{"gene":"PF3D7_0802200","run_date":"2026-09-08T12:51:27","timeline":{"discoveries":[{"year":2000,"finding":"1-CysPxn (Pf1-Cys-Prx) was molecularly cloned from P. falciparum and characterized as a peroxiredoxin family member, establishing its identity as a distinct peroxidase gene in the parasite.","method":"Molecular cloning and biochemical characterization","journal":"Molecular and biochemical parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — molecular cloning and initial characterization in a single study; no full abstract text available to assess orthogonal methods","pmids":["10960175"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2005,"finding":"1-CysPxn (Pf1-Cys-Prx) is localized to the cytoplasm of P. falciparum and shows stage-specific elevated expression during trophozoite and early schizont stages, coinciding with peak heme-digestion activity, suggesting a role in detoxifying metabolism-derived ROS.","method":"Western blotting, confocal laser scanning microscopy, real-time quantitative RT-PCR","journal":"Parasitology international","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct localization by immunofluorescence confirmed by protein expression profiling; two orthogonal methods in a single lab","pmids":["15710548"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2005,"finding":"Recombinant 1-CysPxn (rPf1-Cys-Prx) binds directly to ferriprotoporphyrin IX (heme/FP) at physiological cytosolic pH (7.4), competes with glutathione (GSH) for FP, reduces GSH-mediated FP degradation (iron release reduced to 23% of control), protects glutamine synthetase and enolase from iron-derived ROS inactivation, and reduces membrane association of FP with red blood cell ghosts.","method":"In vitro binding assay (FP-agarose pulldown), mixed-function oxidation enzyme protection assay, spectrophotometric FP degradation assay, red blood cell ghost membrane association assay","journal":"The FEBS journal","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — multiple orthogonal in vitro functional assays with recombinant protein in a single study; direct biochemical demonstration of heme binding and protective activity","pmids":["15794764"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2003,"finding":"1-Cys Prx of P. yoelii is expressed in a stage-specific manner in the trophozoite cytoplasm during blood-stage infection and shows antioxidant activity protecting yeast enolase from inactivation by a mixed-function oxidation system, while 2-Cys Prx is expressed constitutively throughout the life cycle.","method":"Immunofluorescent antibody staining, confocal laser scanning microscopy, mixed-function oxidation enzyme protection assay with recombinant protein","journal":"International journal for parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization plus in vitro enzymatic protection assay with recombinant protein; two orthogonal methods, single lab, rodent malaria ortholog","pmids":["14572508"],"is_preprint":false,"attribution":[{"species":"Plasmodium yoelii","strain":""}]},{"year":2008,"finding":"Transcriptional regulation of pf1-cys-prx is controlled by a trophozoite/schizont stage-specific cis-acting enhancer in its 5' region that is bound by stage-specific DNA-binding proteins, and increased histone acetylation (including recruitment of PfGCN5 histone acetyltransferase) in the 5' region of pf1-cys-prx correlates with its transcriptional activity during trophozoite/schizont stages.","method":"Reporter assays, electrophoretic mobility shift assay (EMSA), DNase I footprinting, chromatin immunoprecipitation (ChIP)","journal":"Molecular and biochemical parasitology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (reporter assay, EMSA, footprinting, ChIP) in a single study establishing mechanistic basis of stage-specific transcription","pmids":["18692528"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"finding":"1-CysPxn (Pf1-Cys-Prx) is targeted to the cytoplasm of P. falciparum, as determined by systematic subcellular localization mapping; unlike some other redox proteins in Plasmodium, it does not utilize alternative-translation-initiation for dual targeting.","method":"Systematic fluorescence-based subcellular localization (GFP reporter/fractionation) as part of complete redox compartmentation mapping","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct localization experiment within a comprehensive study; single lab but part of a systematic mapping effort","pmids":["21203490"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"finding":"Knockout of 1-CysPxn (Pf1-Cys-Prx) in P. falciparum did not render parasites hypersensitive to reactive oxygen species, reactive nitrogen species, chloroquine, or heat stress, indicating that 1-CysPxn's cytoplasmic function is independent from that of PfTPx-1 (which does confer heat stress resistance).","method":"Genetic