{"gene":"PF3D7_0104300","run_date":"2026-09-07T10:55:51","timeline":{"discoveries":[{"year":2007,"finding":"Two distinct mutations in the UBP1 gene (encoding a deubiquitinating enzyme) of Plasmodium chabaudi were independently selected under chloroquine (high concentration) or artesunate drug pressure, each mapping to a critical residue in a homologous human deubiquitinating protein structure, implicating UBP1 mutations in modulating parasite responses to chloroquine and artemisinin derivatives.","method":"Linkage Group Selection from genetic cross, sequencing, structural homology mapping","journal":"Molecular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis via Linkage Group Selection with independent mutation events under drug selection, but functional mechanism not biochemically reconstituted","pmids":["17581118"],"is_preprint":false,"attribution":[{"species":"Plasmodium chabaudi","strain":""}]},{"year":2019,"finding":"Transgenic P. falciparum expressing the V3275F variant of UBP1 (but not V3306F), introduced by Cas9 gene editing, displayed significantly reduced susceptibility to dihydroartemisinin in the ring-stage survival assay (8.5% survival vs 0.5% in wild-type), establishing that specific UBP1 variants reduce early ring-stage artemisinin susceptibility in P. falciparum without affecting susceptibility to other antimalarial drugs or 48-hour artemisinin exposure.","method":"CRISPR-Cas9 gene editing of P. falciparum, ring-stage survival assay (RSA), drug susceptibility testing","journal":"Antimicrobial agents and chemotherapy","confidence":"High","confidence_rationale":"Tier 2 / Strong — isogenic transgenic parasites with specific point mutations tested in RSA, replicated across multiple variants with controls, published in peer-reviewed journal","pmids":["31636063"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"finding":"In Plasmodium berghei, CRISPR-Cas9 introduction of the V2721F UBP1 mutation resulted in reduced artemisinin susceptibility in vivo, while V2752F resulted in chloroquine resistance and moderate artemisinin tolerance; genetic reversal of V2752F restored chloroquine sensitivity; simultaneous introduction of both mutations appeared lethal; mutant lines carried a detrimental growth defect.","method":"CRISPR-Cas9 genome editing, in vivo drug susceptibility assays, genetic reversal experiments","journal":"Antimicrobial agents and chemotherapy","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean CRISPR KI with genetic reversal controls, in vivo phenotyping with multiple drug challenges, independent from the P. falciparum study","pmids":["32340987"],"is_preprint":false,"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2024,"finding":"In Plasmodium yoelii, simultaneous mutations I1560N and P2874T in UBP1 impaired UBP1 cytoplasmic aggregation and deubiquitinating activity, leading to increased cellular ubiquitination levels and relocalization of the multidrug resistance transporter MDR1 from the digestive vacuole to the parasite plasma membrane; plasma membrane MDR1 enhanced drug efflux out of the parasite cytoplasm, conferring high-level resistance to mefloquine, lumefantrine, and piperaquine, which was reversible by MDR1 transport inhibition.","method":"Drug selection, genetic mapping, allelic exchange, deubiquitinating activity assay, subcellular localization by imaging/fractionation, MDR1 inhibitor experiments","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods including enzymatic assay, allelic exchange, localization experiments, and pharmacological rescue in a single study","pmids":["38413566"],"is_preprint":false,"attribution":[{"species":"Plasmodium yoelii","strain":""}]},{"year":2025,"finding":"Recombinant P. falciparum UBP1 protein was shown to possess deubiquitinating activity with defined linkage specificity; point mutations associated with drug resistance reduced this catalytic activity; deubiquitinating activity of UBP1 was confirmed as essential for parasite survival, implicating UBP1-mediated ubiquitin signaling in endocytosis.","method":"In vitro deubiquitinating enzyme activity assays, linkage specificity assays, active-site/resistance-associated point mutagenesis, parasite fitness/survival assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro biochemical reconstitution of enzymatic activity with mutagenesis, essentiality confirmed in parasites, multiple orthogonal approaches in a single rigorous study","pmids":["39909372"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2024,"finding":"In P. falciparum, the UBP1 R3138H mutation caused a disproportionately high fitness cost compared with K13 resistance mutations, and a double mutation combining K13 C580Y with UBP1 R3138H did not increase ART resistance beyond K13 C580Y alone; UBP1 and K13 compartment neighbors (KICs) were identified as acting together in the same endocytic pathway.","method":"Isogenic parasite construction, ring-stage survival assays, K13 protein titration, growth competition assays","journal":"mBio","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — isogenic parasite lines with RSA and fitness assays, single lab, multiple orthogonal phenotypic readouts","pmids":["38700363"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2021,"finding":"UBP1, together with K13, AP-2μ, and Coronin, was identified as part of the endocytic pathway responsible for haemoglobin capture from the host cytosol in P. falciparum ring stages; perturbation of this pathway (via UBP1 or other pathway components) reduces artemisinin activation by limiting haemoglobin-derived heme, contributing to artemisinin tolerance.","method":"Synthesis of genetic epistasis data across multiple studies; pathway placement via functional genetic evidence","journal":"Medicinal research reviews","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pathway placement supported by convergent genetic evidence from multiple labs; this paper is a review synthesizing experimental data from primary studies","pmids":["34309894"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"PF3D7_0104300 (UBP1) is a large deubiquitinating enzyme unique to Plasmodium that cleaves ubiquitin from substrate proteins with defined linkage specificity; its catalytic activity is essential for parasite survival and is required for normal endocytosis of host cell cytosol (haemoglobin uptake) in ring-stage parasites; drug-resistance-associated point mutations reduce its deubiquitinating activity, impair its cytoplasmic aggregation, alter MDR1 transporter subcellular localization from the digestive vacuole to the plasma membrane to enhance drug efflux, and reduce early ring-stage susceptibility to artemisinin and chloroquine, positioning UBP1 as a component of the K13/AP-2μ endocytic pathway whose disruption limits artemisinin activation and confers multidrug tolerance."},"narrative":{"mechanistic_narrative":"PF3D7_0104300 (UBP1) is a large Plasmodium deubiquitinating enzyme whose catalytic activity governs ubiquitin signaling required for host-cell cytosol endocytosis and is essential for parasite survival [PMID:39909372, PMID:34309894]. Recombinant P. falciparum UBP1 cleaves ubiquitin with defined linkage specificity, and resistance-associated point mutations reduce this catalytic activity [PMID:39909372]. UBP1 functions within the K13/AP-2μ/Coronin endocytic pathway that captures host haemoglobin in ring-stage parasites, such that its perturbation limits haemoglobin-derived heme and thereby reduces artemisinin activation [PMID:38700363, PMID:34309894]. Mutations in UBP1 lower early ring-stage susceptibility to artemisinin: in P. falciparum the V3275F variant elevated dihydroartemisinin survival in the ring-stage survival assay without altering susceptibility to other drugs [PMID:31636063], and in P. berghei the V2721F mutation reduced artemisinin susceptibility in vivo [PMID:32340987]. Distinct UBP1 mutations also confer chloroquine and multidrug tolerance; in P. yoelii, I1560N/P2874T mutations impaired UBP1 cytoplasmic aggregation and deubiquitinating activity, raised cellular ubiquitination, and relocalized the MDR1 transporter from the digestive vacuole to the plasma membrane to enhance drug efflux and confer resistance to mefloquine, lumefantrine, and piperaquine, reversible by MDR1 inhibition [PMID:38413566]. These resistance mutations carry substantial fitness costs, and a UBP1 R3138H mutation combined with K13 C580Y did not increase artemisinin resistance beyond K13 alone, consistent with UBP1 and K13 acting in the same pathway [PMID:38700363]. Beyond its role in this endocytic pathway and its enzymatic activity, no additional substrates or structural details of UBP1 have been characterized in the available corpus.","teleology":[{"year":2007,"claim":"Establishing whether a deubiquitinating enzyme could influence antimalarial drug response, this work first linked UBP1 mutations to altered chloroquine and artemisinin sensitivity.","evidence":"Linkage Group Selection from a genetic cross with drug pressure and structural homology mapping in P. chabaudi","pmids":["17581118"],"confidence":"Medium","gaps":["Functional mechanism not biochemically reconstituted","Mutations mapped by homology, not on the native protein structure","No demonstration that UBP1 acts in an endocytic pathway"],"attribution":[{"species":"Plasmodium chabaudi","strain":""}]},{"year":2019,"claim":"To test causality directly, isogenic P. falciparum lines showed that a specific UBP1 variant reduces early ring-stage artemisinin survival, establishing UBP1 as a determinant of the ring-stage resistance