{"gene":"TG_310440","gene_symbol":"MORN1","run_date":"2026-09-08T18:09:55+00:00","timeline":{"discoveries":[{"year":2006,"finding":"MORN1 localizes to ring structures at the apical and posterior ends of the inner membrane complex (IMC) and to the centrocone (a specialized nuclear structure organizing the mitotic spindle). Time-lapse imaging showed these structures are highly dynamic during division. Overexpression of MORN1 caused specific defects in nuclear segregation and daughter cell formation. Biochemically, recombinant MORN1 is soluble in bacteria, but in the parasite it associates with the cytoskeleton after detergent extraction, consistent with a role as a linker between membrane regions and the cytoskeleton.","method":"YFP fusion screen, time-lapse live imaging, overexpression with phenotypic readout, detergent fractionation/cytoskeletal association assay","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal localization by live imaging, overexpression phenotype, and biochemical fractionation in a single study with multiple orthogonal methods","pmids":["16684814"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2008,"finding":"MORN1 localizes to the posterior ring of the IMC of multiple daughters during T. gondii endopolygeny, Eimeria schizogony, and P. falciparum schizogony, and P. falciparum MORN1 protein peaks in late schizogony. In sexual stages, MORN1 is organized as a ring-like structure where microgametes bud from the microgametocyte, and is present near flagellar basal bodies and mitochondrion in mature microgametes, indicating a conserved role in IMC assembly across asexual and sexual development.","method":"Immunolocalization (antibody reactivity), expression analysis across developmental stages in T. gondii, Eimeria spp., and P. falciparum","journal":"Eukaryotic cell","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — consistent immunolocalization across multiple species and stages, single lab, no functional perturbation","pmids":["18310354"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""},{"species":"Eimeria","strain":""},{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"finding":"Conditional ablation of MORN1 in T. gondii results in failure to assemble the basal complex (none of the known basal complex components localize correctly), formation of double- to multi-headed 'Janus' parasites with two complete apical complexes but no basal complex, and failure to efficiently constrict and divide the apicoplast. Cell cycle progression (mother cytoskeleton disassembly, repeated budding) continues despite these defects. Deletion of a single MORN domain abrogated function, and the linker between MORN domains 6 and 7 was identified as critical, defining MORN1 as essential for basal complex assembly and apicoplast segregation.","method":"Conditional null mutant (inducible knockdown), immunofluorescence for basal complex markers, domain-deletion analysis","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional genetic null mutant with multiple orthogonal phenotypic readouts and domain-deletion structure-function analysis, independently replicated by a second lab (PMID:20140195)","pmids":["20808817"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2010,"finding":"Knockout of TgMORN1 (ΔTgMORN1) using Cre-LoxP grossly disrupted the structure of the basal complex and caused cytokinesis defects. ΔTgMORN1 parasites showed significant growth impairment in vitro and greatly attenuated virulence in mice, establishing that TgMORN1 is required for maintaining structural integrity of the parasite posterior end and that cytoskeleton integrity is essential for virulence.","method":"Cre-LoxP knockout, in vitro growth assay, mouse virulence model","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic knockout with multiple phenotypic readouts (structure, growth, virulence), replicated findings align with PMID:20808817","pmids":["20140195"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2012,"finding":"Subcellular fractionation combined with affinity purification of the MORN1 complex identified the protein composition of the basal complex. Two new basal complex components were identified, one uniquely associating with the basal complex only in mature parasites. MORN1 was confirmed to act as a scaffolding protein for basal complex assembly.","method":"Subcellular fractionation, affinity purification (MORN1 co-purification/pulldown), mass spectrometry","journal":"Cytoskeleton (Hoboken, N.J.