{"gene":"TG_294400","gene_symbol":"RON2L1","run_date":"2026-09-08T14:08:30","timeline":{"discoveries":[{"year":2014,"finding":"Disruption of the AMA1 gene results in upregulation of AMA1 and RON2 homologues (including RON2L1) that cooperate to support residual host cell invasion, demonstrating molecular plasticity and redundancy among AMA-RON pairs at the moving junction.","method":"Reverse genetics (AMA1 gene disruption), invasion assays","journal":"Nature Communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean genetic knockout with defined invasion phenotype and upregulation of paralogs, single lab","pmids":["24934579"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2015,"finding":"TgRON2L1 forms a high-affinity, functional complex with TgAMA4 at the parasite-host cell interface; high-resolution crystal structures of TgAMA4 in apo and TgRON2L1-bound forms, complemented with alanine scanning mutagenesis, reveal an unexpected assembly mechanism: TgAMA4 lacks both the deep surface groove and the key surface loop that govern RON2 ligand binding selectivity in canonical AMA-RON2 complexes.","method":"Co-crystallization, X-ray crystallography, alanine scanning mutagenesis, binding affinity assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — atomic-resolution crystal structures of the complex combined with mutagenesis in a single rigorous study","pmids":["26712012"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2015,"finding":"TgAMA4 clusters phylogenetically with Plasmodium MAEBL proteins and is expressed in sporozoites, while its partner TgRON2L1 is co-evolved to interact with it, indicating a sporozoite-stage-specific AMA-RON pair divergent from the canonical tachyzoite AMA1-RON2 machinery.","method":"Phylogenetic analysis, expression profiling, structural and biochemical characterization","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — phylogenetics combined with structural/biochemical validation, single lab","pmids":["26712012"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"In bradyzoites, the moving junction relies on AMA4 and RON2L1 (rather than the tachyzoite AMA1-RON2 pair); functional characterization showed AMA4 is required for cyst burden during chronic infection but dispensable for the acute phase, placing the AMA4-RON2L1 complex as a key molecular component of the bradyzoite moving junction.","method":"Genetic disruption of AMA4, cyst burden assays, immunization experiments, functional characterization","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean loss-of-function genetics with defined stage-specific phenotype (cyst burden) and vaccine validation, single rigorous study with multiple orthogonal approaches","pmids":["36693095"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"Immunization with the AMA4-RON2L1 complex more selectively targets the chronic form of toxoplasmosis (bradyzoite stage) compared to AMA1-RON2, validating the AMA4-RON2L1 pair as a stage-specific vaccine candidate.","method":"Mouse immunization and challenge experiments, cyst burden quantification","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo vaccination/challenge with quantitative readout, single lab","pmids":["36693095"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"current_model":"TgRON2L1 is a rhoptry neck protein that forms a high-affinity functional complex with TgAMA4 at the moving junction during host cell invasion; this AMA4-RON2L1 pair is structurally and mechanistically distinct from the canonical AMA1-RON2 complex (lacking the conserved groove/loop binding architecture), is expressed in sporozoites and bradyzoites rather than tachyzoites, is required for cyst burden during chronic infection, and can be upregulated as a redundant invasion module when AMA1-RON2 function is disrupted."},"narrative":{"mechanistic_narrative":"TgRON2L1 is a Toxoplasma gondii rhoptry neck protein that functions as a stage-specific component of the moving junction during host cell invasion, forming a high-affinity functional complex with the AMA-family protein TgAMA4 at the parasite-host interface [PMID:26712012, PMID:36693095]. High-resolution crystal structures of the TgAMA4-RON2L1 complex reveal an assembly mechanism distinct from the canonical AMA1-RON2 pair: TgAMA4 lacks both the deep surface groove and the key surface loop that govern RON2 ligand-binding selectivity, defining a structurally divergent AMA-RON module [PMID:26712012]. Rather than operating in tachyzoites, the TgAMA4-RON2L1 pair is deployed in sporozoites and bradyzoites, and is required for cyst burden during chronic infection while being dispensable for the acute phase [PMID:26712012, PMID:36693095]. The complex also serves as a redundant invasion module, upregulated to support residual host cell invasion when AMA1 is disrupted [PMID:24934579], and immunization with the assembled complex selectively targets the chronic bradyzoite stage [PMID:36693095].","teleology":[{"year":2014,"claim":"Whether the AMA1-RON2 moving-junction machinery is uniquely essential was unknown; disrupting AMA1 revealed that paralogous AMA-RON