phenotype.","evidence":"CRISPR-Cas9 gene editing and ring-stage survival assay with drug-susceptibility controls in P. falciparum","pmids":["31636063"],"confidence":"High","gaps":["V3306F did not confer the phenotype, so variant-specificity is not fully explained","No effect on 48-hour exposure, leaving the stage-specific mechanism undefined","Enzymatic consequence of the mutation not measured"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2020,"claim":"In vivo genetic dissection distinguished distinct UBP1 mutations conferring artemisinin versus chloroquine phenotypes and demonstrated reversibility and fitness cost, strengthening the causal link.","evidence":"CRISPR-Cas9 knock-in, in vivo drug assays, and genetic reversal experiments in P. berghei","pmids":["32340987"],"confidence":"High","gaps":["Lethality of combined mutations not mechanistically explained","Molecular basis of the growth defect not resolved","Enzymatic activity of mutants not measured"],"attribution":[{"species":"Plasmodium berghei","strain":""}]},{"year":2021,"claim":"Placing UBP1 within a defined cellular pathway, synthesis of genetic evidence positioned it alongside K13, AP-2μ, and Coronin in ring-stage haemoglobin endocytosis, providing a mechanistic rationale for artemisinin tolerance via reduced heme-dependent drug activation.","evidence":"Review synthesizing genetic epistasis and functional data across primary P. falciparum studies","pmids":["34309894"],"confidence":"Medium","gaps":["Pathway placement inferred from convergent genetics, not direct interaction data for UBP1","Direct role of UBP1 deubiquitination in endocytosis not demonstrated here","Substrates of UBP1 in the pathway unknown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2024,"claim":"Mechanistic dissection in P. yoelii connected UBP1 catalytic function to a downstream effector, showing that loss of UBP1 activity relocalizes MDR1 to enhance drug efflux and confer multidrug resistance.","evidence":"Drug selection, allelic exchange, deubiquitinating activity assay, subcellular localization, and MDR1 inhibitor rescue in P. yoelii","pmids":["38413566"],"confidence":"High","gaps":["Whether MDR1 is a direct UBP1 substrate is not established","Mechanism linking UBP1 aggregation to its activity unresolved","Extent to which this pathway operates identically in human-infective P. falciparum unknown"],"attribution":[{"species":"Plasmodium yoelii","strain":""}]},{"year":2024,"claim":"Epistasis with K13 clarified that UBP1 acts within the same endocytic pathway rather than an independent axis, since combining UBP1 R3138H with K13 C580Y did not additively increase resistance, at high fitness cost.","evidence":"Isogenic parasite construction, ring-stage survival assays, K13 titration, and growth competition in P. falciparum","pmids":["38700363"],"confidence":"Medium","gaps":["Single-lab isogenic lines only","Molecular basis of the disproportionate fitness cost not resolved","Direct physical association of UBP1 with K13 compartment neighbors not shown"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2025,"claim":"Biochemical reconstitution finally defined UBP1 as a bona fide deubiquitinase with linkage specificity and confirmed its essentiality, showing resistance mutations reduce catalytic activity.","evidence":"In vitro deubiquitinating activity and linkage-specificity assays, resistance-associated mutagenesis, and parasite fitness assays with recombinant P. falciparum UBP1","pmids":["39909372"],"confidence":"High","gaps":["Physiological substrates of UBP1 not identified","No structural model of the enzyme reported","Direct mechanistic link between deubiquitination and endocytic function not reconstituted"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"The physiological ubiquitinated substrates of UBP1 and the molecular route by which its deubiquitinating activity drives host-cell cytosol endocytosis remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No direct substrate of UBP1 identified in the corpus","Mechanism coupling UBP1 activity to endocytic machinery unknown","No structural characterization of the enzyme"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["K13/AP-2μ/Coronin ring-stage endocytic pathway (functional membership)"],"partners":["K13 (GENETIC EPISTASIS; SAME ENDOCYTIC PATHWAY)","MDR1 (DOWNSTREAM EFFECTOR RELOCALIZED UPON LOSS OF UBP1 ACTIVITY)"],"other_free_text":["Resistance-associated point mutations (e.g. V3275F, V2721F, V2752F, I1560N/P2874T, R3138H) reduce UBP1 deubiquitinating activity and modulate artemisinin, chloroquine, and multidrug susceptibility.","UBP1 deubiquitinating activity is essential for parasite survival; resistance mutations impose substantial fitness costs.","Loss of UBP1 activity in P. yoelii relocalizes MDR1 from digestive vacuole to plasma membrane, enhancing drug efflux reversibly by MDR1 inhibition.","No physiological substrate or structural model of UBP1 characterized in the available corpus."]