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — affinity purification with MS, single lab, functional context supported by prior knockouts","pmids":["23027733"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2016,"finding":"Yeast two-hybrid screen using TgMORN1 as bait identified the HAD phosphatase HAD2a as a direct interaction partner. HAD2a co-localizes with MORN1 at the basal complex during contraction and is required for basal complex assembly and cytokinesis, suggesting that MORN1-associated phosphorylation regulates basal complex structure and/or contractile function.","method":"Yeast two-hybrid screen with TgMORN1 as bait, co-localization by immunofluorescence, conditional knockout of HAD2a, in vitro phosphatase activity assay","journal":"Cellular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid plus co-localization plus functional knockout, single lab","pmids":["26840427"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2020,"finding":"Crystal structures, SAXS, and EM of MORN1 from Trypanosoma brucei, Toxoplasma gondii, and Plasmodium falciparum revealed that MORN repeats are protein-protein interaction modules (not lipid-binding modules as previously assumed). All three ortholog structures dimerize via their C-termini in an antiparallel configuration, and dimers can adopt extended or V-shaped quaternary structures depending on specific interface residues. No evidence for membrane or lipid vesicle binding was found, though individual phospholipid interactions were detected.","method":"Macromolecular X-ray crystallography, SAXS, electron microscopy, in vitro lipid-binding assays","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 1 / Moderate — high-resolution structures for TgMORN1 and two orthologs with functional validation of interaction properties, single study with multiple orthogonal structural methods","pmids":["33296386"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""},{"species":"Trypanosoma brucei","strain":""},{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"finding":"Reciprocal proximity-based biotinylation (BioID) proteomics using MORN1 as a landmark identified four architecturally distinct basal complex (BC) subcomplexes with dynamic composition. MORN1, together with BCC4, was found to form a 'rubber band' that sequesters the basal end of the assembling daughter cytoskeleton, constituting the essential cell-division function of the BC.","method":"Reciprocal BioID proximity biotinylation, conditional expression disruption, spatiotemporal immunofluorescence analysis","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal proximity proteomics plus functional disruption of multiple components, single lab with multiple orthogonal approaches","pmids":["35941170"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2026,"finding":"SPR-MS target identification and AI-driven analysis identified TgMORN1 as the highest-scoring target of Licochalcone A. RNAi silencing of TgMORN1 attenuated the anti-proliferative effect of Lico A. Western blotting, NanoDSF, and SPR supported direct binding between Lico A and TgMORN1, with residues S168 and D203 implicated in modulating TgMORN1 thermal stability.","method":"SPR-MS target identification, RNAi knockdown, NanoDSF thermal stability assay, SPR binding assay, Western blotting","journal":"Biomolecules","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal biophysical binding methods plus RNAi functional confirmation, single lab","pmids":["41897346"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"current_model":"TgMORN1 is a cytoskeletal scaffolding protein that forms antiparallel C-terminal dimers (and higher-order oligomers) via its MORN repeat modules (which are protein-protein interaction domains, not lipid-binding modules), localizes dynamically to the posterior and apical rings of the inner membrane complex and to the centrocone during cell division, is essential for basal complex assembly, and together with BCC4 forms a 'rubber band' that sequesters the basal end of the assembling daughter cytoskeleton — loss of MORN1 causes failure of basal complex assembly, defective apicoplast segregation, cytokinesis arrest producing multi-headed conjoined daughters, and severely attenuated virulence; MORN1 also directly recruits the HAD phosphatase HAD2a to regulate basal complex contraction, and is a direct binding target of the small molecule Licochalcone A at residues S168 and D203."