{"gene":"PF3D7_0420400","run_date":"2026-09-08T19:44:17","timeline":{"discoveries":[{"year":2013,"finding":"PF3D7_0420400 (PfRRF2) is targeted to the mitochondrion of P. falciparum, as established by localization of its leader sequence fused to GFP.","method":"Leader sequence-GFP fusion localization assay","journal":"Molecular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct subcellular localization via GFP fusion, single lab, single method","pmids":["23614815"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"finding":"PF3D7_0420400 (PfRRF2) additionally localizes in the cytoplasm beyond its mitochondrial targeting, suggesting adjunct cytoplasmic functions.","method":"Leader sequence-GFP fusion localization assay","journal":"Molecular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct localization experiment, single lab, single method, functional implication inferred but not directly tested","pmids":["23614815"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"finding":"PF3D7_0420400 (PfRRF2) forms homodimers stabilized by disulfide interaction(s), a property not previously reported for any characterized ribosome recycling factor.","method":"Biochemical analysis of recombinant protein (dimer/disulfide characterization)","journal":"Molecular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — biochemical characterization of recombinant protein, single lab, single method","pmids":["23614815"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"finding":"Recombinant PF3D7_0420400 (PfRRF2) binds E. coli ribosomes and can split monosomes in the presence of the relevant mitochondrial EF-G, demonstrating ribosome-recycling activity.","method":"In vitro ribosome-binding and monosome-splitting assay with recombinant protein","journal":"Molecular microbiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution of enzymatic (recycling) activity with recombinant protein and defined cofactor, single lab but two orthogonal biochemical readouts (binding and splitting)","pmids":["23614815"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"finding":"PF3D7_0420400 (PfRRF2) failed to complement the E. coli LJ14frr(ts) RRF temperature-sensitive mutant, indicating it cannot fully substitute for bacterial RRF in vivo despite retaining ribosome-splitting activity in vitro.","method":"Complementation assay in E. coli LJ14frr(ts) mutant","journal":"Molecular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — genetic complementation assay, single lab, negative result mechanistically informative","pmids":["23614815"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"finding":"Monosome splitting by mitochondrial IF3 (PfIF3a) was enhanced by PF3D7_0420400 (PfRRF2) together with mitochondrial EF-G, placing PfRRF2 as a functional partner of PfIF3a in mitochondrial ribosome recycling/anti-association.","method":"In vitro monosome-splitting assay with recombinant proteins","journal":"Molecular microbiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution assay with defined recombinant components, single lab, direct functional interaction demonstrated","pmids":["25689481"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"PF3D7_0420400 (RRF2) is a mitochondrion-targeted (and additionally cytoplasm-localizing) ribosome-recycling factor in P. falciparum that forms disulfide-linked homodimers, binds ribosomes, splits monosomes in vitro in cooperation with the mitochondrial elongation factor EF-G, and functionally enhances mitochondrial IF3a-mediated ribosome anti-association activity, thereby participating in organellar translation recycling; it cannot complement bacterial RRF in vivo despite retaining in vitro recycling activity."},"narrative":{"mechanistic_narrative":"PF3D7_0420400 (RRF2) is a ribosome-recycling factor of Plasmodium falciparum that participates in organellar (mitochondrial) translation by disassembling post-termination ribosomes [PMID:23614815]. Its leader sequence directs it to the mitochondrion, with an additional cytoplasmic pool [PMID:23614815]. Recombinant RRF2 binds ribosomes and splits monosomes in vitro, an activity dependent on the mitochondrial elongation factor EF-G [PMID:23614815], and it enhances the monosome-splitting/anti-association activity of the mitochondrial initiation factor IF3a (PfIF3a) when acting together with EF-G, marking RRF2 as a functional partner in mitochondrial ribosome recycling [PMID:25689481]. Distinctive among characterized recycling factors, RRF2 forms disulfide-stabilized homodimers [PMID:23614815]. Despite retaining in vitro splitting activity, RRF2 does not complement a bacterial RRF temperature-sensitive mutant in vivo, indicating it cannot fully substitute for bacterial RRF [PMID:23614815]. Beyond these biochemical and localization findings, no in vivo functional or structural characterization of RRF2 has been established in the available corpus.","teleology":[{"year":2013,"claim":"It was unknown where a candidate P. falciparum recycling factor acts in the cell; localization