{"gene":"TG_307770","gene_symbol":"PANK1","run_date":"2026-09-08T15:15:13","timeline":{"discoveries":[{"year":2021,"finding":"TgPanK1 and TgPanK2 form a single heteromeric complex that possesses pantothenate kinase (PanK) activity, representing the first example of a heteromeric PanK complex in nature; both subunits are essential for T. gondii proliferation specifically due to their PanK activity.","method":"Co-immunoprecipitation/pulldown to demonstrate complex formation; biochemical PanK activity assays; genetic loss-of-function (knockdown/knockout) with proliferation as phenotypic readout","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — biochemical activity assay combined with complex formation (Co-IP) and genetic essentiality validation, multiple orthogonal methods in a single rigorous study","pmids":["34324601"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2022,"finding":"CoA synthesis (including the pantothenate kinase step) is essential for T. gondii tachyzoites because the parasite cannot salvage CoA or CoA pathway intermediates; pantothenate synthesis (upstream of PanK) is only partially active in tachyzoites but is crucial for establishing chronic (bradyzoite) infection.","method":"Genetic disruption of pathway enzymes combined with biochemical and metabolomic analyses of CoA and pantothenate levels across life-cycle stages","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic, biochemical, and metabolomic approaches used in combination, replicated across acute and chronic infection stages","pmids":["35039477"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"current_model":"TgPanK1 forms an obligate heteromeric complex with TgPanK2 (the first such heteromeric pantothenate kinase described) to catalyse the first step of coenzyme A biosynthesis from pantothenate; both subunits are individually essential for parasite proliferation, and the overall CoA biosynthetic pathway is indispensable in tachyzoites due to the parasite's inability to salvage CoA or pathway intermediates."},"narrative":{"mechanistic_narrative":"PANK1 (TgPanK1) catalyses the first, committed step of coenzyme A (CoA) biosynthesis from pantothenate in Toxoplasma gondii, functioning not as a standalone enzyme but as one subunit of an obligate heteromeric pantothenate kinase complex with TgPanK2 — the first heteromeric PanK described in nature [PMID:34324601]. Both subunits are individually essential for tachyzoite proliferation specifically through their PanK activity [PMID:34324601]. This requirement reflects the indispensability of the CoA biosynthetic pathway in the parasite, which cannot salvage CoA or its pathway intermediates, so de novo synthesis through the PanK step is metabolically essential in acute-stage tachyzoites [PMID:35039477]. Beyond its role in this heteromeric complex and the essentiality of the CoA pathway it initiates [PMID:34324601, PMID:35039477], no further mechanistic detail (structure, regulation, or catalytic mechanism) has been characterized in the available corpus.","teleology":[{"year":2021,"claim":"Establishing that TgPanK1 does not act alone but forms an obligate heteromeric PanK complex with TgPanK2 answered how the parasite organizes the first step of CoA synthesis and revealed a previously unknown enzyme architecture.","evidence":"Co-immunoprecipitation/pulldown for complex formation, biochemical PanK activity assays, and genetic knockdown/knockout with proliferation readout in T. gondii","pmids":["34324601"],"confidence":"High","gaps":["No structural model of the heteromeric complex or definition of which subunit contributes the catalytic site","Stoichiometry and assembly mechanism of the complex not resolved","Regulation of complex activity not characterized"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2022,"claim":"Determining that T. gondii cannot salvage CoA or its intermediates explained why the PanK step is essential and placed the enzyme within a pathway whose essentiality is stage-dependent.","evidence":"Genetic disruption of pathway enzymes with biochemical and metabolomic profiling of CoA and pantothenate across acute and chronic infection stages","pmids":["35039477"],"confidence":"High","gaps":["Contribution of PANK1 specifically to bradyzoite/chronic-stage metabolism not isolated from the broader pathway","Mechanism of the parasite's inability to salvage CoA not defined at the transporter level"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":null,"claim":"The catalytic mechanism, structure, and regulatory control of the TgPanK1/TgPanK2 heteromeric complex remain unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No structural characterization of the heteromeric complex","No mapping of active-site residues or substrate-binding determinants across subunits","No data on regulation of PanK activity in response to CoA/pantothenate levels"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["Heteromeric pantothenate kinase complex (TgPanK1–TgPanK2)"],"partners":["TGPANK2"],"other_free_text":["TgPanK1–TgPanK2 is the first heteromeric pantothenate kinase complex described in nature [#0].","Both subunits are individually essential for T. gondii tachyzoite proliferation via their PanK activity [#0].","CoA biosynthesis is essential in tachyzoites because the parasite cannot salvage CoA or pathway intermediates [#1]."]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"35039477","id":"PMC_35039477","title":"Pantothenate biosynthesis is critical for chronic infection by the neurotropic parasite Toxoplasma gondii.","date":"2022","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/35039477","citation_count":22,"is_preprint":false},{"pmid":"34324601","id":"PMC_34324601","title":"A novel heteromeric pantothenate kinase complex in apicomplexan parasites.","date":"2021","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/34324601","citation_count":16,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":3206,"output_tokens":652,"usd":0.009699,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":5374,"output_tokens":1586,"usd":0.03326,"stage2_stop_reason":"end_turn"},"total_usd":0.042959,"stage1_batch_id":"msgbatch_01S6GjoYQm8LTPUsdhASdqag","stage2_batch_id":"msgbatch_01VX63RTMdBJqsG6gQMqoCjz","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2021,\n      \"finding\": \"TgPanK1 and TgPanK2 form a single heteromeric complex that possesses pantothenate kinase (PanK) activity, representing the first example of a heteromeric PanK complex in nature; both subunits are essential for T. gondii proliferation specifically due to their PanK activity.