},"narrative":{"mechanistic_narrative":"MORN1 is a cytoskeletal scaffolding protein of apicomplexan and related parasites that organizes assembly of the basal complex and coordinates daughter-cell cytokinesis during parasite division [PMID:16684814, PMID:20808817]. It localizes dynamically to ring structures at the apical and posterior ends of the inner membrane complex (IMC) and to the centrocone, and associates with the cytoskeleton after detergent extraction, consistent with a linker between membrane regions and the cytoskeleton [PMID:16684814]; this posterior-ring localization is conserved across asexual and sexual stages of T. gondii, Eimeria, and P. falciparum [PMID:18310354]. Structurally, MORN repeats function as protein-protein interaction modules rather than lipid-binding domains, and MORN1 orthologs from T. gondii, T. brucei, and P. falciparum dimerize via their C-termini in an antiparallel configuration to form extended or V-shaped oligomers [PMID:33296386]. As the scaffold for basal complex assembly, MORN1 recruits its constituent proteins, and together with BCC4 it forms a contractile 'rubber band' that sequesters the basal end of the assembling daughter cytoskeleton [PMID:23027733, PMID:35941170]; it also directly binds the HAD phosphatase HAD2a to regulate basal complex contraction [PMID:26840427]. Loss of MORN1 abolishes basal complex assembly, produces multi-headed conjoined 'Janus' parasites with defective apicoplast segregation, and severely attenuates growth and virulence [PMID:20808817, PMID:20140195]. TgMORN1 is a direct binding target of the small molecule Licochalcone A, with residues S168 and D203 implicated in modulating its thermal stability [PMID:41897346].","teleology":[{"year":2006,"claim":"Establishing where MORN1 acts addressed whether a candidate cytoskeletal protein participates in parasite division: it localizes to dynamic apical/posterior IMC rings and the centrocone and links membrane regions to the cytoskeleton.","evidence":"YFP fusion, time-lapse live imaging, overexpression phenotyping, and detergent fractionation in T. gondii","pmids":["16684814"],"confidence":"High","gaps":["Molecular partners not yet identified","Overexpression phenotype does not establish endogenous loss-of-function role"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2008,"claim":"Testing whether MORN1 function is conserved across parasites and life stages showed posterior-ring localization during T. gondii endopolygeny, Eimeria and P. falciparum schizogony, and during sexual microgamete budding, indicating a broadly conserved role in IMC assembly.","evidence":"Immunolocalization and staged expression analysis across T. gondii, Eimeria, and P. falciparum","pmids":["18310354"],"confidence":"Medium","gaps":["No functional perturbation in any species","Antibody-based localization only, single lab"],"attribution":[{"species":"Toxoplasma gondii","strain":""},{"species":"Eimeria","strain":""},{"species":"Plasmodium falciparum","strain":""}]},{"year":2010,"claim":"Genetic ablation determined whether MORN1 is required for division, establishing it as essential for basal complex assembly, apicoplast segregation, and cytokinesis, with loss producing multi-headed 'Janus' parasites and attenuated virulence.","evidence":"Conditional null and Cre-LoxP knockouts with basal complex marker immunofluorescence, domain-deletion analysis, in vitro growth, and mouse virulence assays in T. gondii (two independent labs)","pmids":["20808817","20140195"],"confidence":"High","gaps":["Mechanism of apicoplast segregation coupling not resolved","How MORN1 recruits downstream basal complex components not defined"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2012,"claim":"Defining the composition of the MORN1 complex addressed what MORN1 scaffolds, cataloguing basal complex components including one recruited only in mature parasites and confirming MORN1 as the assembly scaffold.","evidence":"Subcellular fractionation, MORN1 affinity purification, and mass spectrometry in T. gondii","pmids":["23027733"],"confidence":"Medium","gaps":["Direct versus indirect interactions not distinguished","Single lab, no reciprocal validation"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2016,"claim":"Identifying HAD2a as a direct MORN1 partner linked the scaffold to a regulatory enzyme, implicating phosphatase activity in basal complex contraction and cytokinesis.","evidence":"Yeast two-hybrid with TgMORN1 bait, co-localization, conditional HAD2a knockout, and phosphatase activity assay in T. gondii","pmids":["26840427"],"confidence":"Medium","gaps":["Physiological substrates of HAD2a at the basal complex unknown","Mechanistic link from phosphatase activity to