{"gene":"TG_319940","gene_symbol":"SNAP29","run_date":"2026-09-08T15:15:13","timeline":{"discoveries":[{"year":2022,"finding":"TgSNAP29 (a Qbc SNARE protein) is required to maintain the apicoplast in T. gondii; its depletion disrupted TgATG8 localization at the apicoplast, suggesting TgATG8 is translocated to the apicoplast via vesicles in a SNARE-dependent manner.","method":"Inducible auxin-inducible degron (AID)-based depletion of TgSNAP29 with subsequent monitoring of TgATG8 localization","journal":"Autophagy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean inducible knockdown with defined cellular phenotype (loss of ATG8 localization at apicoplast), single lab, two orthogonal readouts (apicoplast maintenance and ATG8 localization)","pmids":["36095096"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"The only SNAP25-family protein in T. gondii has a SNAP29-like molecular structure and is involved in vesicular fusion at the apicoplast, but does NOT mediate vesicular fusion at the plasma membrane (that role is fulfilled by an unconventional SNARE complex of TgStx1, TgStx20, and TgStx21).","method":"Functional characterization of SNARE complex components by genetic and cell biological approaches, including plasma membrane exocytosis assays and localization studies","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional assignment of TgSNAP29-like protein to apicoplast vesicular fusion (not plasma membrane), single lab, supported by identification of alternative complex handling plasma membrane fusion","pmids":["36972314"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"current_model":"TgSNAP29, the sole SNAP25-family SNARE protein in Toxoplasma gondii with a SNAP29-like structure, functions specifically at the apicoplast where it mediates SNARE-dependent vesicular fusion required for TgATG8 translocation and apicoplast biogenesis/maintenance, but does not mediate exocytosis at the plasma membrane."},"narrative":{"mechanistic_narrative":"SNAP29 (TgSNAP29), the sole SNAP25-family SNARE protein in Toxoplasma gondii, adopts a SNAP29-like structure and functions as a Qbc SNARE mediating SNARE-dependent vesicular fusion at the apicoplast, where it is required for apicoplast biogenesis and maintenance [PMID:36095096, PMID:36972314]. Its depletion disrupts localization of TgATG8 at the apicoplast, indicating that TgATG8 is delivered to the organelle via vesicles in a SNARE-dependent manner [PMID:36095096]. TgSNAP29 acts specifically at the apicoplast and does not mediate vesicular fusion at the plasma membrane, a role instead fulfilled by an unconventional SNARE complex of TgStx1, TgStx20, and TgStx21 [PMID:36972314]. Beyond this apicoplast fusion role, no further mechanistic detail on TgSNAP29 has been characterized in the available corpus.","teleology":[{"year":2022,"claim":"Whether apicoplast maintenance and TgATG8 delivery depend on membrane fusion machinery was unknown; showing that depleting a Qbc SNARE disrupts both established a SNARE-dependent vesicular route for ATG8 translocation to the apicoplast.","evidence":"Auxin-inducible degron depletion of TgSNAP29 in T. gondii with monitoring of apicoplast maintenance and TgATG8 localization","pmids":["36095096"],"confidence":"Medium","gaps":["The direct SNARE partners of TgSNAP29 at the apicoplast are not identified","The vesicular source and cargo composition delivering TgATG8 are not defined","Whether TgATG8 is a direct fusion cargo or an indirect consequence of disrupted fusion is unresolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"claim":"Whether the single SNAP25-family protein acts generally in secretion or at a specific compartment was unknown; functional characterization assigned it to apicoplast vesicular fusion and excluded a role at the plasma membrane, which is instead served by a distinct syntaxin complex.","evidence":"Genetic and cell biological characterization of SNARE components including plasma membrane exocytosis assays and localization studies in T. gondii","pmids":["36972314"],"confidence":"Medium","gaps":["The molecular structure of TgSNAP29 is inferred as SNAP29-like rather than experimentally solved","The full apicoplast SNARE complex composition is not defined","How TgSNAP29 is targeted specifically to the apicoplast and excluded from the plasma membrane is unknown"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":null,"claim":"The direct SNARE partners, structural basis, and vesicle-targeting mechanism of TgSNAP29 at the apicoplast remain undefined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No apicoplast SNARE complex partners have been identified for TgSNAP29","No experimental structure exists","The mechanism restricting TgSNAP29 function to the apicoplast is uncharacterized"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["Apicoplast SNARE complex (partners undefined)"],"partners":["TGATG8 (LOCALIZATION DEPENDENT ON TGSNAP29)"],"other_free_text":["Sole SNAP25-family SNARE in T. gondii, with a SNAP29-like structure and Qbc SNARE classification","Required for apicoplast biogenesis/maintenance and SNARE-dependent TgATG8 translocation to the apicoplast","Does not mediate plasma membrane fusion; that role is served by an unconventional TgStx1/TgStx20/TgStx21 complex"]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"36095096","id":"PMC_36095096","title":"Apicoplast biogenesis mediated by ATG8 requires the ATG12-ATG5-ATG16L and SNAP29 complexes in Toxoplasma gondii.","date":"2022","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/36095096","citation_count":24,"is_preprint":false},{"pmid":"36972314","id":"PMC_36972314","title":"An unconventional SNARE complex mediates exocytosis at the plasma membrane and vesicular fusion at the apical annuli in Toxoplasma gondii.","date":"2023","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/36972314","citation_count":11,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":3570,"output_tokens":676,"usd":0.010425,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":5385,"output_tokens":1748,"usd":0.035312,"stage2_stop_reason":"end_turn"},"total_usd":0.045737,"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\": 2022,\n      \"finding\": \"TgSNAP29 (a Qbc SNARE protein) is required to maintain the apicoplast in T. gondii; its depletion disrupted TgATG8 localization at the apicoplast, suggesting TgATG8 is translocated to the apicoplast via vesicles in a SNARE-dependent manner.