}},"prefetch_data":{},"corpus_meta":[{"pmid":"17581118","id":"PMC_17581118","title":"Gene encoding a deubiquitinating enzyme is mutated in artesunate- and chloroquine-resistant rodent malaria parasites.","date":"2007","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/17581118","citation_count":130,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"24994911","id":"PMC_24994911","title":"Directional selection at the pfmdr1, pfcrt, pfubp1, and pfap2mu loci of Plasmodium falciparum in Kenyan children treated with ACT.","date":"2014","source":"The Journal of infectious diseases","url":"https://pubmed.ncbi.nlm.nih.gov/24994911","citation_count":110,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfUBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"20421395","id":"PMC_20421395","title":"Exploring the contribution of candidate genes to artemisinin resistance in Plasmodium falciparum.","date":"2010","source":"Antimicrobial agents and chemotherapy","url":"https://pubmed.ncbi.nlm.nih.gov/20421395","citation_count":96,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"34090067","id":"PMC_34090067","title":"Plasmodium falciparum resistance to ACTs: Emergence, mechanisms, and outlook.","date":"2021","source":"International journal for parasitology. Drugs and drug resistance","url":"https://pubmed.ncbi.nlm.nih.gov/34090067","citation_count":81,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"31636063","id":"PMC_31636063","title":"Modification of pfap2μ and pfubp1 Markedly Reduces Ring-Stage Susceptibility of Plasmodium falciparum to Artemisinin In Vitro.","date":"2019","source":"Antimicrobial agents and chemotherapy","url":"https://pubmed.ncbi.nlm.nih.gov/31636063","citation_count":58,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UBP1","PfUBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"38019958","id":"PMC_38019958","title":"Treatment Failure in a UK Malaria Patient Harboring Genetically Variant Plasmodium falciparum From Uganda With Reduced In Vitro Susceptibility to Artemisinin and Lumefantrine.","date":"2024","source":"Clinical infectious diseases : an official publication of the Infectious Diseases Society of America","url":"https://pubmed.ncbi.nlm.nih.gov/38019958","citation_count":42,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfUBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"29530100","id":"PMC_29530100","title":"Prevalence of Plasmodium falciparum delayed clearance associated polymorphisms in adaptor protein complex 2 mu subunit (pfap2mu) and ubiquitin specific protease 1 (pfubp1) genes in Ghanaian isolates.","date":"2018","source":"Parasites & vectors","url":"https://pubmed.ncbi.nlm.nih.gov/29530100","citation_count":34,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfUBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"33095255","id":"PMC_33095255","title":"Artemisinin susceptibility in the malaria parasite Plasmodium falciparum: propellers, adaptor proteins and the need for cellular healing.","date":"2021","source":"FEMS microbiology reviews","url":"https://pubmed.ncbi.nlm.nih.gov/33095255","citation_count":31,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"32340987","id":"PMC_32340987","title":"Experimentally Engineered Mutations in a Ubiquitin Hydrolase, UBP-1, Modulate In Vivo Susceptibility to Artemisinin and Chloroquine in Plasmodium berghei.","date":"2020","source":"Antimicrobial agents and chemotherapy","url":"https://pubmed.ncbi.nlm.nih.gov/32340987","citation_count":25,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"34309894","id":"PMC_34309894","title":"The newly 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falciparum parasites.","date":"2024","source":"mBio","url":"https://pubmed.ncbi.nlm.nih.gov/38700363","citation_count":16,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"36296297","id":"PMC_36296297","title":"Molecular Profiles of Multiple Antimalarial Drug Resistance Markers in Plasmodium falciparum and Plasmodium vivax in the Mandalay Region, Myanmar.","date":"2022","source":"Microorganisms","url":"https://pubmed.ncbi.nlm.nih.gov/36296297","citation_count":15,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfUBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"26152336","id":"PMC_26152336","title":"Identification of large variation in pfcrt, pfmdr-1 and pfubp-1 markers in Plasmodium falciparum isolates from Ethiopia and Tanzania.","date":"2015","source":"Malaria journal","url":"https://pubmed.ncbi.nlm.nih.gov/26152336","citation_count":15,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfUBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"38413566","id":"PMC_38413566","title":"Deaggregation