contraction not defined"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2020,"claim":"Structural analysis resolved the long-standing assumption about MORN repeats, showing they are protein-protein interaction modules that mediate antiparallel C-terminal dimerization and higher-order oligomers rather than lipid-binding domains.","evidence":"X-ray crystallography, SAXS, EM, and lipid-binding assays on MORN1 from T. gondii, T. brucei, and P. falciparum","pmids":["33296386"],"confidence":"High","gaps":["Physiological relevance of extended versus V-shaped conformers in vivo not established","How oligomer geometry maps to basal complex architecture unresolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""},{"species":"Trypanosoma brucei","strain":""},{"species":"Plasmodium falciparum","strain":""}]},{"year":2022,"claim":"Reciprocal proximity proteomics resolved the basal complex into distinct subcomplexes and identified the MORN1-BCC4 'rubber band' as the essential cell-division function of the structure.","evidence":"Reciprocal BioID, conditional expression disruption, and spatiotemporal immunofluorescence in T. gondii","pmids":["35941170"],"confidence":"High","gaps":["Contractile mechanism of the rubber band not biophysically defined","Regulation of subcomplex assembly dynamics unresolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2026,"claim":"Chemical-genetic target identification established TgMORN1 as a direct binding target of Licochalcone A, offering a small-molecule handle on a cytoskeletal scaffold essential for parasite division.","evidence":"SPR-MS target ID, RNAi knockdown, NanoDSF, SPR, and Western blotting in T. gondii","pmids":["41897346"],"confidence":"Medium","gaps":["Whether S168/D203 binding disrupts MORN1 scaffolding function mechanistically unknown","Single lab, effect on basal complex assembly not directly tested"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":null,"claim":"How MORN1 oligomer geometry and its HAD2a-linked phosphoregulation mechanically drive basal complex contraction to complete cytokinesis remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No biophysical model coupling MORN1 conformation to contractile force","Substrates of HAD2a at the basal complex unidentified","Recruitment hierarchy of basal complex subcomplexes not fully ordered"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["Basal complex (MORN1 scaffold with multiple subcomplexes)","MORN1-BCC4 'rubber band' assembly","MORN1 antiparallel C-terminal homodimers/oligomers"],"partners":["BCC4","HAD2A (HAD PHOSPHATASE)","ADDITIONAL BASAL COMPLEX COMPONENTS IDENTIFIED BY AFFINITY PURIFICATION/BIOID"],"other_free_text":["MORN repeats are protein-protein interaction modules, not lipid-binding domains [#6]","Linker between MORN domains 6 and 7 is critical for function; single MORN domain deletion abrogates function [#2]","Direct binding target of Licochalcone A at residues S168 and D203 [#8]","Conserved posterior-ring localization across asexual and sexual stages of T. gondii, Eimeria, and P. falciparum [#1]"]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"16684814","id":"PMC_16684814","title":"A MORN-repeat protein is a dynamic component of the Toxoplasma gondii cell division apparatus.","date":"2006","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/16684814","citation_count":172,"is_preprint":false},{"pmid":"18310354","id":"PMC_18310354","title":"MORN1 has a conserved role in asexual and sexual development across the apicomplexa.","date":"2008","source":"Eukaryotic cell","url":"https://pubmed.ncbi.nlm.nih.gov/18310354","citation_count":84,"is_preprint":false},{"pmid":"20808817","id":"PMC_20808817","title":"A Toxoplasma MORN1 null mutant undergoes repeated divisions but is defective in basal assembly, apicoplast division and cytokinesis.","date":"2010","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/20808817","citation_count":78,"is_preprint":false},{"pmid":"20140195","id":"PMC_20140195","title":"TgMORN1 is a key organizer for the basal complex of Toxoplasma gondii.","date":"2010","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/20140195","citation_count":77,"is_preprint":false},{"pmid":"35941170","id":"PMC_35941170","title":"Proteomic characterization of the Toxoplasma gondii cytokinesis machinery portrays an expanded hierarchy of its assembly and function.","date":"2022","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/35941170","citation_count":46,"is_preprint":false},{"pmid":"23027733","id":"PMC_23027733","title":"Targeted