\",\n      \"method\": \"Inducible auxin-inducible degron (AID)-based depletion of TgSNAP29 with subsequent monitoring of TgATG8 localization\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean inducible knockdown with defined cellular phenotype (loss of ATG8 localization at apicoplast), single lab, two orthogonal readouts (apicoplast maintenance and ATG8 localization)\",\n      \"pmids\": [\"36095096\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"The only SNAP25-family protein in T. gondii has a SNAP29-like molecular structure and is involved in vesicular fusion at the apicoplast, but does NOT mediate vesicular fusion at the plasma membrane (that role is fulfilled by an unconventional SNARE complex of TgStx1, TgStx20, and TgStx21).\",\n      \"method\": \"Functional characterization of SNARE complex components by genetic and cell biological approaches, including plasma membrane exocytosis assays and localization studies\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional assignment of TgSNAP29-like protein to apicoplast vesicular fusion (not plasma membrane), single lab, supported by identification of alternative complex handling plasma membrane fusion\",\n      \"pmids\": [\"36972314\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    }\n  ],\n  \"current_model\": \"TgSNAP29, the sole SNAP25-family SNARE protein in Toxoplasma gondii with a SNAP29-like structure, functions specifically at the apicoplast where it mediates SNARE-dependent vesicular fusion required for TgATG8 translocation and apicoplast biogenesis/maintenance, but does not mediate exocytosis at the plasma membrane.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SNAP29 (TgSNAP29), the sole SNAP25-family SNARE protein in Toxoplasma gondii, adopts a SNAP29-like structure and functions as a Qbc SNARE mediating SNARE-dependent vesicular fusion at the apicoplast, where it is required for apicoplast biogenesis and maintenance [#0, #1]. Its depletion disrupts localization of TgATG8 at the apicoplast, indicating that TgATG8 is delivered to the organelle via vesicles in a SNARE-dependent manner [#0]. TgSNAP29 acts specifically at the apicoplast and does not mediate vesicular fusion at the plasma membrane, a role instead fulfilled by an unconventional SNARE complex of TgStx1, TgStx20, and TgStx21 [#1]. Beyond this apicoplast fusion role, no further mechanistic detail on TgSNAP29 has been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2022,\n      \"claim\": \"Whether apicoplast maintenance and TgATG8 delivery depend on membrane fusion machinery was unknown; showing that depleting a Qbc SNARE disrupts both established a SNARE-dependent vesicular route for ATG8 translocation to the apicoplast.\",\n      \"evidence\": \"Auxin-inducible degron depletion of TgSNAP29 in T. gondii with monitoring of apicoplast maintenance and TgATG8 localization\",\n      \"pmids\": [\"36095096\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"The direct SNARE partners of TgSNAP29 at the apicoplast are not identified\",\n        \"The vesicular source and cargo composition delivering TgATG8 are not defined\",\n        \"Whether TgATG8 is a direct fusion cargo or an indirect consequence of disrupted fusion is unresolved\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Whether the single SNAP25-family protein acts generally in secretion or at a specific compartment was unknown; functional characterization assigned it to apicoplast vesicular fusion and excluded a role at the plasma membrane, which is instead served by a distinct syntaxin complex.\",\n      \"evidence\": \"Genetic and cell biological characterization of SNARE components including plasma membrane exocytosis assays and localization studies in T. gondii\",\n      \"pmids\": [\"36972314\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"The molecular structure of TgSNAP29 is inferred as SNAP29-like rather than experimentally solved\",\n        \"The full apicoplast SNARE complex composition is not defined\",\n        \"How TgSNAP29 is targeted specifically to the apicoplast and excluded from the plasma membrane is unknown\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The direct SNARE partners, structural basis, and vesicle-targeting mechanism of TgSNAP29 at the apicoplast remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No apicoplast SNARE complex partners have been identified for TgSNAP29\",\n        \"No experimental structure exists\",\n        \"The mechanism restricting TgSNAP29 function to the apicoplast is uncharacterized\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005484\", \"supporting_discovery_ids\": [0, 1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0009508\", \"supporting_discovery_ids\": [0, 1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0006906\", \"supporting_discovery_ids\": [0, 1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [\"Apicoplast SNARE complex (partners undefined)\"],\n    \"partners\": [\"TgATG8 (localization dependent on TgSNAP29)\"],\n    \"other_free_text\": [\n      \"Sole SNAP25-family SNARE in T. gondii, with a SNAP29-like structure and Qbc SNARE classification\",\n      \"Required for apicoplast biogenesis/maintenance and SNARE-dependent TgATG8 translocation to the apicoplast\",\n      \"Does not mediate plasma membrane fusion; that role is served by an unconventional TgStx1/TgStx20/TgStx21 complex\"\n    ]\n  },\n  \"strain_conflicts\": []\n}","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_319940","name":"SNAP29","product":"synaptosomal-associated protein 29","uniprot_acc":"A0A125YMR7","chromosome":"TGME49_chrIV","start_pos":641463},{"strain":"GT1","gene_id":"TGGT1_319940","name":null,"product":"hypothetical protein","uniprot_acc":null,"chromosome":"TGGT1_chrIV","start_pos":586239},{"strain":"RH88","gene_id":"TGRH88_007240","name":null,"product":"unspecified product","uniprot_acc":null,"chromosome":"CM023085","start_pos":652617},{"strain":"VEG","gene_id":"TGVEG_319940","name":null,"product":"putative SNARE domain protein","uniprot_acc":"V4Z2T5","chromosome":"TGVEG_chrIV","start_pos":641225}]}