knockout (KO) of pf1-cys-prx, phenotypic assays for ROS, RNS, chloroquine, and heat stress sensitivity","journal":"Parasitology international","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — clean genetic KO with defined phenotypic readouts; single lab, single study; negative result mechanistically informative","pmids":["23201565"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"finding":"Recombinant 1-Cys Prx proteins from P. vivax (Pv1-Cys-Prx) and P. knowlesi (Pk1-Cys-Prx) exhibit antioxidant activity in the mixed-function oxidation assay and are localized to the parasite cytoplasm, consistent with the P. falciparum ortholog.","method":"Heterologous expression in E. coli, mixed-function oxidation assay, immunofluorescence with polyclonal antibodies","journal":"Experimental parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro enzymatic assay plus direct localization; two orthogonal methods, single lab, orthologous proteins in different Plasmodium species","pmids":["23178658"],"is_preprint":false,"attribution":[{"species":"Plasmodium vivax","strain":""},{"species":"Plasmodium knowlesi","strain":""}]},{"year":2013,"finding":"In P. berghei ookinetes, 1-Cys Prx expression is strongly upregulated in mosquito bloodmeal-derived ookinetes compared to culture-derived ookinetes, and is induced by exogenous ROS in a dose-dependent manner; in a TPx-1 knockout parasite line, 1-Cys Prx expression occurs significantly earlier and is detectable in cultured ookinetes (where it is normally absent), indicating that 1-Cys Prx partially compensates for the loss of TPx-1.","method":"Transcriptional profiling (qRT-PCR), confocal immunofluorescence imaging, genetic knockout of tpx-1 with comparison of 1-Cys Prx expression in TPx-1KO vs wild-type ookinetes","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal genetic approach (TPx-1 KO) combined with transcriptional and protein-level expression analysis using two orthogonal methods; single lab but multiple complementary experiments","pmids":["23382676"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]}],"current_model":"PF3D7_0802200 (1-CysPxn/Pf1-Cys-Prx) is a cytoplasmic peroxiredoxin in P. falciparum whose transcription is controlled by a stage-specific cis-enhancer bound by trophozoite/schizont-specific factors and regulated by PfGCN5-dependent histone acetylation; the recombinant protein directly binds heme (FP), competes with glutathione for FP, reduces iron-dependent ROS generation, and protects proteins from oxidative damage, while genetic knockout shows it is dispensable for resistance to ROS, RNS, chloroquine, and heat stress under standard conditions, with its cytoplasmic antioxidant function distinct from but partially overlapping with TPx-1 in ookinetes."},"narrative":{"mechanistic_narrative":"PF3D7_0802200 (1-CysPxn/Pf1-Cys-Prx) is a cytoplasmic peroxiredoxin of Plasmodium falciparum that functions in antioxidant defense against metabolism-derived reactive oxygen species during intraerythrocytic development [PMID:15710548, PMID:15794764, PMID:21203490]. Its protein expression is elevated during the trophozoite and early schizont stages, coinciding with the period of peak heme-digestion activity [PMID:15710548], and this stage-specificity is set transcriptionally by a trophozoite/schizont-specific cis-acting enhancer in the 5' region that is bound by stage-specific DNA-binding proteins, together with PfGCN5-dependent histone acetylation of the same region [PMID:18692528]. Biochemically, recombinant 1-CysPxn binds ferriprotoporphyrin IX (heme/FP) directly at cytosolic pH, competes with glutathione for FP, limits GSH-mediated FP degradation and the accompanying iron release, and protects target proteins such as glutamine synthetase and enolase from iron-derived oxidative inactivation [PMID:15794764]. Despite these in vitro protective activities, genetic knockout of the gene does not sensitize parasites to ROS, RNS, chloroquine, or heat stress under standard conditions, indicating that its cytoplasmic function is dispensable and distinct from the heat-stress-protective PfTPx-1 [PMID:23201565]. Orthologs in P. yoelii, P. vivax, and P. knowlesi share cytoplasmic localization and mixed-function-oxidation antioxidant activity [PMID:14572508, PMID:23178658], and in P. berghei ookinetes 1-Cys Prx is induced by ROS and expressed earlier upon loss of TPx-1, indicating partial functional compensation between the two peroxiredoxins [PMID:23382676].","teleology":[{"year":2000,"claim":"Establishing the molecular identity of the gene was the first step: cloning defined 1-CysPxn as a distinct peroxiredoxin-family peroxidase in P. falciparum rather than an uncharacterized ORF.","evidence":"Molecular cloning and biochemical characterization in P. falciparum","pmids":["10960175"],"confidence":"Medium","gaps":["No