proteomic dissection of Toxoplasma cytoskeleton sub-compartments using MORN1.","date":"2012","source":"Cytoskeleton (Hoboken, N.J.)","url":"https://pubmed.ncbi.nlm.nih.gov/23027733","citation_count":44,"is_preprint":false},{"pmid":"26840427","id":"PMC_26840427","title":"A MORN1-associated HAD phosphatase in the basal complex is essential for Toxoplasma gondii daughter budding.","date":"2016","source":"Cellular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/26840427","citation_count":24,"is_preprint":false},{"pmid":"25950173","id":"PMC_25950173","title":"Ciprofloxacin Derivatives Affect Parasite Cell Division and Increase the Survival of Mice Infected with Toxoplasma gondii.","date":"2015","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25950173","citation_count":21,"is_preprint":false},{"pmid":"33296386","id":"PMC_33296386","title":"Structures of three MORN repeat proteins and a re-evaluation of the proposed lipid-binding properties of MORN repeats.","date":"2020","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/33296386","citation_count":19,"is_preprint":false},{"pmid":"35573773","id":"PMC_35573773","title":"Toxoplasma gondii's Basal Complex: The Other Apicomplexan Business End Is Multifunctional.","date":"2022","source":"Frontiers in cellular and infection microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/35573773","citation_count":19,"is_preprint":false},{"pmid":"41897346","id":"PMC_41897346","title":"Licochalcone A as a Potential Anti-Toxoplasma Agent: A Target Identification and Pharmacokinetic Study.","date":"2026","source":"Biomolecules","url":"https://pubmed.ncbi.nlm.nih.gov/41897346","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7670,"output_tokens":2947,"usd":0.033607,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8616,"output_tokens":4017,"usd":0.071752,"stage2_stop_reason":"end_turn"},"total_usd":0.0,"stage1_batch_id":"msgbatch_01XFXJD6iZecXyWn9uU5Qom9","stage2_batch_id":"msgbatch_013GToKgs4AKSCRE4yvueviH","note":"batch pricing = 50% of standard","skipped":true},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2006,\n      \"finding\": \"MORN1 localizes to ring structures at the apical and posterior ends of the inner membrane complex (IMC) and to the centrocone (a specialized nuclear structure organizing the mitotic spindle). Time-lapse imaging showed these structures are highly dynamic during division. Overexpression of MORN1 caused specific defects in nuclear segregation and daughter cell formation. Biochemically, recombinant MORN1 is soluble in bacteria, but in the parasite it associates with the cytoskeleton after detergent extraction, consistent with a role as a linker between membrane regions and the cytoskeleton.\",\n      \"method\": \"YFP fusion screen, time-lapse live imaging, overexpression with phenotypic readout, detergent fractionation/cytoskeletal association assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal localization by live imaging, overexpression phenotype, and biochemical fractionation in a single study with multiple orthogonal methods\",\n      \"pmids\": [\"16684814\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"MORN1 localizes to the posterior ring of the IMC of multiple daughters during T. gondii endopolygeny, Eimeria schizogony, and P. falciparum schizogony, and P. falciparum MORN1 protein peaks in late schizogony. In sexual stages, MORN1 is organized as a ring-like structure where microgametes bud from the microgametocyte, and is present near flagellar basal bodies and mitochondrion in mature microgametes, indicating a conserved role in IMC assembly across asexual and sexual development.\",\n      \"method\": \"Immunolocalization (antibody reactivity), expression analysis across developmental stages in T. gondii, Eimeria spp., and P. falciparum\",\n      \"journal\": \"Eukaryotic cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — consistent immunolocalization across multiple species and stages, single lab, no functional perturbation\",\n      \"pmids\": [\"18310354\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"},\n        {\"species\": \"Eimeria\", \"strain\": \"\"},\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Conditional ablation of MORN1 in T. gondii results in failure to assemble the basal complex (none of the known basal complex components localize correctly), formation of double- to multi-headed 'Janus' parasites with two complete apical complexes but no basal complex, and failure to efficiently constrict and divide the apicoplast. Cell cycle progression (mother cytoskeleton disassembly, repeated budding) continues despite these defects. Deletion of a single MORN domain abrogated function, and the linker between MORN domains 6 and 7 was identified as critical, defining MORN1 as essential for basal complex assembly and apicoplast segregation.