{"gene":"TG_293690","gene_symbol":"PRF","run_date":"2026-09-08T14:08:30","timeline":{"discoveries":[{"year":2010,"finding":"Crystal structure of TgPRF revealed a parasite-specific surface motif consisting of an acidic loop followed by a long β-hairpin. Structure-based mutagenesis showed that TLR11 recognition of this acidic loop is responsible for most IL-12 secretion in peritoneal macrophages. Deletion of both the acidic loop and β-hairpin completely abrogates IL-12 secretion. Insertion of the T. gondii acidic loop and β-hairpin into yeast profilin is sufficient to generate TLR11-dependent signaling, establishing this motif as the key molecular pattern recognized by TLR11.","method":"X-ray crystallography, structure-based mutagenesis, IL-12 secretion assay in peritoneal macrophages, chimeric profilin insertion into yeast profilin","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure combined with site-directed mutagenesis and functional rescue (chimeric insertion) in a single rigorous study with multiple orthogonal methods","pmids":["20851125"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2010,"finding":"Unlike vertebrate profilins, TgPRF slows nucleotide exchange on monomeric rabbit actin and binds rabbit actin weakly. The putative TgPRF actin-binding surface includes the β-hairpin and diverges widely from the actin-binding surfaces of vertebrate profilins.","method":"In vitro nucleotide exchange assay, actin-binding assay, structural comparison","journal":"Journal of molecular biology","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro biochemical assay from a single study; actin-binding divergence is structurally and biochemically supported but not further validated by mutagenesis of the actin-binding surface","pmids":["20851125"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"TgPRF (TgP) stimulates NLRP3 inflammasome activation in THP-1 macrophages, leading to IL-1β production and secretion. Treatment with the NLRP3 inhibitor MCC950 significantly reduced NLRP3 and IL-1β at both transcriptional and protein levels. Western blot showed increased NLRP3 protein and both pro- and mature IL-1β after TgP treatment. TgP also significantly increased TLR5 expression, but not TLR2, 4, or 9.","method":"NLRP3 inhibitor (MCC950) treatment, western blot, ELISA, qRT-PCR in THP-1 cell line","journal":"Microbial pathogenesis","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological inhibition combined with protein-level and transcriptional readouts in a single study, two orthogonal methods (western blot + ELISA)","pmids":["37080500"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"current_model":"TgPRF is a profilin that promotes actin-based gliding motility; its parasite-specific acidic loop and β-hairpin motif are recognized by TLR11 to drive IL-12 secretion, it weakly binds mammalian actin and slows nucleotide exchange unlike vertebrate profilins, and it additionally activates the NLRP3 inflammasome to induce IL-1β production in macrophages."},"narrative":{"mechanistic_narrative":"TgPRF is a Toxoplasma gondii profilin that combines a cytoskeletal actin-regulatory function with a potent role as a pathogen-associated molecular pattern driving innate immune activation [PMID:20851125]. Its crystal structure reveals a parasite-specific surface motif — an acidic loop followed by a long β-hairpin — that is recognized by TLR11 to trigger IL-12 secretion in macrophages; deleting both elements abolishes IL-12 induction, and grafting them onto yeast profilin is sufficient to confer TLR11-dependent signaling, establishing this motif as the key molecular pattern [PMID:20851125]. Biochemically, TgPRF diverges from vertebrate profilins: it binds monomeric actin weakly and slows rather than accelerates nucleotide exchange, with a putative actin-binding surface that includes the β-hairpin [PMID:20851125]. Beyond TLR11, TgPRF activates the NLRP3 inflammasome in macrophages, driving processing and secretion of IL-1β in a manner blocked by the NLRP3 inhibitor MCC950, and it upregulates TLR5 expression [PMID:37080500].","teleology":[{"year":2010,"claim":"Defining the structural basis by which the host innate immune system detects a parasite profilin, this work identified an acidic loop/β-hairpin motif as the molecular pattern recognized by TLR11 to drive IL-12 secretion.","evidence":"X-ray crystallography with structure-based mutagenesis, IL-12 secretion assays in peritoneal macrophages, and gain-of-function chimeric insertion into yeast profilin","pmids":["20851125"],"confidence":"High","gaps":["Does not resolve the TLR11 binding interface at atomic resolution","IL-12 shown in mouse peritoneal macrophages; relevance to human TLR biology not addressed here"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2010,"claim":"To test whether TgPRF retains canonical profilin actin-regulatory activity, biochemical assays showed it behaves unlike vertebrate profilins — binding actin weakly and slowing nucleotide exchange — indicating a divergent actin-binding surface.","evidence":"In vitro nucleotide exchange and actin-binding assays with monomeric rabbit actin plus structural comparison","pmids":["20851125"],"confidence":"Medium","gaps":["Actin-binding surface not confirmed by mutagenesis","Assays used rabbit actin, not parasite actin; physiological relevance to gliding motility not directly tested"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"claim":"Extending TgPRF's immunostimulatory role beyond TLR11/IL-12, this work showed it also engages the NLRP3 inflammasome to drive IL-1β production, revealing a second innate immune