\",\n      \"method\": \"Co-immunoprecipitation/pulldown to demonstrate complex formation; biochemical PanK activity assays; genetic loss-of-function (knockdown/knockout) with proliferation as phenotypic readout\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — biochemical activity assay combined with complex formation (Co-IP) and genetic essentiality validation, multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"34324601\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CoA synthesis (including the pantothenate kinase step) is essential for T. gondii tachyzoites because the parasite cannot salvage CoA or CoA pathway intermediates; pantothenate synthesis (upstream of PanK) is only partially active in tachyzoites but is crucial for establishing chronic (bradyzoite) infection.\",\n      \"method\": \"Genetic disruption of pathway enzymes combined with biochemical and metabolomic analyses of CoA and pantothenate levels across life-cycle stages\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic, biochemical, and metabolomic approaches used in combination, replicated across acute and chronic infection stages\",\n      \"pmids\": [\"35039477\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    }\n  ],\n  \"current_model\": \"TgPanK1 forms an obligate heteromeric complex with TgPanK2 (the first such heteromeric pantothenate kinase described) to catalyse the first step of coenzyme A biosynthesis from pantothenate; both subunits are individually essential for parasite proliferation, and the overall CoA biosynthetic pathway is indispensable in tachyzoites due to the parasite's inability to salvage CoA or pathway intermediates.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PANK1 (TgPanK1) catalyses the first, committed step of coenzyme A (CoA) biosynthesis from pantothenate in Toxoplasma gondii, functioning not as a standalone enzyme but as one subunit of an obligate heteromeric pantothenate kinase complex with TgPanK2 — the first heteromeric PanK described in nature [#0]. Both subunits are individually essential for tachyzoite proliferation specifically through their PanK activity [#0]. This requirement reflects the indispensability of the CoA biosynthetic pathway in the parasite, which cannot salvage CoA or its pathway intermediates, so de novo synthesis through the PanK step is metabolically essential in acute-stage tachyzoites [#1]. Beyond its role in this heteromeric complex and the essentiality of the CoA pathway it initiates [#0, #1], no further mechanistic detail (structure, regulation, or catalytic mechanism) has been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2021,\n      \"claim\": \"Establishing that TgPanK1 does not act alone but forms an obligate heteromeric PanK complex with TgPanK2 answered how the parasite organizes the first step of CoA synthesis and revealed a previously unknown enzyme architecture.\",\n      \"evidence\": \"Co-immunoprecipitation/pulldown for complex formation, biochemical PanK activity assays, and genetic knockdown/knockout with proliferation readout in T. gondii\",\n      \"pmids\": [\"34324601\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No structural model of the heteromeric complex or definition of which subunit contributes the catalytic site\",\n        \"Stoichiometry and assembly mechanism of the complex not resolved\",\n        \"Regulation of complex activity not characterized\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Determining that T. gondii cannot salvage CoA or its intermediates explained why the PanK step is essential and placed the enzyme within a pathway whose essentiality is stage-dependent.\",\n      \"evidence\": \"Genetic disruption of pathway enzymes with biochemical and metabolomic profiling of CoA and pantothenate across acute and chronic infection stages\",\n      \"pmids\": [\"35039477\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Contribution of PANK1 specifically to bradyzoite/chronic-stage metabolism not isolated from the broader pathway\",\n        \"Mechanism of the parasite's inability to salvage CoA not defined at the transporter level\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The catalytic mechanism, structure, and regulatory control of the TgPanK1/TgPanK2 heteromeric complex remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No structural characterization of the heteromeric complex\",\n        \"No mapping of active-site residues or substrate-binding determinants across subunits\",\n        \"No data on regulation of PanK activity in response to CoA/pantothenate levels\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0004594\", \"supporting_discovery_ids\": [0], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"GO:0015937\", \"supporting_discovery_ids\": [0, 1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [\"Heteromeric pantothenate kinase complex (TgPanK1–TgPanK2)\"],\n    \"partners\": [\"TgPanK2\"],\n    \"other_free_text\": [\n      \"TgPanK1–TgPanK2 is the first heteromeric pantothenate kinase complex described in nature [#0].\",\n      \"Both subunits are individually essential for T. gondii tachyzoite proliferation via their PanK activity [#0].\",\n      \"CoA biosynthesis is essential in tachyzoites because the parasite cannot salvage CoA or pathway intermediates [#1].\"\n    ]\n  },\n  \"strain_conflicts\": []\n}","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_307770","name":"PANK1","product":"pantothenate kinase 1","uniprot_acc":"S8EU95","chromosome":"TGME49_chrXII","start_pos":388444},{"strain":"GT1","gene_id":"TGGT1_307770","name":null,"product":"fumble protein","uniprot_acc":null,"chromosome":"TGGT1_chrXII","start_pos":335752},{"strain":"RH88","gene_id":"TGRH88_057500","name":null,"product":"fumble protein","uniprot_acc":null,"chromosome":"CM023093","start_pos":380895},{"strain":"VEG","gene_id":"TGVEG_307770","name":null,"product":"fumble protein","uniprot_acc":"A0A125YTW9","chromosome":"TGVEG_chrXII","start_pos":368603}]}