established RRF2 as a mitochondrion-targeted protein with an additional cytoplasmic pool, defining its organellar context.","evidence":"Leader sequence-GFP fusion localization assay in P. falciparum","pmids":["23614815"],"confidence":"Medium","gaps":["Localization inferred from a leader-GFP fusion rather than endogenous tagging","Functional role of the cytoplasmic pool not tested","Native full-length protein localization not confirmed"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"claim":"Whether RRF2 possessed the biochemical hallmarks of a recycling factor was unknown; recombinant protein was shown to bind ribosomes and split monosomes in the presence of mitochondrial EF-G, demonstrating bona fide recycling activity and its dependence on EF-G.","evidence":"In vitro ribosome-binding and monosome-splitting assay with recombinant protein and E. coli ribosomes","pmids":["23614815"],"confidence":"High","gaps":["Splitting demonstrated on heterologous E. coli ribosomes rather than native mitochondrial ribosomes","In vivo requirement for the activity not established","No structural basis for the activity"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"claim":"The oligomeric state of RRF2 was uncharacterized; biochemical analysis revealed disulfide-stabilized homodimers, a feature not previously reported for any characterized recycling factor.","evidence":"Biochemical dimer/disulfide characterization of recombinant protein","pmids":["23614815"],"confidence":"Medium","gaps":["Functional consequence of dimerization for recycling activity not tested","Whether dimerization occurs in vivo not shown","Redox regulation of the disulfide not explored"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"claim":"It was unclear whether RRF2 is functionally equivalent to bacterial RRF; failure to complement an E. coli RRF temperature-sensitive mutant showed it cannot fully substitute in vivo despite in vitro activity.","evidence":"Genetic complementation assay in E. coli LJ14frr(ts) mutant","pmids":["23614815"],"confidence":"Medium","gaps":["Molecular basis for the complementation failure not identified","Does not address RRF2 function in its native P. falciparum mitochondrion"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"claim":"How RRF2 integrates with other mitochondrial translation factors was open; reconstitution showed RRF2 with EF-G enhances PfIF3a-mediated monosome splitting, placing RRF2 as a functional partner of IF3a in mitochondrial ribosome recycling/anti-association.","evidence":"In vitro monosome-splitting assay with recombinant PfIF3a, EF-G and RRF2","pmids":["25689481"],"confidence":"High","gaps":["Interaction demonstrated in vitro with recombinant components, not in cells","Stoichiometry and direct physical contact between RRF2 and IF3a not defined","Native mitochondrial ribosome substrate not used"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"The in vivo role, essentiality, and structural mechanism of RRF2 in P. falciparum mitochondrial translation remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No genetic knockout/knockdown phenotype in P. falciparum","No structure of RRF2 or its complexes with EF-G/IF3a/ribosome","Direct binding to native mitochondrial ribosomes not demonstrated"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["MITOCHONDRIAL EF-G (ELONGATION FACTOR G) — COFACTOR FOR RRF2 MONOSOME SPLITTING [#3, #5]","PFIF3A (MITOCHONDRIAL INITIATION FACTOR 3) — ACTIVITY ENHANCED BY RRF2 WITH EF-G [#5]"],"other_free_text":["Forms disulfide-stabilized homodimers, a feature not previously reported for characterized ribosome recycling factors [#2]","Cannot complement the E. coli LJ14frr(ts) RRF mutant in vivo despite retaining in vitro splitting activity [#4]"]}},"prefetch_data":{},"corpus_meta":[{"pmid":"25689481","id":"PMC_25689481","title":"Targeting and function of proteins mediating translation initiation in organelles of Plasmodium falciparum.","date":"2015","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/25689481","citation_count":14,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ribosome-recycling factor","PfRRF2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"23614815","id":"PMC_23614815","title":"Recycling factors for ribosome disassembly in the apicoplast and mitochondrion of Plasmodium falciparum.","date":"2013","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/23614815","citation_count":11,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfRRF2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"36750737","id":"","title":"Population genetic analysis of Plasmodium knowlesi reveals differential selection and exchange events between Borneo and Peninsular sub-populations.","date":"2023","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/36750737","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["RRF2"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":5245,"output_tokens":1429,"usd":0.018585,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":6364,"output_tokens":2540,"usd":0.04766,"stage2_stop_reason":"end_turn"},"total_usd":0.066245,"stage1_batch_id":"msgbatch_01SRp5hyRc82zNjddxyCCXGk","stage2_batch_id":"msgbatch_01K3BTmBazRo3pRrMvyaPMTY","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2013,\n      \"finding\": \"PF3D7_0420400 (PfRRF2) is targeted to the mitochondrion of P. falciparum, as established by localization of its leader sequence fused to GFP.