{"gene":"PF3D7_1117100","run_date":"2026-09-08T19:44:17","timeline":{"discoveries":[{"year":2006,"finding":"UCH54 (PfUCH54) was identified as the first deubiquitinating enzyme in P. falciparum by activity-based protein profiling using ubiquitin-derived electrophilic probes on schizont lysate; it was shown to have deubiquitinating activity and, uniquely, also deNeddylating activity (using a mammalian Nedd8-based probe), an activity absent from its mammalian homologues.","method":"Activity-based protein profiling (ABPP) with ubiquitin and Nedd8 electrophilic probes, SDS-PAGE/immunoblotting, mass spectrometry identification; N-ethylmaleimide inhibition demonstrated involvement of a reactive cysteine residue.","journal":"Molecular microbiology","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — direct enzymatic activity demonstrated with chemical probes plus cysteine-dependence confirmed by NEM inhibition; landmark paper replicated conceptually in subsequent studies.","pmids":["16925553"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"finding":"UCH54 (PfUCH54) was identified as a substoichiometric, transient or weakly interacting component of the P. falciparum 26S proteasome complex, consistent with its role as a proteasome-associated deubiquitinase (homolog of UCH37/proteasome-interacting protein).","method":"Affinity purification of functional 26S proteasome complexes from P. falciparum, in situ protein crosslinking, and mass spectrometry-based subunit quantification (NSAF method).","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — affinity purification with in situ crosslinking and quantitative MS from a single lab; substoichiometric recovery indicates transient association but no functional mutagenesis performed.","pmids":["26639022"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"finding":"UCH54 (PfUCH54) was confirmed to react with both ubiquitin- and Nedd8-based activity-based probes, establishing dual deubiquitinating/deNeddylating specificity; the study also used functional chemical probes to show that deNeddylation in P. falciparum is controlled by a different set of enzymes compared to the human host.","method":"Functional chemical probes (ubiquitin- and Nedd8-based ABPs), parasite transgenics, and drug assays.","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — corroborates earlier ABPP finding with additional chemical biology; primary mechanistic focus of this paper is on PfUCH37, with UCH54 mentioned as reacting with both probes but not functionally dissected independently.","pmids":["31658303"],"is_preprint":false,"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"current_model":"UCH54 (PF3D7_1117100) is a cysteine-dependent deubiquitinating enzyme in P. falciparum that possesses dual deubiquitinating and deNeddylating activities (the latter absent from its mammalian homologues), associates transiently and substoichiometrically with the P. falciparum 26S proteasome complex as a proteasome-interacting deubiquitinase, and its activities are sensitive to N-ethylmaleimide, indicating dependence on an active-site cysteine residue."},"narrative":{"mechanistic_narrative":"UCH54 (PF3D7_1117100) is a cysteine-dependent deubiquitinating enzyme of Plasmodium falciparum that was the first deubiquitinase identified in the parasite [PMID:16925553]. It possesses dual specificity, reacting with both ubiquitin- and Nedd8-based activity-based probes and thereby displaying both deubiquitinating and deNeddylating activity — the latter being absent from its mammalian homologues [PMID:16925553, PMID:31658303]. Its reactivity is abolished by N-ethylmaleimide, indicating dependence on an active-site cysteine [PMID:16925553]. UCH54 associates transiently and substoichiometrically with the P. falciparum 26S proteasome complex, consistent with a role as a proteasome-interacting deubiquitinase [PMID:26639022]. Beyond these activity-based and association findings, the specific substrates, structural basis of catalysis, and cellular consequences of UCH54 activity have not been characterized in the available corpus.","teleology":[{"year":2006,"claim":"Whether P. falciparum possesses an active deubiquitinating enzyme was unknown; activity-based profiling identified UCH54 as the first such enzyme and revealed an unexpected dual deubiquitinating/deNeddylating activity not seen in mammalian homologues.","evidence":"Activity-based protein profiling of schizont lysate with ubiquitin and Nedd8 electrophilic probes, mass spectrometry identification, and N-ethylmaleimide inhibition to confirm active-site cysteine dependence","pmids":["16925553"],"confidence":"High","gaps":["No functional substrate identified in the parasite","Catalytic cysteine not pinpointed by mutagenesis","Cellular role and phenotype of loss not