functional or localization data at this stage","Enzymatic substrate not defined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2003,"claim":"Work in the rodent malaria ortholog first tied a 1-Cys Prx to stage-specific trophozoite cytoplasmic expression and demonstrable antioxidant protection, framing the family's blood-stage role.","evidence":"Immunofluorescence and mixed-function oxidation enzyme-protection assay with recombinant P. yoelii protein","pmids":["14572508"],"confidence":"Medium","gaps":["Rodent ortholog, not PF3D7_0802200 directly","No in vivo requirement tested"],"attribution":[{"species":"Plasmodium yoelii","strain":""}]},{"year":2005,"claim":"Two 2005 studies resolved where and when the P. falciparum protein acts and what it does: cytoplasmic, trophozoite/schizont-elevated expression, plus direct heme binding, competition with GSH, and protection of proteins from iron-derived ROS.","evidence":"Western blot, confocal microscopy and qRT-PCR for expression [#1]; FP-agarose pulldown, FP-degradation and enzyme-protection assays with recombinant protein [#2]","pmids":["15710548","15794764"],"confidence":"High","gaps":["Peroxidase reaction cycle and redox partner not defined in vitro","In vivo relevance of heme binding untested"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2008,"claim":"The mechanistic basis of the observed stage-specific expression was defined: a 5' cis-enhancer bound by stage-specific factors plus PfGCN5-dependent histone acetylation drive trophozoite/schizont transcription.","evidence":"Reporter assays, EMSA, DNase I footprinting, and ChIP in P. falciparum","pmids":["18692528"],"confidence":"High","gaps":["Identity of the stage-specific DNA-binding factors not established","Link between transcriptional control and antioxidant demand not directly tested"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"claim":"Systematic redox-compartment mapping confirmed exclusive cytoplasmic targeting and showed the protein does not use alternative translation initiation for dual localization, unlike some other Plasmodium redox proteins.","evidence":"Fluorescence-based subcellular localization within a genome-scale redox mapping study in P. falciparum","pmids":["21203490"],"confidence":"Medium","gaps":["Does not address functional consequence of localization"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"claim":"Genetic knockout tested whether the biochemical antioxidant activity is physiologically required, showing the gene is dispensable for resistance to ROS, RNS, chloroquine, and heat stress and functionally distinct from PfTPx-1.","evidence":"Gene knockout and phenotypic stress-sensitivity assays in P. falciparum","pmids":["23201565"],"confidence":"Medium","gaps":["Redundancy with other peroxiredoxins under standard conditions not excluded","Phenotypes under non-standard or in vivo conditions untested"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2012,"claim":"Orthologs from P. vivax and P. knowlesi extended the cytoplasmic, mixed-function-oxidation antioxidant activity across human-infective Plasmodium species, indicating conservation.","evidence":"Heterologous expression, mixed-function oxidation assay, and immunofluorescence in P. vivax and P. knowlesi","pmids":["23178658"],"confidence":"Medium","gaps":["Ortholog data, not PF3D7_0802200 itself","No knockout in these species"],"attribution":[{"species":"Plasmodium vivax","strain":""},{"species":"Plasmodium knowlesi","strain":""}]},{"year":2013,"claim":"Reciprocal genetics in the P. berghei ookinete revealed functional interplay: 1-Cys Prx is ROS-inducible and is expressed earlier when TPx-1 is deleted, indicating partial compensation between the two peroxiredoxins.","evidence":"qRT-PCR, confocal immunofluorescence, and tpx-1 knockout comparison in P. berghei ookinetes","pmids":["23382676"],"confidence":"High","gaps":["Compensation shown at expression level, not by rescue of a knockout phenotype","Ookinete-stage finding; blood-stage compensation not tested"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":null,"claim":"The physiological substrate, redox cycling partner, and the condition under which 1-CysPxn's antioxidant/heme-binding activity becomes essential remain undefined.","evidence":"No timeline discovery identifies an in vivo essential context, reducing partner, or the fate of bound heme","pmids":[],"confidence":"Low","gaps":["No physiological reducing substrate/partner identified","Condition of non-redundancy unknown","Structural basis of heme binding not determined"],"attribution":[]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["FERRIPROTOPORPHYRIN IX / HEME (DIRECT BINDING, COMPETES WITH GSH) [#2]","GLUTATHIONE (COMPETES FOR FP) [#2]","PFGCN5 HISTONE ACETYLTRANSFERASE (RECRUITED TO PF1-CYS-PRX 5' REGION DURING TRANSCRIPTIONAL ACTIVATION) [#4]","PFTPX-1 (FUNCTIONALLY DISTINCT, PARTIALLY COMPENSATING PEROXIREDOXIN) [#6, #8]"],"other_free_text":["Stage-specific expression peaks in trophozoite/early schizont stages, coinciding with peak heme digestion [#1].","Transcription is controlled by a trophozoite/schizont-specific 5' cis-enhancer bound by stage-specific DNA-binding proteins [#4].","In vitro protects glutamine synthetase and enolase from iron-derived ROS inactivation and reduces FP membrane association with RBC ghosts [#2].","Knockout is dispensable for resistance to ROS, RNS, chloroquine, and heat stress under standard conditions [#6].","In P. berghei ookinetes, 1-Cys Prx is ROS-inducible and upregulated/earlier-expressed upon TPx-1 loss [#8].","Orthologs conserved as cytoplasmic antioxidant proteins in P. yoelii, P. vivax, and P. knowlesi [#3, #7]."]}},"prefetch_data":{},"corpus_meta":[{"pmid":"21203490","id":"PMC_21203490","title":"Compartmentation of redox metabolism in malaria parasites.","date":"2010","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/21203490","citation_count":122,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"16910770","id":"PMC_16910770","title":"Thioredoxin networks in the malarial parasite Plasmodium falciparum.","date":"2006","source":"Antioxidants & redox signaling","url":"https://pubmed.ncbi.nlm.nih.gov/16910770","citation_count":72,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["1-cys peroxiredoxin"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"15701514","id":"PMC_15701514","title":"Crystal structure of a novel Plasmodium falciparum 1-Cys peroxiredoxin.","date":"2005","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/15701514","citation_count":71,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["1-cys peroxiredoxin"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"10960175","id":"PMC_10960175","title":"Molecular cloning and characterization of a peroxiredoxin from the human malaria parasite Plasmodium falciparum.","date":"2000","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/10960175","citation_count":53,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"15710548","id":"PMC_15710548","title":"Expression of mRNAs and proteins for peroxiredoxins in Plasmodium falciparum erythrocytic stage.","date":"2005","source":"Parasitology international","url":"https://pubmed.ncbi.nlm.nih.gov/15710548","citation_count":47,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"11295184","id":"PMC_11295184","title":"Isolation and functional analysis of two thioredoxin peroxidases (peroxiredoxins) from Plasmodium falciparum.","date":"2001","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/11295184","citation_count":45,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"15794764","id":"PMC_15794764","title":"Roles of 1-Cys peroxiredoxin in haem detoxification in the human malaria parasite Plasmodium falciparum.","date":"2005","source":"The FEBS journal","url":"https://pubmed.ncbi.nlm.nih.gov/15794764","citation_count":28,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["1-cys peroxiredoxin"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"18084896","id":"PMC_18084896","title":"Peroxiredoxin systems of protozoal parasites.","date":"2007","source":"Sub-cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18084896","citation_count":27,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["1-cys peroxiredoxin"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"14572508","id":"PMC_14572508","title":"Expression profiles of peroxiredoxin proteins of the rodent malaria parasite Plasmodium yoelii.","date":"2003","source":"International journal for parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/14572508","citation_count":24,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["1-cys peroxiredoxin"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"23382676","id":"PMC_23382676","title":"Expression of cytosolic peroxiredoxins in Plasmodium berghei ookinetes is regulated by environmental factors in the mosquito bloodmeal.","date":"2013","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/23382676","citation_count":20,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["1-cys peroxiredoxin"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"23201565","id":"PMC_23201565","title":"2-Cys peroxiredoxin of Plasmodium falciparum is involved in resistance to heat stress of the parasite.","date":"2012","source":"Parasitology international","url":"https://pubmed.ncbi.nlm.nih.gov/23201565","citation_count":17,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"23178658","id":"PMC_23178658","title":"Plasmodium vivax and Plasmodium knowlesi: cloning, expression and functional analysis of 1-Cys peroxiredoxin.","date":"2012","source":"Experimental parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/23178658","citation_count":14,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["1-cys