{"gene":"PF3D7_1333000","run_date":"2026-09-08T19:44:17","timeline":{"discoveries":[{"year":2005,"finding":"CPN20 (PF3D7_1333000) was shown by transfection experiments using fluorescent reporters to localize specifically to the apicoplast (plastid) of P. falciparum, establishing that the apicoplast has its own distinct type I chaperonin system comprising CPN20 and one of the two Cpn60 paralogs.","method":"Transfection with fluorescent reporter constructs; subcellular localization imaging","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct fluorescent reporter localization experiment in P. falciparum, single lab, single method with clear functional inference","pmids":["15926202"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"finding":"Recombinant CPN20 (PF3D7_1333000) functions as a bona fide co-chaperonin: it assists GroEL-mediated protein folding in vitro and can fully complement an E. coli GroES depletion at both normal and heat-shock temperatures. Structural characterization by circular dichroism and analytical ultracentrifugation confirmed the protein adopts the expected fold. The protein encodes two tandem Cpn10 domains.","method":"In vitro co-chaperonin activity assay with purified recombinant protein and GroEL; E. coli GroES complementation (genetic rescue); circular dichroism; analytical ultracentrifugation","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 1 / Moderate — reconstituted in vitro activity assay plus in vivo genetic complementation plus structural analysis, multiple orthogonal methods in a single rigorous study","pmids":["23326533"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"finding":"A cryo-EM study of the chloroplast Clp complex (cited within the paper) found that CPN20 co-chaperonin forms a cap on ClpP and represses ClpP proteolytic activity in vitro; however, structural predictions in P. falciparum failed to fit any of the three apicoplast-predicted CPN20-like proteins into a stable interaction model with either PfClpP or CPN60, leaving the question of whether Plasmodium CPN20 similarly caps ClpP unresolved and requiring future experimental work.","method":"Computational structural modelling (negative result for Plasmodium CPN20–ClpP interaction)","journal":"PLoS pathogens","confidence":"Low","confidence_rationale":"Tier 4 / Weak — computational modelling only, result is explicitly negative/unresolved; no experimental interaction demonstrated for CPN20 in Plasmodium","pmids":["40694565"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"CPN20 (PF3D7_1333000) is a 20 kDa apicoplast-resident co-chaperonin of P. falciparum that contains two tandem Cpn10 domains; it localizes specifically to the apicoplast (established by fluorescent reporter transfection), where it pairs with the apicoplast-targeted Cpn60 to form a distinct type I chaperonin system, and has been shown by in vitro reconstitution and bacterial genetic complementation to be fully functional as a co-chaperonin capable of supporting GroEL-mediated protein folding."},"narrative":{"mechanistic_narrative":"CPN20 (PF3D7_1333000) is an apicoplast-resident co-chaperonin of Plasmodium falciparum that constitutes, together with an apicoplast-targeted Cpn60 paralog, a distinct type I chaperonin system in the parasite's plastid [PMID:15926202]. Fluorescent reporter transfection established its specific localization to the apicoplast [PMID:15926202], and it encodes two tandem Cpn10 domains [PMID:23326533]. Recombinant CPN20 is a bona fide co-chaperonin: it assists GroEL-mediated protein folding in vitro, fully complements an E. coli GroES depletion at both normal and heat-shock temperatures, and adopts the expected fold as confirmed by circular dichroism and analytical ultracentrifugation [PMID:23326533]. Beyond its role as a functional co-chaperonin partnered with Cpn60, no additional interactions or substrates have been established in the available corpus; a computational effort to model an interaction between Plasmodium CPN20-like proteins and PfClpP or CPN60 was explicitly unresolved [PMID:40694565].","teleology":[{"year":2005,"claim":"Establishing where CPN20 acts answered whether the apicoplast maintains its own chaperonin machinery separate from other parasite compartments.","evidence":"Fluorescent reporter transfection and subcellular localization imaging in P. falciparum","pmids":["15926202"],"confidence":"Medium","gaps":["Localization inferred from reporter constructs rather than endogenous tagging","Which of the two Cpn60 paralogs pairs with CPN20 in vivo not directly demonstrated","No functional consequence of apicoplast targeting shown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2013,"claim":"Demonstrating co-chaperonin activity answered whether CPN20, despite its unusual tandem-domain architecture, is a functionally competent Cpn10-type co-chaperonin.","evidence":"In vitro GroEL-assisted folding assay with purified recombinant protein, E. coli GroES complementation (genetic rescue), circular dichroism and analytical ultracentrifugation","pmids":["23326533"],"confidence":"High","gaps":["Activity shown with bacterial GroEL rather than the native apicoplast Cpn60","No endogenous substrates of the apicoplast CPN20/Cpn60 system identified","In vivo essentiality in P. falciparum not addressed"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"claim":"A structural modelling effort tested whether Plasmodium CPN20 might cap and regulate ClpP protease as its chloroplast counterpart does, but the interaction could not be modelled.","evidence":"Computational structural modelling (negative result for Plasmodium CPN20–ClpP interaction)","pmids":["40694565"],"confidence":"Low","gaps":["Computational modelling only; no experimental CPN20–ClpP or CPN20–CPN60 interaction demonstrated in Plasmodium","Which of the apicoplast-predicted CPN20-like proteins is PF3D7_1333000 not resolved","Whether CPN20 regulates apicoplast proteolysis remains