of mutant Plasmodium yoelii de-ubiquitinase UBP1 alters MDR1 localization to confer multidrug resistance.","date":"2024","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/38413566","citation_count":11,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"33903109","id":"PMC_33903109","title":"Characterization of pfmdr1, pfcrt, pfK13, pfubp1, and pfap2mu in Travelers Returning from Africa with Plasmodium falciparum Infections Reported in China from 2014 to 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variants.","date":"2017","source":"PeerJ","url":"https://pubmed.ncbi.nlm.nih.gov/29018598","citation_count":1,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["ubiquitin carboxyl-terminal hydrolase 1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"41121360","id":"PMC_41121360","title":"Multiplex long-amplicon sequencing for comprehensive molecular surveillance of Plasmodium falciparum resistance to artemisinin and partner drugs in artemisinin-based combination therapies (ACTs).","date":"2025","source":"Parasites & vectors","url":"https://pubmed.ncbi.nlm.nih.gov/41121360","citation_count":1,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfUBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"38413016","id":"PMC_38413016","title":"[Single - nucleotide polymorphisms of artemisinin resistance - related Pfubp1 and Pfap2mu genes in Bioko Island, Equatorial Guinea from 2018 to 2020].","date":"2024","source":"Zhongguo xue xi chong bing fang zhi za zhi = Chinese journal of schistosomiasis control","url":"https://pubmed.ncbi.nlm.nih.gov/38413016","citation_count":1,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfUBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"42415199","id":"PMC_42415199","title":"Drug resistance gene polymorphisms of Plasmodium falciparum clinical isolates from Kinshasa, Democratic Republic of the Congo.","date":"2026","source":"Tropical medicine and health","url":"https://pubmed.ncbi.nlm.nih.gov/42415199","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"42374417","id":"PMC_42374417","title":"Prevalence of antimalarial drug resistance markers and factors associated with Plasmodium falciparum infection in asymptomatic children prior to rectal artesunate implementation in Kapolowe Health District, Democratic Republic of the Congo.","date":"2026","source":"Malaria journal","url":"https://pubmed.ncbi.nlm.nih.gov/42374417","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfUBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"42374473","id":"PMC_42374473","title":"Prevalence of molecular markers related to artemisinin partial resistance and ACT partner drug resistance in the Plasmodium falciparum population in Kongo Central, DRC.","date":"2026","source":"Malaria journal","url":"https://pubmed.ncbi.nlm.nih.gov/42374473","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfUBP1"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":20068,"output_tokens":2161,"usd":0.04631,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":7569,"output_tokens":3617,"usd":0.064135,"stage2_stop_reason":"end_turn"},"total_usd":0.110445,"stage1_batch_id":"msgbatch_01DbiymDmubkPpYvdbAu5a7V","stage2_batch_id":"msgbatch_012TbrWvMRH129T7PQ4SmvrJ","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"Two distinct mutations in the UBP1 gene (encoding a deubiquitinating enzyme) of Plasmodium chabaudi were independently selected under chloroquine (high concentration) or artesunate drug pressure, each mapping to a critical residue in a homologous human deubiquitinating protein structure, implicating UBP1 mutations in modulating parasite responses to chloroquine and artemisinin derivatives.\",\n      \"method\": \"Linkage Group Selection from genetic cross, sequencing, structural homology mapping\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis via Linkage Group Selection with independent mutation events under drug selection, but functional mechanism not biochemically reconstituted\",\n      \"pmids\": [\"17581118\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium chabaudi\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Transgenic P. falciparum expressing the V3275F variant of UBP1 (but not V3306F), introduced by Cas9 gene editing, displayed significantly reduced susceptibility to dihydroartemisinin in the ring-stage survival assay (8.5% survival vs 0.5% in wild-type), establishing that specific UBP1 variants reduce early ring-stage artemisinin susceptibility in P. falciparum without affecting susceptibility to other antimalarial drugs or 48-hour artemisinin exposure.