tested"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2015,"claim":"How UCH54 relates to the parasite proteolytic machinery was unresolved; quantitative proteomics of purified proteasomes placed UCH54 as a transient, substoichiometric proteasome-associated deubiquitinase.","evidence":"Affinity purification of functional 26S proteasome complexes from P. falciparum with in situ crosslinking and NSAF-based quantitative mass spectrometry","pmids":["26639022"],"confidence":"Medium","gaps":["Association shown by co-purification only, no functional mutagenesis","Direct binding interface with the proteasome not mapped","Substoichiometric recovery leaves the fraction of proteasome-bound UCH54 undefined"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":2019,"claim":"Whether the dual ubiquitin/Nedd8 reactivity was reproducible and how parasite deNeddylation differs from the host was open; chemical probe profiling confirmed UCH54 reacts with both probe types within a broader distinction between parasite and human deNeddylation enzymes.","evidence":"Functional ubiquitin- and Nedd8-based activity-based probes with parasite transgenics and drug assays","pmids":["31658303"],"confidence":"Medium","gaps":["UCH54 was not functionally dissected independently in this study, which focused on a sibling enzyme","Relative contribution of UCH54 versus other enzymes to parasite deNeddylation not quantified","No structural or kinetic characterization"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]},{"year":null,"claim":"The endogenous substrates, catalytic residue identity, structural basis of dual ubiquitin/Nedd8 specificity, and the physiological consequence of UCH54 activity or its proteasome association remain unknown.","evidence":"","pmids":[],"confidence":"Low","gaps":["No physiological substrate defined","No genetic knockout/knockdown phenotype reported","No structure or catalytic mutant characterized"],"attribution":[{"species":"Plasmodium falciparum","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["26S proteasome (transient, substoichiometric association)"],"partners":["P. FALCIPARUM 26S PROTEASOME COMPLEX"],"other_free_text":["First deubiquitinating enzyme identified in P. falciparum by activity-based protein profiling.","Displays dual deubiquitinating and deNeddylating activity, the latter absent from mammalian homologues.","Activity is N-ethylmaleimide-sensitive, indicating dependence on an active-site cysteine.","Homolog of UCH37/proteasome-interacting deubiquitinase; associates transiently and substoichiometrically with the 26S proteasome."]}},"prefetch_data":{},"corpus_meta":[{"pmid":"16925553","id":"PMC_16925553","title":"Identification by functional proteomics of a deubiquitinating/deNeddylating enzyme in Plasmodium falciparum.","date":"2006","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/16925553","citation_count":65,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["PfUCH54"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"31658303","id":"PMC_31658303","title":"Nedd8 hydrolysis by UCH proteases in Plasmodium parasites.","date":"2019","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/31658303","citation_count":23,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["curated_ref"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"40278767","id":"","title":"Combating Malaria: Targeting the Ubiquitin-Proteasome System to Conquer Drug Resistance.","date":"2025","source":"Tropical medicine and infectious disease","url":"https://pubmed.ncbi.nlm.nih.gov/40278767","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UCH54"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"38411954","id":"","title":"Neddylation is essential for malaria transmission in Plasmodium berghei.","date":"2024","source":"mBio","url":"https://pubmed.ncbi.nlm.nih.gov/38411954","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UCH54"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"35506504","id":"","title":"The Impact of Activity-Based Protein Profiling in Malaria Drug Discovery.","date":"2022","source":"ChemMedChem","url":"https://pubmed.ncbi.nlm.nih.gov/35506504","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UCH54"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"36237424","id":"","title":"The emerging role of Deubiquitinases (DUBs) in parasites: A foresight review.","date":"2022","source":"Frontiers in cellular and infection microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/36237424","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UCH54"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"31170268","id":"","title":"Covalent Plasmodium falciparum-selective proteasome inhibitors exhibit a low propensity for generating resistance in vitro and synergize with multiple antimalarial