untested"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"Whether CPN20 partners the apicoplast Cpn60 in vivo, what endogenous substrates the system folds, and whether CPN20 has any role in apicoplast ClpP regulation remain unestablished.","evidence":"","pmids":[],"confidence":"Low","gaps":["No native CPN20/Cpn60 substrate identified","No experimental CPN20–ClpP interaction data","No loss-of-function/essentiality data in P. falciparum"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["Apicoplast type I chaperonin system (CPN20 co-chaperonin with apicoplast Cpn60) [#0]"],"partners":["CPN60 (APICOPLAST-TARGETED PARALOG) [#0]","GROEL (HETEROLOGOUS, IN VITRO CO-CHAPERONIN ACTIVITY) [#1]"],"other_free_text":["Contains two tandem Cpn10 domains [#1]","Fully complements E. coli GroES depletion at normal and heat-shock temperatures [#1]","Computational modelling could not fit Plasmodium CPN20-like proteins into a stable interaction with PfClpP or CPN60 [#2]"]}},"prefetch_data":{},"corpus_meta":[{"pmid":"15926202","id":"PMC_15926202","title":"Organelle-specific cochaperonins in apicomplexan parasites.","date":"2005","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/15926202","citation_count":22,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfCPN20"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"23326533","id":"PMC_23326533","title":"P. falciparum cpn20 is a bona fide co-chaperonin that can replace GroES in E. coli.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23326533","citation_count":9,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["CPN20","PfCPN20"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"40694565","id":"","title":"A chaperonin complex regulates organelle proteostasis in malaria parasites.","date":"2025","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/40694565","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["CPN20"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"32975363","id":"","title":"An apicoplast-resident folate transporter is essential for sporogony of malaria parasites.","date":"2020","source":"Cellular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/32975363","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["CPN20"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"32310999","id":"","title":"Insights into the intracellular localization, protein associations and artemisinin resistance properties of Plasmodium falciparum K13.","date":"2020","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/32310999","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["CPN20"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"22503086","id":"","title":"Transcript level responses of Plasmodium falciparum to antimycin A.","date":"2012","source":"Protist","url":"https://pubmed.ncbi.nlm.nih.gov/22503086","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["CPN20"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"31775392","id":"","title":"Small Molecule Inhibitors Targeting the Heat Shock Protein System of Human Obligate Protozoan Parasites.","date":"2019","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/31775392","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["CPN20"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"24850912","id":"","title":"Reduced ribosomes of the apicoplast and mitochondrion of Plasmodium spp. and predicted interactions with antibiotics.","date":"2014","source":"Open biology","url":"https://pubmed.ncbi.nlm.nih.gov/24850912","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["CPN20"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"21380560","id":"","title":"The apicomplexan plastid and its evolution.","date":"2011","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/21380560","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["CPN20"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":11221,"output_tokens":1010,"usd":0.024407,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":5758,"output_tokens":1965,"usd":0.038957,"stage2_stop_reason":"end_turn"},"total_usd":0.063364,"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\": 2005,\n      \"finding\": \"CPN20 (PF3D7_1333000) was shown by transfection experiments using fluorescent reporters to localize specifically to the apicoplast (plastid) of P. falciparum, establishing that the apicoplast has its own distinct type I chaperonin system comprising CPN20 and one of the two Cpn60 paralogs.\",\n      \"method\": \"Transfection with fluorescent reporter constructs; subcellular localization imaging\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct fluorescent reporter localization experiment in P. falciparum, single lab, single method with clear functional inference\",\n      \"pmids\": [\"15926202\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Recombinant CPN20 (PF3D7_1333000) functions as a bona fide co-chaperonin: it assists GroEL-mediated protein folding in vitro and can fully complement an E. coli GroES depletion at both normal and heat-shock temperatures. Structural characterization by circular dichroism and analytical ultracentrifugation confirmed the protein adopts the expected fold. The protein encodes two tandem Cpn10 domains.\",\n      \"method\": \"In vitro co-chaperonin activity assay with purified recombinant protein and GroEL; E. coli GroES complementation (genetic rescue); circular dichroism; analytical ultracentrifugation\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — reconstituted in vitro activity assay plus in vivo genetic complementation plus structural analysis, multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"23326533\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"A cryo-EM study of the chloroplast Clp complex (cited within the paper) found that CPN20 co-chaperonin forms a cap on ClpP and represses ClpP proteolytic activity in vitro; however, structural predictions in P. falciparum failed to fit any of the three apicoplast-predicted CPN20-like proteins into a stable interaction model with either PfClpP or CPN60, leaving the question of whether Plasmodium CPN20 similarly caps ClpP unresolved and requiring future experimental work.