peroxiredoxin"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"18692528","id":"PMC_18692528","title":"5' sequence- and chromatin modification-dependent gene expression in Plasmodium falciparum erythrocytic stage.","date":"2008","source":"Molecular and biochemical parasitology","url":"https://pubmed.ncbi.nlm.nih.gov/18692528","citation_count":11,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"12144348","id":"PMC_12144348","title":"Homology modeling and docking mechanism of the mercaptosuccinate and methotrexate to P. falciparum 1-Cys peroxiredoxin: a preliminary molecular study.","date":"2002","source":"Journal of biomolecular structure & dynamics","url":"https://pubmed.ncbi.nlm.nih.gov/12144348","citation_count":9,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["1-cys peroxiredoxin"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"23874139","id":"PMC_23874139","title":"Development of Monoclonal Antibodies That Target 1-Cys Peroxiredoxin and Differentiate Plasmodium falciparum from P. vivax and P. knowlesi.","date":"2013","source":"Tropical medicine and health","url":"https://pubmed.ncbi.nlm.nih.gov/23874139","citation_count":7,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["1-cys peroxiredoxin"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"35481660","id":"PMC_35481660","title":"Characterization of the glutathione-dependent reduction of the peroxiredoxin 5 homolog PfAOP from Plasmodium falciparum.","date":"2022","source":"Protein science : a publication of the Protein Society","url":"https://pubmed.ncbi.nlm.nih.gov/35481660","citation_count":6,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["1-cys peroxiredoxin"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10159,"output_tokens":2905,"usd":0.037026,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8154,"output_tokens":3661,"usd":0.066147,"stage2_stop_reason":"end_turn"},"total_usd":0.103173,"stage1_batch_id":"msgbatch_01DisAaTypwmC8QwdMBuePHo","stage2_batch_id":"msgbatch_0184zxZTqxiEfdYYfPMfkqjb","note":"batch pricing = 50% of standard"},"stage1_raw":"I need to carefully distinguish PF3D7_0802200 (1-CysPxn, referred to in abstracts as \"Pf1-Cys-Prx\" or \"1-Cys Prx\") from the closely related but DISTINCT protein PfAOP (also called \"antioxidant protein\"), which is a SEPARATE gene (a 1-Cys mechanism Prx with homology to PrxV/atypical 2-Cys class). Papers [3] and [16] are explicitly about PfAOP, not PF3D7_0802200. I must not conflate them.\n\nLet me also note: Paper [2] discusses both but reports novel biochemical data on both AOP and the classic 1-Cys Prx. I'll extract only what applies to 1-CysPxn (PF3D7_0802200).\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2000,\n      \"finding\": \"1-CysPxn (Pf1-Cys-Prx) was molecularly cloned from P. falciparum and characterized as a peroxiredoxin family member, establishing its identity as a distinct peroxidase gene in the parasite.\",\n      \"method\": \"Molecular cloning and biochemical characterization\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — molecular cloning and initial characterization in a single study; no full abstract text available to assess orthogonal methods\",\n      \"pmids\": [\"10960175\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"1-CysPxn (Pf1-Cys-Prx) is localized to the cytoplasm of P. falciparum and shows stage-specific elevated expression during trophozoite and early schizont stages, coinciding with peak heme-digestion activity, suggesting a role in detoxifying metabolism-derived ROS.\",\n      \"method\": \"Western blotting, confocal laser scanning microscopy, real-time quantitative RT-PCR\",\n      \"journal\": \"Parasitology international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct localization by immunofluorescence confirmed by protein expression profiling; two orthogonal methods in a single lab\",\n      \"pmids\": [\"15710548\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Recombinant 1-CysPxn (rPf1-Cys-Prx) binds directly to ferriprotoporphyrin IX (heme/FP) at physiological cytosolic pH (7.4), competes with glutathione (GSH) for FP, reduces GSH-mediated FP degradation (iron release reduced to 23% of control), protects glutamine synthetase and enolase from iron-derived ROS inactivation, and reduces membrane association of FP with red blood cell ghosts.\",\n      \"method\": \"In vitro binding assay (FP-agarose pulldown), mixed-function oxidation enzyme protection assay, spectrophotometric FP degradation assay, red blood cell ghost membrane association assay\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — multiple orthogonal in vitro functional assays with recombinant protein in a single study; direct biochemical demonstration of heme binding and protective activity\",\n      \"pmids\": [\"15794764\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"1-Cys Prx of P. yoelii is expressed in a stage-specific manner in the trophozoite cytoplasm during blood-stage infection and shows antioxidant activity protecting yeast enolase from inactivation by a mixed-function oxidation system, while 2-Cys Prx is expressed constitutively throughout the life cycle.