{"gene":"TG_235880","gene_symbol":"MPC1","run_date":"2026-09-08T12:58:24","timeline":{"discoveries":[{"year":2023,"finding":"MPC1 forms a conserved mitochondrial pyruvate carrier (MPC) complex together with MPC2 in T. gondii, and the two subunits functionally complement a yeast mutant deficient in growth on leucine and valine, establishing their conserved role as pyruvate transporters.","method":"Yeast complementation assay, genetic identification of complex subunits","journal":"Microbiology spectrum","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast complementation plus genetic ablation with metabolic readouts in a single study; no in vitro reconstitution or structural validation","pmids":["36920199"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"Genetic ablation of MPC1 (alone or together with MPC2) reduces parasite growth and impairs synthesis of acetyl-CoA from glucose, demonstrated by isotopic labeling, correlating with decreased carbon flux through glycolysis and the TCA cycle; the phenotype mimics deletion of branched-chain ketoacid dehydrogenase (BCKDH), placing MPC at the link between cytosolic glycolysis and mitochondrial TCA cycle.","method":"Conditional/genetic knockout, isotopic glucose metabolic labeling (13C flux analysis), growth assays","journal":"Microbiology spectrum","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic loss-of-function with two orthogonal readouts (growth assay and isotopic metabolic labeling) and epistatic comparison to BCKDH mutant, single lab","pmids":["36920199"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"Disruption of MPC1 exerts only a modest effect on parasite virulence in mice, indicating that the mitochondrion can compensate for loss of cytosolic pyruvate import, consistent with metabolic plasticity.","method":"Mouse infection model with MPC1 knockout parasites","journal":"Microbiology spectrum","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — in vivo virulence assay with knockout parasites, single lab, single method","pmids":["36920199"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"current_model":"T. gondii MPC1 forms a heteromeric mitochondrial pyruvate carrier complex with MPC2 that transports cytosol-derived pyruvate into the mitochondrion, where it serves as the primary source of acetyl-CoA (via BCKDH), thereby coupling glycolysis to the TCA cycle and supporting optimal asexual parasite growth, while being dispensable for virulence due to the parasite's broader metabolic plasticity."},"narrative":{"mechanistic_narrative":"In Toxoplasma gondii, MPC1 is a subunit of the mitochondrial pyruvate carrier that couples cytosolic glycolysis to the mitochondrial TCA cycle by importing pyruvate into the mitochondrion [PMID:36920199]. MPC1 assembles with MPC2 into a heteromeric carrier complex whose transport function is conserved, as both subunits restore growth on leucine and valine in a transport-deficient yeast mutant [PMID:36920199]. Genetic ablation of MPC1 impairs the synthesis of acetyl-CoA from glucose and reduces carbon flux through glycolysis and the TCA cycle, phenocopying loss of branched-chain ketoacid dehydrogenase and thereby placing the carrier at the junction between cytosolic and mitochondrial carbon metabolism, with a corresponding reduction in asexual parasite growth [PMID:36920199]. Despite this metabolic role, MPC1 disruption has only a modest effect on virulence in mice, indicating that the parasite compensates for loss of cytosolic pyruvate import through broader metabolic plasticity [PMID:36920199]. Beyond these findings, no structural model or in vitro reconstitution of the carrier has been characterized in the available corpus.","teleology":[{"year":2023,"claim":"Establishing whether T. gondii possesses a functional pyruvate transporter answered how the parasite might move glycolytic pyruvate into the mitochondrion, identifying MPC1/MPC2 as a conserved carrier complex.","evidence":"Yeast complementation assay and genetic identification of complex subunits in T. gondii","pmids":["36920199"],"confidence":"Medium","gaps":["No in vitro reconstitution demonstrating direct pyruvate transport","No structural model of the MPC1/MPC2 complex","Stoichiometry and assembly of the complex not resolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"claim":"Determining the metabolic consequence of losing the carrier answered where MPC sits in central carbon metabolism, showing it links cytosolic glycolysis to the mitochondrial TCA cycle via acetyl-CoA generation.","evidence":"Conditional/genetic knockout with 13C glucose isotopic flux labeling, growth assays, and epistatic comparison to a BCKDH mutant","pmids":["36920199"],"confidence":"High","gaps":["Alternative pyruvate/carbon sources compensating in the knockout not fully mapped","Direct measurement of pyruvate import