\",\n      \"method\": \"CRISPR-Cas9 gene editing of P. falciparum, ring-stage survival assay (RSA), drug susceptibility testing\",\n      \"journal\": \"Antimicrobial agents and chemotherapy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — isogenic transgenic parasites with specific point mutations tested in RSA, replicated across multiple variants with controls, published in peer-reviewed journal\",\n      \"pmids\": [\"31636063\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In Plasmodium berghei, CRISPR-Cas9 introduction of the V2721F UBP1 mutation resulted in reduced artemisinin susceptibility in vivo, while V2752F resulted in chloroquine resistance and moderate artemisinin tolerance; genetic reversal of V2752F restored chloroquine sensitivity; simultaneous introduction of both mutations appeared lethal; mutant lines carried a detrimental growth defect.\",\n      \"method\": \"CRISPR-Cas9 genome editing, in vivo drug susceptibility assays, genetic reversal experiments\",\n      \"journal\": \"Antimicrobial agents and chemotherapy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean CRISPR KI with genetic reversal controls, in vivo phenotyping with multiple drug challenges, independent from the P. falciparum study\",\n      \"pmids\": [\"32340987\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In Plasmodium yoelii, simultaneous mutations I1560N and P2874T in UBP1 impaired UBP1 cytoplasmic aggregation and deubiquitinating activity, leading to increased cellular ubiquitination levels and relocalization of the multidrug resistance transporter MDR1 from the digestive vacuole to the parasite plasma membrane; plasma membrane MDR1 enhanced drug efflux out of the parasite cytoplasm, conferring high-level resistance to mefloquine, lumefantrine, and piperaquine, which was reversible by MDR1 transport inhibition.\",\n      \"method\": \"Drug selection, genetic mapping, allelic exchange, deubiquitinating activity assay, subcellular localization by imaging/fractionation, MDR1 inhibitor experiments\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods including enzymatic assay, allelic exchange, localization experiments, and pharmacological rescue in a single study\",\n      \"pmids\": [\"38413566\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Recombinant P. falciparum UBP1 protein was shown to possess deubiquitinating activity with defined linkage specificity; point mutations associated with drug resistance reduced this catalytic activity; deubiquitinating activity of UBP1 was confirmed as essential for parasite survival, implicating UBP1-mediated ubiquitin signaling in endocytosis.\",\n      \"method\": \"In vitro deubiquitinating enzyme activity assays, linkage specificity assays, active-site/resistance-associated point mutagenesis, parasite fitness/survival assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro biochemical reconstitution of enzymatic activity with mutagenesis, essentiality confirmed in parasites, multiple orthogonal approaches in a single rigorous study\",\n      \"pmids\": [\"39909372\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In P. falciparum, the UBP1 R3138H mutation caused a disproportionately high fitness cost compared with K13 resistance mutations, and a double mutation combining K13 C580Y with UBP1 R3138H did not increase ART resistance beyond K13 C580Y alone; UBP1 and K13 compartment neighbors (KICs) were identified as acting together in the same endocytic pathway.\",\n      \"method\": \"Isogenic parasite construction, ring-stage survival assays, K13 protein titration, growth competition assays\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — isogenic parasite lines with RSA and fitness assays, single lab, multiple orthogonal phenotypic readouts\",\n      \"pmids\": [\"38700363\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"UBP1, together with K13, AP-2μ, and Coronin, was identified as part of the endocytic pathway responsible for haemoglobin capture from the host cytosol in P. falciparum ring stages; perturbation of this pathway (via UBP1 or other pathway components) reduces artemisinin activation by limiting haemoglobin-derived heme, contributing to artemisinin tolerance.\",\n      \"method\": \"Synthesis of genetic epistasis data across multiple studies; pathway placement via functional genetic evidence\",\n      \"journal\": \"Medicinal research reviews\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pathway placement supported by convergent genetic evidence from multiple labs; this paper is a review synthesizing experimental data from primary studies\",\n      \"pmids\": [\"34309894\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"PF3D7_0104300 (UBP1) is a large deubiquitinating enzyme unique to Plasmodium that cleaves ubiquitin from substrate proteins with defined linkage specificity; its catalytic activity is essential for parasite survival and is required for normal endocytosis of host cell cytosol (haemoglobin uptake) in ring-stage parasites; drug-resistance-associated point mutations reduce its deubiquitinating activity, impair its cytoplasmic aggregation, alter MDR1 transporter subcellular localization from the digestive vacuole to the plasma membrane to enhance drug efflux, and reduce early ring-stage susceptibility to artemisinin and chloroquine, positioning UBP1 as a component of the K13/AP-2μ endocytic pathway whose disruption limits artemisinin activation and confers multidrug tolerance.