\",\n      \"method\": \"Immunofluorescent antibody staining, confocal laser scanning microscopy, mixed-function oxidation enzyme protection assay with recombinant protein\",\n      \"journal\": \"International journal for parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization plus in vitro enzymatic protection assay with recombinant protein; two orthogonal methods, single lab, rodent malaria ortholog\",\n      \"pmids\": [\"14572508\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Transcriptional regulation of pf1-cys-prx is controlled by a trophozoite/schizont stage-specific cis-acting enhancer in its 5' region that is bound by stage-specific DNA-binding proteins, and increased histone acetylation (including recruitment of PfGCN5 histone acetyltransferase) in the 5' region of pf1-cys-prx correlates with its transcriptional activity during trophozoite/schizont stages.\",\n      \"method\": \"Reporter assays, electrophoretic mobility shift assay (EMSA), DNase I footprinting, chromatin immunoprecipitation (ChIP)\",\n      \"journal\": \"Molecular and biochemical parasitology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (reporter assay, EMSA, footprinting, ChIP) in a single study establishing mechanistic basis of stage-specific transcription\",\n      \"pmids\": [\"18692528\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"1-CysPxn (Pf1-Cys-Prx) is targeted to the cytoplasm of P. falciparum, as determined by systematic subcellular localization mapping; unlike some other redox proteins in Plasmodium, it does not utilize alternative-translation-initiation for dual targeting.\",\n      \"method\": \"Systematic fluorescence-based subcellular localization (GFP reporter/fractionation) as part of complete redox compartmentation mapping\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct localization experiment within a comprehensive study; single lab but part of a systematic mapping effort\",\n      \"pmids\": [\"21203490\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Knockout of 1-CysPxn (Pf1-Cys-Prx) in P. falciparum did not render parasites hypersensitive to reactive oxygen species, reactive nitrogen species, chloroquine, or heat stress, indicating that 1-CysPxn's cytoplasmic function is independent from that of PfTPx-1 (which does confer heat stress resistance).\",\n      \"method\": \"Genetic knockout (KO) of pf1-cys-prx, phenotypic assays for ROS, RNS, chloroquine, and heat stress sensitivity\",\n      \"journal\": \"Parasitology international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — clean genetic KO with defined phenotypic readouts; single lab, single study; negative result mechanistically informative\",\n      \"pmids\": [\"23201565\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Recombinant 1-Cys Prx proteins from P. vivax (Pv1-Cys-Prx) and P. knowlesi (Pk1-Cys-Prx) exhibit antioxidant activity in the mixed-function oxidation assay and are localized to the parasite cytoplasm, consistent with the P. falciparum ortholog.\",\n      \"method\": \"Heterologous expression in E. coli, mixed-function oxidation assay, immunofluorescence with polyclonal antibodies\",\n      \"journal\": \"Experimental parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro enzymatic assay plus direct localization; two orthogonal methods, single lab, orthologous proteins in different Plasmodium species\",\n      \"pmids\": [\"23178658\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium vivax\", \"strain\": \"\"},\n        {\"species\": \"Plasmodium knowlesi\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"In P. berghei ookinetes, 1-Cys Prx expression is strongly upregulated in mosquito bloodmeal-derived ookinetes compared to culture-derived ookinetes, and is induced by exogenous ROS in a dose-dependent manner; in a TPx-1 knockout parasite line, 1-Cys Prx expression occurs significantly earlier and is detectable in cultured ookinetes (where it is normally absent), indicating that 1-Cys Prx partially compensates for the loss of TPx-1.