pairs including RON2L1 are upregulated to sustain residual invasion, establishing functional plasticity and redundancy at the moving junction.","evidence":"Reverse genetics (AMA1 gene disruption) with invasion assays in T. gondii","pmids":["24934579"],"confidence":"Medium","gaps":["Does not define the direct binding partner or structural basis of the RON2L1 complex","Does not establish which life stage naturally uses RON2L1"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2015,"claim":"It was unclear whether RON2L1 engaged an AMA partner and by what architecture; co-crystallization with TgAMA4 and mutagenesis showed a high-affinity complex assembled without the canonical groove and loop that define AMA1-RON2 selectivity, establishing a mechanistically distinct AMA-RON pairing.","evidence":"Co-crystallization, X-ray crystallography, alanine scanning mutagenesis and binding assays in T. gondii","pmids":["26712012"],"confidence":"High","gaps":["Structure does not establish the in vivo invasion role of the complex","Cellular localization dynamics at the junction not resolved by the structure"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2015,"claim":"The developmental context of the AMA4-RON2L1 pair was undefined; phylogenetic and expression analysis placed TgAMA4 with Plasmodium MAEBL proteins and in sporozoites, framing RON2L1 as part of a co-evolved, stage-specific alternative to the tachyzoite AMA1-RON2 machinery.","evidence":"Phylogenetic analysis and expression profiling with structural/biochemical characterization in T. gondii","pmids":["26712012"],"confidence":"Medium","gaps":["Correlative expression does not prove functional requirement in sporozoites","Does not test the pair's role in bradyzoites"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"claim":"Whether the AMA4-RON2L1 complex is functionally required in vivo was unknown; genetic disruption of AMA4 showed it is needed for cyst burden during chronic infection but dispensable for acute infection, establishing the complex as the bradyzoite-stage moving-junction module.","evidence":"Genetic disruption of AMA4 with cyst burden assays and functional characterization in T. gondii","pmids":["36693095"],"confidence":"High","gaps":["Direct RON2L1 loss-of-function phenotype not separately reported here","Mechanism of stage-specific expression switching not defined"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"claim":"Whether the stage-specific complex could be exploited therapeutically was open; immunization with the AMA4-RON2L1 complex selectively targeted the chronic bradyzoite form compared to AMA1-RON2, validating it as a stage-specific vaccine target.","evidence":"Mouse immunization and challenge experiments with cyst burden quantification in T. gondii","pmids":["36693095"],"confidence":"Medium","gaps":["Durability and mechanism of protective immunity not defined","Single-lab in vivo model"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":null,"claim":"How RON2L1 is trafficked to and inserted into the host cell membrane at the moving junction, and the molecular basis of its stage-restricted deployment, remain uncharacterized in the available corpus.","evidence":"","pmids":[],"confidence":"Low","gaps":["No mechanism for stage-specific transcriptional/translational control","Membrane insertion and rhoptry secretion dynamics of RON2L1 not defined"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["TgAMA4-RON2L1 moving junction complex"],"partners":["TGAMA4"],"other_free_text":["Structurally distinct from the canonical AMA1-RON2 complex; TgAMA4 lacks the RON2-binding groove and surface loop [#1].","Expressed/functional in sporozoite and bradyzoite stages rather than tachyzoites [#2, #3].","Required for cyst burden during chronic infection [#3]; validated as a stage-specific vaccine target [#4].","Upregulated as a redundant invasion module when AMA1-RON2 is disrupted [#0]."]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"24934579","id":"PMC_24934579","title":"Plasticity and redundancy among AMA-RON pairs ensure host cell entry of Toxoplasma parasites.","date":"2014","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/24934579","citation_count":128,"is_preprint":false},{"pmid":"26712012","id":"PMC_26712012","title":"Dissecting the interface between apicomplexan parasite and host cell: Insights from a divergent AMA-RON2 pair.","date":"2015","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/26712012","citation_count":29,"is_preprint":false},{"pmid":"36693095","id":"PMC_36693095","title":"Invasion of Toxoplasma gondii bradyzoites: Molecular dissection of the moving junction proteins and effective vaccination targets.","date":"2023","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/36693095","citation_count":24,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":3893,"output_tokens":1374,"usd":0.016144,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":6461,"output_tokens":2505,"usd":0.047465,"stage2_stop_reason":"end_turn"},"total_usd":0.063609,"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\": 2014,\n      \"finding\": \"Disruption of the AMA1 gene results in upregulation of AMA1 and RON2 homologues (including RON2L1) that cooperate to support residual host cell invasion, demonstrating molecular plasticity and redundancy among AMA-RON pairs at the moving junction.