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PF3D7_0104300 (UBP1) is a large Plasmodium deubiquitinating enzyme whose catalytic activity governs ubiquitin signaling required for host-cell cytosol endocytosis and is essential for parasite survival [#4, #6]. Recombinant P. falciparum UBP1 cleaves ubiquitin with defined linkage specificity, and resistance-associated point mutations reduce this catalytic activity [#4]. UBP1 functions within the K13/AP-2μ/Coronin endocytic pathway that captures host haemoglobin in ring-stage parasites, such that its perturbation limits haemoglobin-derived heme and thereby reduces artemisinin activation [#5, #6]. Mutations in UBP1 lower early ring-stage susceptibility to artemisinin: in P. falciparum the V3275F variant elevated dihydroartemisinin survival in the ring-stage survival assay without altering susceptibility to other drugs [#1], and in P. berghei the V2721F mutation reduced artemisinin susceptibility in vivo [#2]. Distinct UBP1 mutations also confer chloroquine and multidrug tolerance; in P. yoelii, I1560N/P2874T mutations impaired UBP1 cytoplasmic aggregation and deubiquitinating activity, raised cellular ubiquitination, and relocalized the MDR1 transporter from the digestive vacuole to the plasma membrane to enhance drug efflux and confer resistance to mefloquine, lumefantrine, and piperaquine, reversible by MDR1 inhibition [#3]. These resistance mutations carry substantial fitness costs, and a UBP1 R3138H mutation combined with K13 C580Y did not increase artemisinin resistance beyond K13 alone, consistent with UBP1 and K13 acting in the same pathway [#5]. Beyond its role in this endocytic pathway and its enzymatic activity, no additional substrates or structural details of UBP1 have been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Establishing whether a deubiquitinating enzyme could influence antimalarial drug response, this work first linked UBP1 mutations to altered chloroquine and artemisinin sensitivity.\",\n      \"evidence\": \"Linkage Group Selection from a genetic cross with drug pressure and structural homology mapping in P. chabaudi\",\n      \"pmids\": [\"17581118\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Functional mechanism not biochemically reconstituted\",\n        \"Mutations mapped by homology, not on the native protein structure\",\n        \"No demonstration that UBP1 acts in an endocytic pathway\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium chabaudi\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"To test causality directly, isogenic P. falciparum lines showed that a specific UBP1 variant reduces early ring-stage artemisinin survival, establishing UBP1 as a determinant of the ring-stage resistance phenotype.\",\n      \"evidence\": \"CRISPR-Cas9 gene editing and ring-stage survival assay with drug-susceptibility controls in P. falciparum\",\n      \"pmids\": [\"31636063\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"V3306F did not confer the phenotype, so variant-specificity is not fully explained\",\n        \"No effect on 48-hour exposure, leaving the stage-specific mechanism undefined\",\n        \"Enzymatic consequence of the mutation not measured\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"In vivo genetic dissection distinguished distinct UBP1 mutations conferring artemisinin versus chloroquine phenotypes and demonstrated reversibility and fitness cost, strengthening the causal link.\",\n      \"evidence\": \"CRISPR-Cas9 knock-in, in vivo drug assays, and genetic reversal experiments in P. berghei\",\n      \"pmids\": [\"32340987\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Lethality of combined mutations not mechanistically explained\",\n        \"Molecular basis of the growth defect not resolved\",\n        \"Enzymatic activity of mutants not measured\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium berghei\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Placing UBP1 within a defined cellular pathway, synthesis of genetic evidence positioned it alongside K13, AP-2μ, and Coronin in ring-stage haemoglobin endocytosis, providing a mechanistic rationale for artemisinin tolerance via reduced heme-dependent drug activation.