\",\n      \"method\": \"Transcriptional profiling (qRT-PCR), confocal immunofluorescence imaging, genetic knockout of tpx-1 with comparison of 1-Cys Prx expression in TPx-1KO vs wild-type ookinetes\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal genetic approach (TPx-1 KO) combined with transcriptional and protein-level expression analysis using two orthogonal methods; single lab but multiple complementary experiments\",\n      \"pmids\": [\"23382676\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"PF3D7_0802200 (1-CysPxn/Pf1-Cys-Prx) is a cytoplasmic peroxiredoxin in P. falciparum whose transcription is controlled by a stage-specific cis-enhancer bound by trophozoite/schizont-specific factors and regulated by PfGCN5-dependent histone acetylation; the recombinant protein directly binds heme (FP), competes with glutathione for FP, reduces iron-dependent ROS generation, and protects proteins from oxidative damage, while genetic knockout shows it is dispensable for resistance to ROS, RNS, chloroquine, and heat stress under standard conditions, with its cytoplasmic antioxidant function distinct from but partially overlapping with TPx-1 in ookinetes.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PF3D7_0802200 (1-CysPxn/Pf1-Cys-Prx) is a cytoplasmic peroxiredoxin of Plasmodium falciparum that functions in antioxidant defense against metabolism-derived reactive oxygen species during intraerythrocytic development [#1, #2, #5]. Its protein expression is elevated during the trophozoite and early schizont stages, coinciding with the period of peak heme-digestion activity [#1], and this stage-specificity is set transcriptionally by a trophozoite/schizont-specific cis-acting enhancer in the 5' region that is bound by stage-specific DNA-binding proteins, together with PfGCN5-dependent histone acetylation of the same region [#4]. Biochemically, recombinant 1-CysPxn binds ferriprotoporphyrin IX (heme/FP) directly at cytosolic pH, competes with glutathione for FP, limits GSH-mediated FP degradation and the accompanying iron release, and protects target proteins such as glutamine synthetase and enolase from iron-derived oxidative inactivation [#2]. Despite these in vitro protective activities, genetic knockout of the gene does not sensitize parasites to ROS, RNS, chloroquine, or heat stress under standard conditions, indicating that its cytoplasmic function is dispensable and distinct from the heat-stress-protective PfTPx-1 [#6]. Orthologs in P. yoelii, P. vivax, and P. knowlesi share cytoplasmic localization and mixed-function-oxidation antioxidant activity [#3, #7], and in P. berghei ookinetes 1-Cys Prx is induced by ROS and expressed earlier upon loss of TPx-1, indicating partial functional compensation between the two peroxiredoxins [#8].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Establishing the molecular identity of the gene was the first step: cloning defined 1-CysPxn as a distinct peroxiredoxin-family peroxidase in P. falciparum rather than an uncharacterized ORF.\",\n      \"evidence\": \"Molecular cloning and biochemical characterization in P. falciparum\",\n      \"pmids\": [\"10960175\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional or localization data at this stage\", \"Enzymatic substrate not defined\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Work in the rodent malaria ortholog first tied a 1-Cys Prx to stage-specific trophozoite cytoplasmic expression and demonstrable antioxidant protection, framing the family's blood-stage role.\",\n      \"evidence\": \"Immunofluorescence and mixed-function oxidation enzyme-protection assay with recombinant P. yoelii protein\",\n      \"pmids\": [\"14572508\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Rodent ortholog, not PF3D7_0802200 directly\", \"No in vivo requirement tested\"],\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Two 2005 studies resolved where and when the P. falciparum protein acts and what it does: cytoplasmic, trophozoite/schizont-elevated expression, plus direct heme binding, competition with GSH, and protection of proteins from iron-derived ROS.\",\n      \"evidence\": \"Western blot, confocal microscopy and qRT-PCR for expression [#1]; FP-agarose pulldown, FP-degradation and enzyme-protection assays with recombinant protein [#2]\",\n      \"pmids\": [\"15710548\", \"15794764\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Peroxidase reaction cycle and redox partner not defined in vitro\", \"In vivo relevance of heme binding untested\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"The mechanistic basis of the observed stage-specific expression was defined: a 5' cis-enhancer bound by stage-specific factors plus PfGCN5-dependent histone acetylation drive trophozoite/schizont transcription.\",\n      \"evidence\": \"Reporter assays, EMSA, DNase I footprinting, and ChIP in P. falciparum\",\n      \"pmids\": [\"18692528\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the stage-specific DNA-binding factors not established\", \"Link between transcriptional control and antioxidant demand not directly tested\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Systematic redox-compartment mapping confirmed exclusive cytoplasmic targeting and showed the protein does not use alternative translation initiation for dual localization, unlike some other Plasmodium redox proteins.