\",\n      \"method\": \"Reverse genetics (AMA1 gene disruption), invasion assays\",\n      \"journal\": \"Nature Communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic knockout with defined invasion phenotype and upregulation of paralogs, single lab\",\n      \"pmids\": [\"24934579\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"TgRON2L1 forms a high-affinity, functional complex with TgAMA4 at the parasite-host cell interface; high-resolution crystal structures of TgAMA4 in apo and TgRON2L1-bound forms, complemented with alanine scanning mutagenesis, reveal an unexpected assembly mechanism: TgAMA4 lacks both the deep surface groove and the key surface loop that govern RON2 ligand binding selectivity in canonical AMA-RON2 complexes.\",\n      \"method\": \"Co-crystallization, X-ray crystallography, alanine scanning mutagenesis, binding affinity assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — atomic-resolution crystal structures of the complex combined with mutagenesis in a single rigorous study\",\n      \"pmids\": [\"26712012\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"TgAMA4 clusters phylogenetically with Plasmodium MAEBL proteins and is expressed in sporozoites, while its partner TgRON2L1 is co-evolved to interact with it, indicating a sporozoite-stage-specific AMA-RON pair divergent from the canonical tachyzoite AMA1-RON2 machinery.\",\n      \"method\": \"Phylogenetic analysis, expression profiling, structural and biochemical characterization\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — phylogenetics combined with structural/biochemical validation, single lab\",\n      \"pmids\": [\"26712012\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In bradyzoites, the moving junction relies on AMA4 and RON2L1 (rather than the tachyzoite AMA1-RON2 pair); functional characterization showed AMA4 is required for cyst burden during chronic infection but dispensable for the acute phase, placing the AMA4-RON2L1 complex as a key molecular component of the bradyzoite moving junction.\",\n      \"method\": \"Genetic disruption of AMA4, cyst burden assays, immunization experiments, functional characterization\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean loss-of-function genetics with defined stage-specific phenotype (cyst burden) and vaccine validation, single rigorous study with multiple orthogonal approaches\",\n      \"pmids\": [\"36693095\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Immunization with the AMA4-RON2L1 complex more selectively targets the chronic form of toxoplasmosis (bradyzoite stage) compared to AMA1-RON2, validating the AMA4-RON2L1 pair as a stage-specific vaccine candidate.\",\n      \"method\": \"Mouse immunization and challenge experiments, cyst burden quantification\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo vaccination/challenge with quantitative readout, single lab\",\n      \"pmids\": [\"36693095\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"TgRON2L1 is a rhoptry neck protein that forms a high-affinity functional complex with TgAMA4 at the moving junction during host cell invasion; this AMA4-RON2L1 pair is structurally and mechanistically distinct from the canonical AMA1-RON2 complex (lacking the conserved groove/loop binding architecture), is expressed in sporozoites and bradyzoites rather than tachyzoites, is required for cyst burden during chronic infection, and can be upregulated as a redundant invasion module when AMA1-RON2 function is disrupted.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"TgRON2L1 is a Toxoplasma gondii rhoptry neck protein that functions as a stage-specific component of the moving junction during host cell invasion, forming a high-affinity functional complex with the AMA-family protein TgAMA4 at the parasite-host interface [#1, #3]. High-resolution crystal structures of the TgAMA4-RON2L1 complex reveal an assembly mechanism distinct from the canonical AMA1-RON2 pair: TgAMA4 lacks both the deep surface groove and the key surface loop that govern RON2 ligand-binding selectivity, defining a structurally divergent AMA-RON module [#1]. Rather than operating in tachyzoites, the TgAMA4-RON2L1 pair is deployed in sporozoites and bradyzoites, and is required for cyst burden during chronic infection while being dispensable for the acute phase [#2, #3]. The complex also serves as a redundant invasion module, upregulated to support residual host cell invasion when AMA1 is disrupted [#0], and immunization with the assembled complex selectively targets the chronic bradyzoite stage [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2014,\n      \"claim\": \"Whether the AMA1-RON2 moving-junction machinery is uniquely essential was unknown; disrupting AMA1 revealed that paralogous AMA-RON pairs including RON2L1 are upregulated to sustain residual invasion, establishing functional plasticity and redundancy at the moving junction.