rate not performed","Single-lab evidence"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"claim":"Testing MPC1 requirement in vivo answered whether cytosolic pyruvate import is essential for pathogenesis, revealing it is dispensable for virulence and pointing to metabolic redundancy.","evidence":"Mouse infection model comparing MPC1 knockout parasites to wild type","pmids":["36920199"],"confidence":"Medium","gaps":["Compensating pathways sustaining virulence not identified","Single method, single lab","No assessment across life-cycle stages"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":null,"claim":"The molecular basis of pyruvate transport by the MPC1/MPC2 complex and the identity of the compensatory pathways sustaining growth and virulence in its absence remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural or biochemical reconstitution of transport","Compensatory carbon-source pathways uncharacterized","Regulation of carrier expression/activity unknown"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["Mitochondrial pyruvate carrier (MPC) complex (MPC1/MPC2)"],"partners":["MPC2"],"other_free_text":["MPC1/MPC2 functionally complement a yeast mutant deficient in growth on leucine and valine [#0]","MPC1 ablation impairs glucose-derived acetyl-CoA synthesis and phenocopies BCKDH deletion [#1]","MPC1 is dispensable for virulence in mice, consistent with metabolic plasticity [#2]"]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"36920199","id":"PMC_36920199","title":"The Mitochondrial Pyruvate Carrier Coupling Glycolysis and the Tricarboxylic Acid Cycle Is Required for the Asexual Reproduction of Toxoplasma gondii.","date":"2023","source":"Microbiology spectrum","url":"https://pubmed.ncbi.nlm.nih.gov/36920199","citation_count":13,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":3254,"output_tokens":840,"usd":0.011181,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":5671,"output_tokens":1908,"usd":0.038027,"stage2_stop_reason":"end_turn"},"total_usd":0.049208,"stage1_batch_id":"msgbatch_01TEPNZ4MCzJ7xtsNwosiDRk","stage2_batch_id":"msgbatch_01FQShM7n1sfCr4pWTDShmki","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2023,\n      \"finding\": \"MPC1 forms a conserved mitochondrial pyruvate carrier (MPC) complex together with MPC2 in T. gondii, and the two subunits functionally complement a yeast mutant deficient in growth on leucine and valine, establishing their conserved role as pyruvate transporters.\",\n      \"method\": \"Yeast complementation assay, genetic identification of complex subunits\",\n      \"journal\": \"Microbiology spectrum\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast complementation plus genetic ablation with metabolic readouts in a single study; no in vitro reconstitution or structural validation\",\n      \"pmids\": [\"36920199\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Genetic ablation of MPC1 (alone or together with MPC2) reduces parasite growth and impairs synthesis of acetyl-CoA from glucose, demonstrated by isotopic labeling, correlating with decreased carbon flux through glycolysis and the TCA cycle; the phenotype mimics deletion of branched-chain ketoacid dehydrogenase (BCKDH), placing MPC at the link between cytosolic glycolysis and mitochondrial TCA cycle.\",\n      \"method\": \"Conditional/genetic knockout, isotopic glucose metabolic labeling (13C flux analysis), growth assays\",\n      \"journal\": \"Microbiology spectrum\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic loss-of-function with two orthogonal readouts (growth assay and isotopic metabolic labeling) and epistatic comparison to BCKDH mutant, single lab\",\n      \"pmids\": [\"36920199\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Disruption of MPC1 exerts only a modest effect on parasite virulence in mice, indicating that the mitochondrion can compensate for loss of cytosolic pyruvate import, consistent with metabolic plasticity.\",\n      \"method\": \"Mouse infection model with MPC1 knockout parasites\",\n      \"journal\": \"Microbiology spectrum\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — in vivo virulence assay with knockout parasites, single lab, single method\",\n      \"pmids\": [\"36920199\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    }\n  ],\n  \"current_model\": \"T. gondii MPC1 forms a heteromeric mitochondrial pyruvate carrier complex with MPC2 that transports cytosol-derived pyruvate into the mitochondrion, where it serves as the primary source of acetyl-CoA (via BCKDH), thereby coupling glycolysis to the TCA cycle and supporting optimal asexual parasite growth, while being dispensable for virulence due to the parasite's broader metabolic plasticity.