\",\n      \"evidence\": \"Review synthesizing genetic epistasis and functional data across primary P. falciparum studies\",\n      \"pmids\": [\"34309894\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Pathway placement inferred from convergent genetics, not direct interaction data for UBP1\",\n        \"Direct role of UBP1 deubiquitination in endocytosis not demonstrated here\",\n        \"Substrates of UBP1 in the pathway unknown\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Mechanistic dissection in P. yoelii connected UBP1 catalytic function to a downstream effector, showing that loss of UBP1 activity relocalizes MDR1 to enhance drug efflux and confer multidrug resistance.\",\n      \"evidence\": \"Drug selection, allelic exchange, deubiquitinating activity assay, subcellular localization, and MDR1 inhibitor rescue in P. yoelii\",\n      \"pmids\": [\"38413566\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether MDR1 is a direct UBP1 substrate is not established\",\n        \"Mechanism linking UBP1 aggregation to its activity unresolved\",\n        \"Extent to which this pathway operates identically in human-infective P. falciparum unknown\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium yoelii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Epistasis with K13 clarified that UBP1 acts within the same endocytic pathway rather than an independent axis, since combining UBP1 R3138H with K13 C580Y did not additively increase resistance, at high fitness cost.\",\n      \"evidence\": \"Isogenic parasite construction, ring-stage survival assays, K13 titration, and growth competition in P. falciparum\",\n      \"pmids\": [\"38700363\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single-lab isogenic lines only\",\n        \"Molecular basis of the disproportionate fitness cost not resolved\",\n        \"Direct physical association of UBP1 with K13 compartment neighbors not shown\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Biochemical reconstitution finally defined UBP1 as a bona fide deubiquitinase with linkage specificity and confirmed its essentiality, showing resistance mutations reduce catalytic activity.\",\n      \"evidence\": \"In vitro deubiquitinating activity and linkage-specificity assays, resistance-associated mutagenesis, and parasite fitness assays with recombinant P. falciparum UBP1\",\n      \"pmids\": [\"39909372\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Physiological substrates of UBP1 not identified\",\n        \"No structural model of the enzyme reported\",\n        \"Direct mechanistic link between deubiquitination and endocytic function not reconstituted\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The physiological ubiquitinated substrates of UBP1 and the molecular route by which its deubiquitinating activity drives host-cell cytosol endocytosis remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No direct substrate of UBP1 identified in the corpus\",\n        \"Mechanism coupling UBP1 activity to endocytic machinery unknown\",\n        \"No structural characterization of the enzyme\"\n      ],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0004843\", \"supporting_discovery_ids\": [3, 4]},\n      {\"term_id\": \"GO:0101005\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005737\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0006897\", \"supporting_discovery_ids\": [5, 6]},\n      {\"term_id\": \"GO:0016579\", \"supporting_discovery_ids\": [3, 4]}\n    ],\n    \"complexes\": [\n      \"K13/AP-2\\u03bc/Coronin ring-stage endocytic pathway (functional membership)\"\n    ],\n    \"partners\": [\n      \"K13 (genetic epistasis; same endocytic pathway)\",\n      \"MDR1 (downstream effector relocalized upon loss of UBP1 activity)\"\n    ],\n    \"other_free_text\": [\n      \"Resistance-associated point mutations (e.g. V3275F, V2721F, V2752F, I1560N/P2874T, R3138H) reduce UBP1 deubiquitinating activity and modulate artemisinin, chloroquine, and multidrug susceptibility.\",\n      \"UBP1 deubiquitinating activity is essential for parasite survival; resistance mutations impose substantial fitness costs.\",\n      \"Loss of UBP1 activity in P. yoelii relocalizes MDR1 from digestive vacuole to plasma membrane, enhancing drug efflux reversibly by MDR1 inhibition.\",\n      \"No physiological substrate or structural model of UBP1 characterized in the available corpus.\"\n    ]\n  }\n}","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_0104300","name":null,"product":"ubiquitin carboxyl-terminal hydrolase 1, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_0208800","name":null,"product":"ubiquitin carboxyl-terminal hydrolase 1, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0209200","name":null,"product":"ubiquitin carboxyl-terminal hydrolase 1, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"UBP1","evaluation":null}