\",\n      \"method\": \"Computational structural modelling (negative result for Plasmodium CPN20–ClpP interaction)\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — computational modelling only, result is explicitly negative/unresolved; no experimental interaction demonstrated for CPN20 in Plasmodium\",\n      \"pmids\": [\"40694565\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"CPN20 (PF3D7_1333000) is a 20 kDa apicoplast-resident co-chaperonin of P. falciparum that contains two tandem Cpn10 domains; it localizes specifically to the apicoplast (established by fluorescent reporter transfection), where it pairs with the apicoplast-targeted Cpn60 to form a distinct type I chaperonin system, and has been shown by in vitro reconstitution and bacterial genetic complementation to be fully functional as a co-chaperonin capable of supporting GroEL-mediated protein folding.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CPN20 (PF3D7_1333000) is an apicoplast-resident co-chaperonin of Plasmodium falciparum that constitutes, together with an apicoplast-targeted Cpn60 paralog, a distinct type I chaperonin system in the parasite's plastid [#0]. Fluorescent reporter transfection established its specific localization to the apicoplast [#0], and it encodes two tandem Cpn10 domains [#1]. Recombinant CPN20 is a bona fide co-chaperonin: it assists GroEL-mediated protein folding in vitro, fully complements an E. coli GroES depletion at both normal and heat-shock temperatures, and adopts the expected fold as confirmed by circular dichroism and analytical ultracentrifugation [#1]. Beyond its role as a functional co-chaperonin partnered with Cpn60, no additional interactions or substrates have been established in the available corpus; a computational effort to model an interaction between Plasmodium CPN20-like proteins and PfClpP or CPN60 was explicitly unresolved [#2].\",\n  \"teleology\": [\n    {\n      \"year\": 2005,\n      \"claim\": \"Establishing where CPN20 acts answered whether the apicoplast maintains its own chaperonin machinery separate from other parasite compartments.\",\n      \"evidence\": \"Fluorescent reporter transfection and subcellular localization imaging in P. falciparum\",\n      \"pmids\": [\"15926202\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Localization inferred from reporter constructs rather than endogenous tagging\",\n        \"Which of the two Cpn60 paralogs pairs with CPN20 in vivo not directly demonstrated\",\n        \"No functional consequence of apicoplast targeting shown\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstrating co-chaperonin activity answered whether CPN20, despite its unusual tandem-domain architecture, is a functionally competent Cpn10-type co-chaperonin.\",\n      \"evidence\": \"In vitro GroEL-assisted folding assay with purified recombinant protein, E. coli GroES complementation (genetic rescue), circular dichroism and analytical ultracentrifugation\",\n      \"pmids\": [\"23326533\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Activity shown with bacterial GroEL rather than the native apicoplast Cpn60\",\n        \"No endogenous substrates of the apicoplast CPN20/Cpn60 system identified\",\n        \"In vivo essentiality in P. falciparum not addressed\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"A structural modelling effort tested whether Plasmodium CPN20 might cap and regulate ClpP protease as its chloroplast counterpart does, but the interaction could not be modelled.\",\n      \"evidence\": \"Computational structural modelling (negative result for Plasmodium CPN20\\u2013ClpP interaction)\",\n      \"pmids\": [\"40694565\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Computational modelling only; no experimental CPN20\\u2013ClpP or CPN20\\u2013CPN60 interaction demonstrated in Plasmodium\",\n        \"Which of the apicoplast-predicted CPN20-like proteins is PF3D7_1333000 not resolved\",\n        \"Whether CPN20 regulates apicoplast proteolysis remains untested\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether CPN20 partners the apicoplast Cpn60 in vivo, what endogenous substrates the system folds, and whether CPN20 has any role in apicoplast ClpP regulation remain unestablished.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No native CPN20/Cpn60 substrate identified\",\n        \"No experimental CPN20\\u2013ClpP interaction data\",\n        \"No loss-of-function/essentiality data in P. falciparum\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0051087\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0006457\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020011\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0061077\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"complexes\": [\n      \"Apicoplast type I chaperonin system (CPN20 co-chaperonin with apicoplast Cpn60) [#0]\"\n    ],\n    \"partners\": [\n      \"Cpn60 (apicoplast-targeted paralog) [#0]\",\n      \"GroEL (heterologous, in vitro co-chaperonin activity) [#1]\"\n    ],\n    \"other_free_text\": [\n      \"Contains two tandem Cpn10 domains [#1]\",\n      \"Fully complements E. coli GroES depletion at normal and heat-shock temperatures [#1]\",\n      \"Computational modelling could not fit Plasmodium CPN20-like proteins into a stable interaction with PfClpP or CPN60 [#2]\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1333000","name":null,"product":"20 kDa chaperonin","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_1347800","name":null,"product":"20 kDa chaperonin, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_1267600","name":null,"product":"20 kDa chaperonin, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"CPN20","evaluation":null}