\",\n      \"method\": \"Leader sequence-GFP fusion localization assay\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct subcellular localization via GFP fusion, single lab, single method\",\n      \"pmids\": [\"23614815\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PF3D7_0420400 (PfRRF2) additionally localizes in the cytoplasm beyond its mitochondrial targeting, suggesting adjunct cytoplasmic functions.\",\n      \"method\": \"Leader sequence-GFP fusion localization assay\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct localization experiment, single lab, single method, functional implication inferred but not directly tested\",\n      \"pmids\": [\"23614815\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PF3D7_0420400 (PfRRF2) forms homodimers stabilized by disulfide interaction(s), a property not previously reported for any characterized ribosome recycling factor.\",\n      \"method\": \"Biochemical analysis of recombinant protein (dimer/disulfide characterization)\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — biochemical characterization of recombinant protein, single lab, single method\",\n      \"pmids\": [\"23614815\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Recombinant PF3D7_0420400 (PfRRF2) binds E. coli ribosomes and can split monosomes in the presence of the relevant mitochondrial EF-G, demonstrating ribosome-recycling activity.\",\n      \"method\": \"In vitro ribosome-binding and monosome-splitting assay with recombinant protein\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution of enzymatic (recycling) activity with recombinant protein and defined cofactor, single lab but two orthogonal biochemical readouts (binding and splitting)\",\n      \"pmids\": [\"23614815\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PF3D7_0420400 (PfRRF2) failed to complement the E. coli LJ14frr(ts) RRF temperature-sensitive mutant, indicating it cannot fully substitute for bacterial RRF in vivo despite retaining ribosome-splitting activity in vitro.\",\n      \"method\": \"Complementation assay in E. coli LJ14frr(ts) mutant\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — genetic complementation assay, single lab, negative result mechanistically informative\",\n      \"pmids\": [\"23614815\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Monosome splitting by mitochondrial IF3 (PfIF3a) was enhanced by PF3D7_0420400 (PfRRF2) together with mitochondrial EF-G, placing PfRRF2 as a functional partner of PfIF3a in mitochondrial ribosome recycling/anti-association.\",\n      \"method\": \"In vitro monosome-splitting assay with recombinant proteins\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution assay with defined recombinant components, single lab, direct functional interaction demonstrated\",\n      \"pmids\": [\"25689481\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"PF3D7_0420400 (RRF2) is a mitochondrion-targeted (and additionally cytoplasm-localizing) ribosome-recycling factor in P. falciparum that forms disulfide-linked homodimers, binds ribosomes, splits monosomes in vitro in cooperation with the mitochondrial elongation factor EF-G, and functionally enhances mitochondrial IF3a-mediated ribosome anti-association activity, thereby participating in organellar translation recycling; it cannot complement bacterial RRF in vivo despite retaining in vitro recycling activity.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PF3D7_0420400 (RRF2) is a ribosome-recycling factor of Plasmodium falciparum that participates in organellar (mitochondrial) translation by disassembling post-termination ribosomes [#0, #3]. Its leader sequence directs it to the mitochondrion, with an additional cytoplasmic pool [#0, #1]. Recombinant RRF2 binds ribosomes and splits monosomes in vitro, an activity dependent on the mitochondrial elongation factor EF-G [#3], and it enhances the monosome-splitting/anti-association activity of the mitochondrial initiation factor IF3a (PfIF3a) when acting together with EF-G, marking RRF2 as a functional partner in mitochondrial ribosome recycling [#5]. Distinctive among characterized recycling factors, RRF2 forms disulfide-stabilized homodimers [#2]. Despite retaining in vitro splitting activity, RRF2 does not complement a bacterial RRF temperature-sensitive mutant in vivo, indicating it cannot fully substitute for bacterial RRF [#4]. Beyond these biochemical and localization findings, no in vivo functional or structural characterization of RRF2 has been established in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2013,\n      \"claim\": \"It was unknown where a candidate P. falciparum recycling factor acts in the cell; localization established RRF2 as a mitochondrion-targeted protein with an additional cytoplasmic pool, defining its organellar context.