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"In Toxoplasma gondii, MPC1 is a subunit of the mitochondrial pyruvate carrier that couples cytosolic glycolysis to the mitochondrial TCA cycle by importing pyruvate into the mitochondrion [#0, #1]. MPC1 assembles with MPC2 into a heteromeric carrier complex whose transport function is conserved, as both subunits restore growth on leucine and valine in a transport-deficient yeast mutant [#0]. Genetic ablation of MPC1 impairs the synthesis of acetyl-CoA from glucose and reduces carbon flux through glycolysis and the TCA cycle, phenocopying loss of branched-chain ketoacid dehydrogenase and thereby placing the carrier at the junction between cytosolic and mitochondrial carbon metabolism, with a corresponding reduction in asexual parasite growth [#1]. Despite this metabolic role, MPC1 disruption has only a modest effect on virulence in mice, indicating that the parasite compensates for loss of cytosolic pyruvate import through broader metabolic plasticity [#2]. Beyond these findings, no structural model or in vitro reconstitution of the carrier has been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2023,\n      \"claim\": \"Establishing whether T. gondii possesses a functional pyruvate transporter answered how the parasite might move glycolytic pyruvate into the mitochondrion, identifying MPC1/MPC2 as a conserved carrier complex.\",\n      \"evidence\": \"Yeast complementation assay and genetic identification of complex subunits in T. gondii\",\n      \"pmids\": [\"36920199\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No in vitro reconstitution demonstrating direct pyruvate transport\", \"No structural model of the MPC1/MPC2 complex\", \"Stoichiometry and assembly of the complex not resolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Determining the metabolic consequence of losing the carrier answered where MPC sits in central carbon metabolism, showing it links cytosolic glycolysis to the mitochondrial TCA cycle via acetyl-CoA generation.\",\n      \"evidence\": \"Conditional/genetic knockout with 13C glucose isotopic flux labeling, growth assays, and epistatic comparison to a BCKDH mutant\",\n      \"pmids\": [\"36920199\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Alternative pyruvate/carbon sources compensating in the knockout not fully mapped\", \"Direct measurement of pyruvate import rate not performed\", \"Single-lab evidence\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Testing MPC1 requirement in vivo answered whether cytosolic pyruvate import is essential for pathogenesis, revealing it is dispensable for virulence and pointing to metabolic redundancy.\",\n      \"evidence\": \"Mouse infection model comparing MPC1 knockout parasites to wild type\",\n      \"pmids\": [\"36920199\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Compensating pathways sustaining virulence not identified\", \"Single method, single lab\", \"No assessment across life-cycle stages\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The molecular basis of pyruvate transport by the MPC1/MPC2 complex and the identity of the compensatory pathways sustaining growth and virulence in its absence remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural or biochemical reconstitution of transport\", \"Compensatory carbon-source pathways uncharacterized\", \"Regulation of carrier expression/activity unknown\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0050833\", \"supporting_discovery_ids\": [0, 1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005743\", \"supporting_discovery_ids\": [0, 1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0006090\", \"supporting_discovery_ids\": [1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [\"Mitochondrial pyruvate carrier (MPC) complex (MPC1/MPC2)\"],\n    \"partners\": [\"MPC2\"],\n    \"other_free_text\": [\n      \"MPC1/MPC2 functionally complement a yeast mutant deficient in growth on leucine and valine [#0]\",\n      \"MPC1 ablation impairs glucose-derived acetyl-CoA synthesis and phenocopies BCKDH deletion [#1]\",\n      \"MPC1 is dispensable for virulence in mice, consistent with metabolic plasticity [#2]\"\n    ]\n  },\n  \"strain_conflicts\": []\n}","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_235880","name":"MPC1","product":"mitochondrial pyruvate carrier protein 1","uniprot_acc":"A0A125YT77","chromosome":"TGME49_chrX","start_pos":5114628},{"strain":"GT1","gene_id":"TGGT1_235880","name":null,"product":"brain protein 44 family protein","uniprot_acc":null,"chromosome":"TGGT1_chrX","start_pos":5003314},{"strain":"RH88","gene_id":"TGRH88_041690","name":null,"product":"brain protein 44 family protein","uniprot_acc":null,"chromosome":"CM023091","start_pos":2423158},{"strain":"VEG","gene_id":"TGVEG_235880","name":null,"product":"brain protein 44 family protein","uniprot_acc":"B9Q757","chromosome":"TGVEG_chrX","start_pos":5036445}]}