axis.","evidence":"NLRP3 inhibitor (MCC950) treatment with western blot, ELISA, and qRT-PCR in THP-1 macrophages","pmids":["37080500"],"confidence":"Medium","gaps":["Mechanism linking TgPRF to NLRP3 activation not defined","TLR5 upregulation observed but its causal role in inflammasome activation not established","Single cell-line study without genetic knockout confirmation"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":null,"claim":"How TgPRF's actin-regulatory activity mechanistically contributes to parasite gliding motility, and how its immune-detection functions integrate in vivo, remain unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No direct in vivo link between TgPRF actin binding and gliding motility in the corpus","Physical TgPRF–TLR11 and TgPRF–NLRP3 interactions not structurally defined"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":["TLR11","ACTIN","NLRP3","TLR5"],"other_free_text":["Parasite-specific acidic loop followed by a long β-hairpin surface motif recognized by TLR11 (idx 0)","Grafting the T. gondii acidic loop and β-hairpin onto yeast profilin confers TLR11-dependent signaling (idx 0)","Slows nucleotide exchange on monomeric actin, opposite to vertebrate profilins (idx 1)","NLRP3 inflammasome activation is MCC950-sensitive and drives pro- and mature IL-1β production (idx 2)"]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"20851125","id":"PMC_20851125","title":"Structure-based analysis of Toxoplasma gondii profilin: a parasite-specific motif is required for recognition by Toll-like receptor 11.","date":"2010","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/20851125","citation_count":49,"is_preprint":false},{"pmid":"30858341","id":"PMC_30858341","title":"Transcriptional Analysis Shows a Robust Host Response to Toxoplasma gondii during Early and Late Chronic Infection in Both Male and Female Mice.","date":"2019","source":"Infection and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/30858341","citation_count":22,"is_preprint":false},{"pmid":"37080500","id":"PMC_37080500","title":"Toxoplasma gondii profilin induces NLRP3 activation and IL-1β production/secretion in THP-1 cells.","date":"2023","source":"Microbial pathogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/37080500","citation_count":12,"is_preprint":false},{"pmid":"26080521","id":"PMC_26080521","title":"[Prokaryotic Expression and Immunoreactivity Analysis on Profilin of Toxoplasma gondii].","date":"2015","source":"Zhongguo ji sheng chong xue yu ji sheng chong bing za zhi = Chinese journal of parasitology & parasitic diseases","url":"https://pubmed.ncbi.nlm.nih.gov/26080521","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":4430,"output_tokens":1034,"usd":0.0144,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":5930,"output_tokens":2128,"usd":0.041425,"stage2_stop_reason":"end_turn"},"total_usd":0.055825,"stage1_batch_id":"msgbatch_015xmQKDRqnTh9anE4m7LiD6","stage2_batch_id":"msgbatch_01JLpkFTVhoQBNgqHCKFrVVU","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2010,\n      \"finding\": \"Crystal structure of TgPRF revealed a parasite-specific surface motif consisting of an acidic loop followed by a long β-hairpin. Structure-based mutagenesis showed that TLR11 recognition of this acidic loop is responsible for most IL-12 secretion in peritoneal macrophages. Deletion of both the acidic loop and β-hairpin completely abrogates IL-12 secretion. Insertion of the T. gondii acidic loop and β-hairpin into yeast profilin is sufficient to generate TLR11-dependent signaling, establishing this motif as the key molecular pattern recognized by TLR11.\",\n      \"method\": \"X-ray crystallography, structure-based mutagenesis, IL-12 secretion assay in peritoneal macrophages, chimeric profilin insertion into yeast profilin\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure combined with site-directed mutagenesis and functional rescue (chimeric insertion) in a single rigorous study with multiple orthogonal methods\",\n      \"pmids\": [\"20851125\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Unlike vertebrate profilins, TgPRF slows nucleotide exchange on monomeric rabbit actin and binds rabbit actin weakly. The putative TgPRF actin-binding surface includes the β-hairpin and diverges widely from the actin-binding surfaces of vertebrate profilins.\",\n      \"method\": \"In vitro nucleotide exchange assay, actin-binding assay, structural comparison\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro biochemical assay from a single study; actin-binding divergence is structurally and biochemically supported but not further validated by mutagenesis of the actin-binding surface\",\n      \"pmids\": [\"20851125\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TgPRF (TgP) stimulates NLRP3 inflammasome activation in THP-1 macrophages, leading to IL-1β production and secretion. Treatment with the NLRP3 inhibitor MCC950 significantly reduced NLRP3 and IL-1β at both transcriptional and protein levels. Western blot showed increased NLRP3 protein and both pro- and mature IL-1β after TgP treatment. TgP also significantly increased TLR5 expression, but not TLR2, 4, or 9.\",\n      \"method\": \"NLRP3 inhibitor (MCC950) treatment, western blot, ELISA, qRT-PCR in THP-1 cell line\",\n      \"journal\": \"Microbial pathogenesis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological inhibition combined with protein-level and transcriptional readouts in a single study, two orthogonal methods (western blot + ELISA)\",\n      \"pmids\": [\"37080500\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}\n      ]\n    }\n  ],\n  \"current_model\": \"TgPRF is a profilin that promotes actin-based gliding motility; its parasite-specific acidic loop and β-hairpin motif are recognized by TLR11 to drive IL-12 secretion, it weakly binds mammalian actin and slows nucleotide exchange unlike vertebrate profilins, and it additionally activates the NLRP3 inflammasome to induce IL-1β production in macrophages.