\",\n      \"evidence\": \"Leader sequence-GFP fusion localization assay in P. falciparum\",\n      \"pmids\": [\"23614815\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Localization inferred from a leader-GFP fusion rather than endogenous tagging\", \"Functional role of the cytoplasmic pool not tested\", \"Native full-length protein localization not confirmed\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Whether RRF2 possessed the biochemical hallmarks of a recycling factor was unknown; recombinant protein was shown to bind ribosomes and split monosomes in the presence of mitochondrial EF-G, demonstrating bona fide recycling activity and its dependence on EF-G.\",\n      \"evidence\": \"In vitro ribosome-binding and monosome-splitting assay with recombinant protein and E. coli ribosomes\",\n      \"pmids\": [\"23614815\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Splitting demonstrated on heterologous E. coli ribosomes rather than native mitochondrial ribosomes\", \"In vivo requirement for the activity not established\", \"No structural basis for the activity\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"The oligomeric state of RRF2 was uncharacterized; biochemical analysis revealed disulfide-stabilized homodimers, a feature not previously reported for any characterized recycling factor.\",\n      \"evidence\": \"Biochemical dimer/disulfide characterization of recombinant protein\",\n      \"pmids\": [\"23614815\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of dimerization for recycling activity not tested\", \"Whether dimerization occurs in vivo not shown\", \"Redox regulation of the disulfide not explored\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"It was unclear whether RRF2 is functionally equivalent to bacterial RRF; failure to complement an E. coli RRF temperature-sensitive mutant showed it cannot fully substitute in vivo despite in vitro activity.\",\n      \"evidence\": \"Genetic complementation assay in E. coli LJ14frr(ts) mutant\",\n      \"pmids\": [\"23614815\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis for the complementation failure not identified\", \"Does not address RRF2 function in its native P. falciparum mitochondrion\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"How RRF2 integrates with other mitochondrial translation factors was open; reconstitution showed RRF2 with EF-G enhances PfIF3a-mediated monosome splitting, placing RRF2 as a functional partner of IF3a in mitochondrial ribosome recycling/anti-association.\",\n      \"evidence\": \"In vitro monosome-splitting assay with recombinant PfIF3a, EF-G and RRF2\",\n      \"pmids\": [\"25689481\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Interaction demonstrated in vitro with recombinant components, not in cells\", \"Stoichiometry and direct physical contact between RRF2 and IF3a not defined\", \"Native mitochondrial ribosome substrate not used\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The in vivo role, essentiality, and structural mechanism of RRF2 in P. falciparum mitochondrial translation remain unresolved.\",\n      \"evidence\": null,\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No genetic knockout/knockdown phenotype in P. falciparum\", \"No structure of RRF2 or its complexes with EF-G/IF3a/ribosome\", \"Direct binding to native mitochondrial ribosomes not demonstrated\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0043022\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"GO:0006415\", \"supporting_discovery_ids\": [3, 5]},\n      {\"term_id\": \"GO:0042803\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005737\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0032790\", \"supporting_discovery_ids\": [3, 5]},\n      {\"term_id\": \"GO:0032543\", \"supporting_discovery_ids\": [0, 5]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"Mitochondrial EF-G (elongation factor G) — cofactor for RRF2 monosome splitting [#3, #5]\",\n      \"PfIF3a (mitochondrial initiation factor 3) — activity enhanced by RRF2 with EF-G [#5]\"\n    ],\n    \"other_free_text\": [\n      \"Forms disulfide-stabilized homodimers, a feature not previously reported for characterized ribosome recycling factors [#2]\",\n      \"Cannot complement the E. coli LJ14frr(ts) RRF mutant in vivo despite retaining in vitro splitting activity [#4]\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_0420400","name":null,"product":"ribosome-recycling factor","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_0521800","name":null,"product":"ribosome-recycling factor, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0513200","name":null,"product":"ribosome-recycling factor, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"RRF2","evaluation":null}