\",\n      \"evidence\": \"Fluorescence-based subcellular localization within a genome-scale redox mapping study in P. falciparum\",\n      \"pmids\": [\"21203490\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not address functional consequence of localization\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Genetic knockout tested whether the biochemical antioxidant activity is physiologically required, showing the gene is dispensable for resistance to ROS, RNS, chloroquine, and heat stress and functionally distinct from PfTPx-1.\",\n      \"evidence\": \"Gene knockout and phenotypic stress-sensitivity assays in P. falciparum\",\n      \"pmids\": [\"23201565\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Redundancy with other peroxiredoxins under standard conditions not excluded\", \"Phenotypes under non-standard or in vivo conditions untested\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Orthologs from P. vivax and P. knowlesi extended the cytoplasmic, mixed-function-oxidation antioxidant activity across human-infective Plasmodium species, indicating conservation.\",\n      \"evidence\": \"Heterologous expression, mixed-function oxidation assay, and immunofluorescence in P. vivax and P. knowlesi\",\n      \"pmids\": [\"23178658\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Ortholog data, not PF3D7_0802200 itself\", \"No knockout in these species\"],\n      \"attribution\": [{\"species\": \"Plasmodium vivax\", \"strain\": \"\"}, {\"species\": \"Plasmodium knowlesi\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Reciprocal genetics in the P. berghei ookinete revealed functional interplay: 1-Cys Prx is ROS-inducible and is expressed earlier when TPx-1 is deleted, indicating partial compensation between the two peroxiredoxins.\",\n      \"evidence\": \"qRT-PCR, confocal immunofluorescence, and tpx-1 knockout comparison in P. berghei ookinetes\",\n      \"pmids\": [\"23382676\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Compensation shown at expression level, not by rescue of a knockout phenotype\", \"Ookinete-stage finding; blood-stage compensation not tested\"],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The physiological substrate, redox cycling partner, and the condition under which 1-CysPxn's antioxidant/heme-binding activity becomes essential remain undefined.\",\n      \"evidence\": \"No timeline discovery identifies an in vivo essential context, reducing partner, or the fate of bound heme\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No physiological reducing substrate/partner identified\", \"Condition of non-redundancy unknown\", \"Structural basis of heme binding not determined\"],\n      \"attribution\": []\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0051920\", \"supporting_discovery_ids\": [0, 3, 7]},\n      {\"term_id\": \"GO:0004601\", \"supporting_discovery_ids\": [2, 3, 7]},\n      {\"term_id\": \"GO:0020037\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005737\", \"supporting_discovery_ids\": [1, 3, 5, 7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0006979\", \"supporting_discovery_ids\": [2, 3, 8]},\n      {\"term_id\": \"GO:0042744\", \"supporting_discovery_ids\": [2, 3]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"Ferriprotoporphyrin IX / heme (direct binding, competes with GSH) [#2]\",\n      \"Glutathione (competes for FP) [#2]\",\n      \"PfGCN5 histone acetyltransferase (recruited to pf1-cys-prx 5' region during transcriptional activation) [#4]\",\n      \"PfTPx-1 (functionally distinct, partially compensating peroxiredoxin) [#6, #8]\"\n    ],\n    \"other_free_text\": [\n      \"Stage-specific expression peaks in trophozoite/early schizont stages, coinciding with peak heme digestion [#1].\",\n      \"Transcription is controlled by a trophozoite/schizont-specific 5' cis-enhancer bound by stage-specific DNA-binding proteins [#4].\",\n      \"In vitro protects glutamine synthetase and enolase from iron-derived ROS inactivation and reduces FP membrane association with RBC ghosts [#2].\",\n      \"Knockout is dispensable for resistance to ROS, RNS, chloroquine, and heat stress under standard conditions [#6].\",\n      \"In P. berghei ookinetes, 1-Cys Prx is ROS-inducible and upregulated/earlier-expressed upon TPx-1 loss [#8].\",\n      \"Orthologs conserved as cytoplasmic antioxidant proteins in P. yoelii, P. vivax, and P. knowlesi [#3, #7].\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_0802200","name":null,"product":"1-cys peroxiredoxin","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_1228000","name":null,"product":"1-cys peroxiredoxin, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0116700","name":null,"product":"1-cys peroxiredoxin","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"","evaluation":null}