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"TgPRF is a Toxoplasma gondii profilin that combines a cytoskeletal actin-regulatory function with a potent role as a pathogen-associated molecular pattern driving innate immune activation [#0, #1]. Its crystal structure reveals a parasite-specific surface motif — an acidic loop followed by a long β-hairpin — that is recognized by TLR11 to trigger IL-12 secretion in macrophages; deleting both elements abolishes IL-12 induction, and grafting them onto yeast profilin is sufficient to confer TLR11-dependent signaling, establishing this motif as the key molecular pattern [#0]. Biochemically, TgPRF diverges from vertebrate profilins: it binds monomeric actin weakly and slows rather than accelerates nucleotide exchange, with a putative actin-binding surface that includes the β-hairpin [#1]. Beyond TLR11, TgPRF activates the NLRP3 inflammasome in macrophages, driving processing and secretion of IL-1β in a manner blocked by the NLRP3 inhibitor MCC950, and it upregulates TLR5 expression [#2].\",\n  \"teleology\": [\n    {\n      \"year\": 2010,\n      \"claim\": \"Defining the structural basis by which the host innate immune system detects a parasite profilin, this work identified an acidic loop/β-hairpin motif as the molecular pattern recognized by TLR11 to drive IL-12 secretion.\",\n      \"evidence\": \"X-ray crystallography with structure-based mutagenesis, IL-12 secretion assays in peritoneal macrophages, and gain-of-function chimeric insertion into yeast profilin\",\n      \"pmids\": [\"20851125\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not resolve the TLR11 binding interface at atomic resolution\", \"IL-12 shown in mouse peritoneal macrophages; relevance to human TLR biology not addressed here\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"To test whether TgPRF retains canonical profilin actin-regulatory activity, biochemical assays showed it behaves unlike vertebrate profilins — binding actin weakly and slowing nucleotide exchange — indicating a divergent actin-binding surface.\",\n      \"evidence\": \"In vitro nucleotide exchange and actin-binding assays with monomeric rabbit actin plus structural comparison\",\n      \"pmids\": [\"20851125\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Actin-binding surface not confirmed by mutagenesis\", \"Assays used rabbit actin, not parasite actin; physiological relevance to gliding motility not directly tested\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Extending TgPRF's immunostimulatory role beyond TLR11/IL-12, this work showed it also engages the NLRP3 inflammasome to drive IL-1β production, revealing a second innate immune axis.\",\n      \"evidence\": \"NLRP3 inhibitor (MCC950) treatment with western blot, ELISA, and qRT-PCR in THP-1 macrophages\",\n      \"pmids\": [\"37080500\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking TgPRF to NLRP3 activation not defined\", \"TLR5 upregulation observed but its causal role in inflammasome activation not established\", \"Single cell-line study without genetic knockout confirmation\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How TgPRF's actin-regulatory activity mechanistically contributes to parasite gliding motility, and how its immune-detection functions integrate in vivo, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No direct in vivo link between TgPRF actin binding and gliding motility in the corpus\", \"Physical TgPRF–TLR11 and TgPRF–NLRP3 interactions not structurally defined\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003785\", \"supporting_discovery_ids\": [1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0035325\", \"supporting_discovery_ids\": [0], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"GO:0032727\", \"supporting_discovery_ids\": [0], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0032611\", \"supporting_discovery_ids\": [2], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0072559\", \"supporting_discovery_ids\": [2], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"TLR11\", \"actin\", \"NLRP3\", \"TLR5\"],\n    \"other_free_text\": [\n      \"Parasite-specific acidic loop followed by a long β-hairpin surface motif recognized by TLR11 (idx 0)\",\n      \"Grafting the T. gondii acidic loop and β-hairpin onto yeast profilin confers TLR11-dependent signaling (idx 0)\",\n      \"Slows nucleotide exchange on monomeric actin, opposite to vertebrate profilins (idx 1)\",\n      \"NLRP3 inflammasome activation is MCC950-sensitive and drives pro- and mature IL-1β production (idx 2)\"\n    ]\n  },\n  \"strain_conflicts\": []\n}\n```","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_293690","name":"PRF","product":"profilin PRF","uniprot_acc":"A0A125YS70","chromosome":"TGME49_chrIa","start_pos":510053},{"strain":"GT1","gene_id":"TGGT1_293690","name":null,"product":"profilin PRF","uniprot_acc":null,"chromosome":"TGGT1_chrIa","start_pos":496750},{"strain":"RH88","gene_id":"TGRH88_018990","name":null,"product":"profilin PRF","uniprot_acc":null,"chromosome":"CM023081","start_pos":516916},{"strain":"VEG","gene_id":"TGVEG_293690","name":null,"product":"profilin PRF","uniprot_acc":"A0A125YS71","chromosome":"TGVEG_chrIa","start_pos":520372}]}