agents.","date":"2019","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/31170268","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UCH54"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"28599096","id":"","title":"Proteases as antimalarial targets: strategies for genetic, chemical, and therapeutic validation.","date":"2017","source":"The FEBS journal","url":"https://pubmed.ncbi.nlm.nih.gov/28599096","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UCH54"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false},{"pmid":"26639022","id":"","title":"Characterization of the 26S proteasome network in Plasmodium falciparum.","date":"2015","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/26639022","citation_count":0,"is_preprint":false,"source_species":["Pf"],"role":"primary","match_terms":["UCH54"],"competing_organism_flag":false,"competing_organism_match":"","competing_organism_only":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10615,"output_tokens":1053,"usd":0.02382,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":5800,"output_tokens":1964,"usd":0.03905,"stage2_stop_reason":"end_turn"},"total_usd":0.06287,"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\": 2006,\n      \"finding\": \"UCH54 (PfUCH54) was identified as the first deubiquitinating enzyme in P. falciparum by activity-based protein profiling using ubiquitin-derived electrophilic probes on schizont lysate; it was shown to have deubiquitinating activity and, uniquely, also deNeddylating activity (using a mammalian Nedd8-based probe), an activity absent from its mammalian homologues.\",\n      \"method\": \"Activity-based protein profiling (ABPP) with ubiquitin and Nedd8 electrophilic probes, SDS-PAGE/immunoblotting, mass spectrometry identification; N-ethylmaleimide inhibition demonstrated involvement of a reactive cysteine residue.\",\n      \"journal\": \"Molecular microbiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — direct enzymatic activity demonstrated with chemical probes plus cysteine-dependence confirmed by NEM inhibition; landmark paper replicated conceptually in subsequent studies.\",\n      \"pmids\": [\"16925553\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"UCH54 (PfUCH54) was identified as a substoichiometric, transient or weakly interacting component of the P. falciparum 26S proteasome complex, consistent with its role as a proteasome-associated deubiquitinase (homolog of UCH37/proteasome-interacting protein).\",\n      \"method\": \"Affinity purification of functional 26S proteasome complexes from P. falciparum, in situ protein crosslinking, and mass spectrometry-based subunit quantification (NSAF method).\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — affinity purification with in situ crosslinking and quantitative MS from a single lab; substoichiometric recovery indicates transient association but no functional mutagenesis performed.\",\n      \"pmids\": [\"26639022\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"UCH54 (PfUCH54) was confirmed to react with both ubiquitin- and Nedd8-based activity-based probes, establishing dual deubiquitinating/deNeddylating specificity; the study also used functional chemical probes to show that deNeddylation in P. falciparum is controlled by a different set of enzymes compared to the human host.\",\n      \"method\": \"Functional chemical probes (ubiquitin- and Nedd8-based ABPs), parasite transgenics, and drug assays.\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — corroborates earlier ABPP finding with additional chemical biology; primary mechanistic focus of this paper is on PfUCH37, with UCH54 mentioned as reacting with both probes but not functionally dissected independently.\",\n      \"pmids\": [\"31658303\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    }\n  ],\n  \"current_model\": \"UCH54 (PF3D7_1117100) is a cysteine-dependent deubiquitinating enzyme in P. falciparum that possesses dual deubiquitinating and deNeddylating activities (the latter absent from its mammalian homologues), associates transiently and substoichiometrically with the P. falciparum 26S proteasome complex as a proteasome-interacting deubiquitinase, and its activities are sensitive to N-ethylmaleimide, indicating dependence on an active-site cysteine residue.