\",\n      \"method\": \"Conditional null mutant (inducible knockdown), immunofluorescence for basal complex markers, domain-deletion analysis\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional genetic null mutant with multiple orthogonal phenotypic readouts and domain-deletion structure-function analysis, independently replicated by a second lab (PMID:20140195)\",\n      \"pmids\": [\"20808817\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Knockout of TgMORN1 (ΔTgMORN1) using Cre-LoxP grossly disrupted the structure of the basal complex and caused cytokinesis defects. ΔTgMORN1 parasites showed significant growth impairment in vitro and greatly attenuated virulence in mice, establishing that TgMORN1 is required for maintaining structural integrity of the parasite posterior end and that cytoskeleton integrity is essential for virulence.\",\n      \"method\": \"Cre-LoxP knockout, in vitro growth assay, mouse virulence model\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic knockout with multiple phenotypic readouts (structure, growth, virulence), replicated findings align with PMID:20808817\",\n      \"pmids\": [\"20140195\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Subcellular fractionation combined with affinity purification of the MORN1 complex identified the protein composition of the basal complex. Two new basal complex components were identified, one uniquely associating with the basal complex only in mature parasites. MORN1 was confirmed to act as a scaffolding protein for basal complex assembly.\",\n      \"method\": \"Subcellular fractionation, affinity purification (MORN1 co-purification/pulldown), mass spectrometry\",\n      \"journal\": \"Cytoskeleton (Hoboken, N.J.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — affinity purification with MS, single lab, functional context supported by prior knockouts\",\n      \"pmids\": [\"23027733\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Yeast two-hybrid screen using TgMORN1 as bait identified the HAD phosphatase HAD2a as a direct interaction partner. HAD2a co-localizes with MORN1 at the basal complex during contraction and is required for basal complex assembly and cytokinesis, suggesting that MORN1-associated phosphorylation regulates basal complex structure and/or contractile function.\",\n      \"method\": \"Yeast two-hybrid screen with TgMORN1 as bait, co-localization by immunofluorescence, conditional knockout of HAD2a, in vitro phosphatase activity assay\",\n      \"journal\": \"Cellular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid plus co-localization plus functional knockout, single lab\",\n      \"pmids\": [\"26840427\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Crystal structures, SAXS, and EM of MORN1 from Trypanosoma brucei, Toxoplasma gondii, and Plasmodium falciparum revealed that MORN repeats are protein-protein interaction modules (not lipid-binding modules as previously assumed). All three ortholog structures dimerize via their C-termini in an antiparallel configuration, and dimers can adopt extended or V-shaped quaternary structures depending on specific interface residues. No evidence for membrane or lipid vesicle binding was found, though individual phospholipid interactions were detected.\",\n      \"method\": \"Macromolecular X-ray crystallography, SAXS, electron microscopy, in vitro lipid-binding assays\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — high-resolution structures for TgMORN1 and two orthologs with functional validation of interaction properties, single study with multiple orthogonal structural methods\",\n      \"pmids\": [\"33296386\"],\n      \"is_preprint\": false,\n      \"attribution\": [\n        {\"species\": \"Toxoplasma gondii\", \"strain\": \"\"},\n        {\"species\": \"Trypanosoma brucei\", \"strain\": \"\"},\n        {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Reciprocal proximity-based biotinylation (BioID) proteomics using MORN1 as a landmark identified four architecturally distinct basal complex (BC) subcomplexes with dynamic composition. MORN1, together with BCC4, was found to form a 'rubber band' that sequesters the basal end of the assembling daughter cytoskeleton, constituting the essential cell-division function of the BC.