\",\n      \"evidence\": \"Reverse genetics (AMA1 gene disruption) with invasion assays in T. gondii\",\n      \"pmids\": [\"24934579\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not define the direct binding partner or structural basis of the RON2L1 complex\", \"Does not establish which life stage naturally uses RON2L1\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"It was unclear whether RON2L1 engaged an AMA partner and by what architecture; co-crystallization with TgAMA4 and mutagenesis showed a high-affinity complex assembled without the canonical groove and loop that define AMA1-RON2 selectivity, establishing a mechanistically distinct AMA-RON pairing.\",\n      \"evidence\": \"Co-crystallization, X-ray crystallography, alanine scanning mutagenesis and binding assays in T. gondii\",\n      \"pmids\": [\"26712012\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure does not establish the in vivo invasion role of the complex\", \"Cellular localization dynamics at the junction not resolved by the structure\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"The developmental context of the AMA4-RON2L1 pair was undefined; phylogenetic and expression analysis placed TgAMA4 with Plasmodium MAEBL proteins and in sporozoites, framing RON2L1 as part of a co-evolved, stage-specific alternative to the tachyzoite AMA1-RON2 machinery.\",\n      \"evidence\": \"Phylogenetic analysis and expression profiling with structural/biochemical characterization in T. gondii\",\n      \"pmids\": [\"26712012\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Correlative expression does not prove functional requirement in sporozoites\", \"Does not test the pair's role in bradyzoites\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Whether the AMA4-RON2L1 complex is functionally required in vivo was unknown; genetic disruption of AMA4 showed it is needed for cyst burden during chronic infection but dispensable for acute infection, establishing the complex as the bradyzoite-stage moving-junction module.\",\n      \"evidence\": \"Genetic disruption of AMA4 with cyst burden assays and functional characterization in T. gondii\",\n      \"pmids\": [\"36693095\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct RON2L1 loss-of-function phenotype not separately reported here\", \"Mechanism of stage-specific expression switching not defined\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Whether the stage-specific complex could be exploited therapeutically was open; immunization with the AMA4-RON2L1 complex selectively targeted the chronic bradyzoite form compared to AMA1-RON2, validating it as a stage-specific vaccine target.\",\n      \"evidence\": \"Mouse immunization and challenge experiments with cyst burden quantification in T. gondii\",\n      \"pmids\": [\"36693095\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Durability and mechanism of protective immunity not defined\", \"Single-lab in vivo model\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How RON2L1 is trafficked to and inserted into the host cell membrane at the moving junction, and the molecular basis of its stage-restricted deployment, remain uncharacterized in the available corpus.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No mechanism for stage-specific transcriptional/translational control\", \"Membrane insertion and rhoptry secretion dynamics of RON2L1 not defined\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005515\", \"supporting_discovery_ids\": [1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0020002\", \"supporting_discovery_ids\": [1, 3], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0044409\", \"supporting_discovery_ids\": [0, 3], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [\"TgAMA4-RON2L1 moving junction complex\"],\n    \"partners\": [\"TgAMA4\"],\n    \"other_free_text\": [\n      \"Structurally distinct from the canonical AMA1-RON2 complex; TgAMA4 lacks the RON2-binding groove and surface loop [#1].\",\n      \"Expressed/functional in sporozoite and bradyzoite stages rather than tachyzoites [#2, #3].\",\n      \"Required for cyst burden during chronic infection [#3]; validated as a stage-specific vaccine target [#4].\",\n      \"Upregulated as a redundant invasion module when AMA1-RON2 is disrupted [#0].\"\n    ]\n  },\n  \"strain_conflicts\": []\n}\n```","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_294400","name":"RON2L1","product":"rhoptry neck protein RON2L1","uniprot_acc":"A0A125YVA5","chromosome":"TGME49_chrIa","start_pos":879001},{"strain":"GT1","gene_id":"TGGT1_294400","name":null,"product":"hypothetical protein","uniprot_acc":null,"chromosome":"TGGT1_chrIa","start_pos":864813},{"strain":"RH88","gene_id":"TGRH88_019490","name":null,"product":"unspecified product","uniprot_acc":null,"chromosome":"CM023081","start_pos":884993},{"strain":"VEG","gene_id":"TGVEG_294400","name":null,"product":"cytoadherence-linked asexual protein","uniprot_acc":"B6KQU6","chromosome":"TGVEG_chrIa","start_pos":888332}]}