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"UCH54 (PF3D7_1117100) is a cysteine-dependent deubiquitinating enzyme of Plasmodium falciparum that was the first deubiquitinase identified in the parasite [#0]. It possesses dual specificity, reacting with both ubiquitin- and Nedd8-based activity-based probes and thereby displaying both deubiquitinating and deNeddylating activity — the latter being absent from its mammalian homologues [#0, #2]. Its reactivity is abolished by N-ethylmaleimide, indicating dependence on an active-site cysteine [#0]. UCH54 associates transiently and substoichiometrically with the P. falciparum 26S proteasome complex, consistent with a role as a proteasome-interacting deubiquitinase [#1]. Beyond these activity-based and association findings, the specific substrates, structural basis of catalysis, and cellular consequences of UCH54 activity have not been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Whether P. falciparum possesses an active deubiquitinating enzyme was unknown; activity-based profiling identified UCH54 as the first such enzyme and revealed an unexpected dual deubiquitinating/deNeddylating activity not seen in mammalian homologues.\",\n      \"evidence\": \"Activity-based protein profiling of schizont lysate with ubiquitin and Nedd8 electrophilic probes, mass spectrometry identification, and N-ethylmaleimide inhibition to confirm active-site cysteine dependence\",\n      \"pmids\": [\"16925553\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No functional substrate identified in the parasite\", \"Catalytic cysteine not pinpointed by mutagenesis\", \"Cellular role and phenotype of loss not tested\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"How UCH54 relates to the parasite proteolytic machinery was unresolved; quantitative proteomics of purified proteasomes placed UCH54 as a transient, substoichiometric proteasome-associated deubiquitinase.\",\n      \"evidence\": \"Affinity purification of functional 26S proteasome complexes from P. falciparum with in situ crosslinking and NSAF-based quantitative mass spectrometry\",\n      \"pmids\": [\"26639022\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Association shown by co-purification only, no functional mutagenesis\", \"Direct binding interface with the proteasome not mapped\", \"Substoichiometric recovery leaves the fraction of proteasome-bound UCH54 undefined\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Whether the dual ubiquitin/Nedd8 reactivity was reproducible and how parasite deNeddylation differs from the host was open; chemical probe profiling confirmed UCH54 reacts with both probe types within a broader distinction between parasite and human deNeddylation enzymes.\",\n      \"evidence\": \"Functional ubiquitin- and Nedd8-based activity-based probes with parasite transgenics and drug assays\",\n      \"pmids\": [\"31658303\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"UCH54 was not functionally dissected independently in this study, which focused on a sibling enzyme\", \"Relative contribution of UCH54 versus other enzymes to parasite deNeddylation not quantified\", \"No structural or kinetic characterization\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The endogenous substrates, catalytic residue identity, structural basis of dual ubiquitin/Nedd8 specificity, and the physiological consequence of UCH54 activity or its proteasome association remain unknown.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No physiological substrate defined\", \"No genetic knockout/knockdown phenotype reported\", \"No structure or catalytic mutant characterized\"],\n      \"attribution\": [{\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0004843\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"GO:0019784\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"GO:0004197\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"GO:0006511\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0045116\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"complexes\": [\"26S proteasome (transient, substoichiometric association)\"],\n    \"partners\": [\"P. falciparum 26S proteasome complex\"],\n    \"other_free_text\": [\n      \"First deubiquitinating enzyme identified in P. falciparum by activity-based protein profiling.\",\n      \"Displays dual deubiquitinating and deNeddylating activity, the latter absent from mammalian homologues.\",\n      \"Activity is N-ethylmaleimide-sensitive, indicating dependence on an active-site cysteine.\",\n      \"Homolog of UCH37/proteasome-interacting deubiquitinase; associates transiently and substoichiometrically with the 26S proteasome.\"\n    ]\n  }\n}\n```","audit_flag":null,"strains":[{"strain":"Pf3D7","gene_id":"PF3D7_1117100","name":null,"product":"ubiquitin carboxyl-terminal hydrolase UCH54","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PbANKA","gene_id":"PBANKA_0930900","name":null,"product":"ubiquitin carboxyl-terminal hydrolase UCH54, putative","uniprot_acc":null,"chromosome":null,"start_pos":null},{"strain":"PkH","gene_id":"PKNH_0914800","name":null,"product":"ubiquitin carboxyl-terminal hydrolase UCH54, putative","uniprot_acc":null,"chromosome":null,"start_pos":null}],"gene_symbol":"UCH54","evaluation":null}