P holoenzyme; NMR chemical shift perturbation mapping RNA-binding surface\",\n      \"pmids\": [\"14673079\", \"14622001\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"RNA-binding interface mapped at low resolution via chemical shift perturbation\", \"Eukaryotic Rpp29 structure not yet determined\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"A high-resolution crystal structure identified two candidate RNA-binding sites on the Rpp29 OB-fold and revealed that strand β7 mediates intermolecular protein–protein contacts, delineating separate interaction surfaces for RNA and protein partners.\",\n      \"evidence\": \"X-ray crystallography of Ph1771p at 2.0 Å resolution\",\n      \"pmids\": [\"15317976\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional validation of identified RNA-binding sites by mutagenesis not yet performed\", \"Protein–protein interaction via β7 not confirmed in holoenzyme context\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Crystal and NMR structures of the Rpp21–Rpp29 heterodimer revealed the molecular interface (Rpp21 N-terminal helices contacting Rpp29 N-terminal extension, β2, and C-terminal helix) and mutagenesis confirmed that heterodimerization is required for RNase P function.\",\n      \"evidence\": \"Crystal structure of PhoRpp21–PhoRpp29 complex; NMR structure of Pfu RPP21 with chemical shift perturbation mapping; mutational analysis\",\n      \"pmids\": [\"18929577\", \"18922021\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the same interface is preserved in the eukaryotic heterodimer\", \"How the heterodimer contacts the RNA in the assembled holoenzyme\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"NMR structure of the RPP21–RPP29 binary complex demonstrated that complex formation involves coupled protein folding, and enzymatic footprinting localized the pair to the S-domain of RNase P RNA, defining its site of action within the holoenzyme.\",\n      \"evidence\": \"Solution NMR of binary complex; enzymatic footprinting of RNase P RNA\",\n      \"pmids\": [\"19733182\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Coupled folding characterized only in archaeal system\", \"Precise nucleotide contacts within the S-domain not resolved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Chimeric RNA experiments functionally confirmed that the Rpp21–Rpp29 pair specifically stabilizes and activates the S-domain of RNase P RNA, distinguishing its role from the Pop5–Rpp30 pair that acts on the catalytic domain.\",\n      \"evidence\": \"Domain-swapped chimeric RNase P RNA cleavage assays in vitro\",\n      \"pmids\": [\"20139629\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Chimeric approach performed only with archaeal components\", \"Mechanism of S-domain activation (conformational change vs. substrate positioning) unknown\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Thermodynamic dissection of RPP21–RPP29 binding established that coupled folding contributes a large excess heat capacity change, providing a quantitative biophysical framework for the heterodimerization mechanism.\",\n      \"evidence\": \"ITC across temperature, ionic strength, and pH ranges with a folding-deficient RPP21 mutant\",\n      \"pmids\": [\"22243443\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Thermodynamic parameters measured only for archaeal proteins\", \"How coupled folding is regulated in vivo not addressed\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Discovery that Rpp29 is recruited to histone H3.3/RNA complexes at transcription sites and that its depletion increases H3.3 chromatin incorporation revealed an unexpected eukaryote-specific role for an RNase P subunit in chromatin regulation, distinct from tRNA processing.\",\n      \"evidence\": \"Live-cell imaging; siRNA knockdown with H3.3 chromatin incorporation assay in mammalian cells; pull-down and mutagenesis of archaeal Rpp21–Rpp29–RNA ternary complex\",\n      \"pmids\": [\"26842893\", \"27810361\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether H3.3 repression requires intact RNase P catalytic activity\", \"Mechanism by which Rpp29 prevents H3.3 deposition not defined\", \"Single-lab observation for chromatin function\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstration that Rpp29 is recruited to DNA damage sites in a PARP1-dependent manner, binds PAR, and is required specifically for homology-directed repair established a second non-canonical function for this RNase P subunit in genome maintenance.\",\n      \"evidence\": \"Laser microirradiation with live-cell imaging; siRNA knockdown with HDR/NHEJ reporter assays; PAR binding assays; PARP inhibitor experiments\",\n      \"pmids\": [\"28432356\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular mechanism linking Rpp29/PAR binding to HDR promotion unknown\", \"Whether RNase P catalytic activity is required at damage sites unclear\", \"Single-lab finding not independently replicated\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Mapping the Rpp29–H3.3 interaction to a eukaryote-specific N-terminal extension of Rpp29 and showing that Rpp29 depletion derepresses euchromatic marks while reducing heterochromatic marks provided a molecular basis for how an RNase P subunit acquired chromatin-regulatory function.\",\n      \"evidence\": \"Recombinant protein binding assays; Rpp29 knockdown in KNS42 glioma cells with chromatin incorporation, RNA expression, and histone PTM analysis; oncogenic H3.3 mutant interaction assays\",\n      \"pmids\": [\"29921582\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether Rpp29 acts directly on chromatin remodelers or through H3.3 sequestration\", \"In vivo validation of N-terminal domain requirement not performed\", \"Relevance to non-glioma cell types not tested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How Rpp29's canonical RNase P function and its non-canonical roles in chromatin regulation and DNA repair are coordinated within the same cell, and whether these activities are mediated by distinct Rpp29 pools or require intact RNase P catalytic activity, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structure of eukaryotic Rpp29 in the context of the human RNase P holoenzyme\", \"Whether Rpp29's chromatin and DNA repair roles are RNase P RNA-dependent\", \"No in vivo separation-of-function mutants distinguishing canonical from non-canonical roles\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [1, 2, 3, 10]},\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [9, 12]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [4, 6, 7]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [9, 11, 12]},\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [9, 12]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [0, 1, 7]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [11]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [9, 12]}\n    ],\n    \"complexes\": [\n      \"RNase P\",\n      \"RNase MRP\"\n    ],\n    \"partners\": [\n      \"RPP21\",\n      \"POP1\",\n      \"H3F3A\",\n      \"H2BC1\",\n      \"PARP1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}