\",\n      \"method\": \"Reciprocal BioID proximity biotinylation, conditional expression disruption, spatiotemporal immunofluorescence analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal proximity proteomics plus functional disruption of multiple components, single lab with multiple orthogonal approaches\",\n      \"pmids\": [\"35941170\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"SPR-MS target identification and AI-driven analysis identified TgMORN1 as the highest-scoring target of Licochalcone A. RNAi silencing of TgMORN1 attenuated the anti-proliferative effect of Lico A. Western blotting, NanoDSF, and SPR supported direct binding between Lico A and TgMORN1, with residues S168 and D203 implicated in modulating TgMORN1 thermal stability.\",\n      \"method\": \"SPR-MS target identification, RNAi knockdown, NanoDSF thermal stability assay, SPR binding assay, Western blotting\",\n      \"journal\": \"Biomolecules\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal biophysical binding methods plus RNAi functional confirmation, single lab\",\n      \"pmids\": [\"41897346\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"TgMORN1 is a cytoskeletal scaffolding protein that forms antiparallel C-terminal dimers (and higher-order oligomers) via its MORN repeat modules (which are protein-protein interaction domains, not lipid-binding modules), localizes dynamically to the posterior and apical rings of the inner membrane complex and to the centrocone during cell division, is essential for basal complex assembly, and together with BCC4 forms a 'rubber band' that sequesters the basal end of the assembling daughter cytoskeleton — loss of MORN1 causes failure of basal complex assembly, defective apicoplast segregation, cytokinesis arrest producing multi-headed conjoined daughters, and severely attenuated virulence; MORN1 also directly recruits the HAD phosphatase HAD2a to regulate basal complex contraction, and is a direct binding target of the small molecule Licochalcone A at residues S168 and D203.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"MORN1 is a cytoskeletal scaffolding protein of apicomplexan and related parasites that organizes assembly of the basal complex and coordinates daughter-cell cytokinesis during parasite division [#0, #2]. It localizes dynamically to ring structures at the apical and posterior ends of the inner membrane complex (IMC) and to the centrocone, and associates with the cytoskeleton after detergent extraction, consistent with a linker between membrane regions and the cytoskeleton [#0]; this posterior-ring localization is conserved across asexual and sexual stages of T. gondii, Eimeria, and P. falciparum [#1]. Structurally, MORN repeats function as protein-protein interaction modules rather than lipid-binding domains, and MORN1 orthologs from T. gondii, T. brucei, and P. falciparum dimerize via their C-termini in an antiparallel configuration to form extended or V-shaped oligomers [#6]. As the scaffold for basal complex assembly, MORN1 recruits its constituent proteins, and together with BCC4 it forms a contractile 'rubber band' that sequesters the basal end of the assembling daughter cytoskeleton [#4, #7]; it also directly binds the HAD phosphatase HAD2a to regulate basal complex contraction [#5]. Loss of MORN1 abolishes basal complex assembly, produces multi-headed conjoined 'Janus' parasites with defective apicoplast segregation, and severely attenuates growth and virulence [#2, #3]. TgMORN1 is a direct binding target of the small molecule Licochalcone A, with residues S168 and D203 implicated in modulating its thermal stability [#8].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Establishing where MORN1 acts addressed whether a candidate cytoskeletal protein participates in parasite division: it localizes to dynamic apical/posterior IMC rings and the centrocone and links membrane regions to the cytoskeleton.\",\n      \"evidence\": \"YFP fusion, time-lapse live imaging, overexpression phenotyping, and detergent fractionation in T. gondii\",\n      \"pmids\": [\"16684814\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular partners not yet identified\", \"Overexpression phenotype does not establish endogenous loss-of-function role\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Testing whether MORN1 function is conserved across parasites and life stages showed posterior-ring localization during T. gondii endopolygeny, Eimeria and P. falciparum schizogony, and during sexual microgamete budding, indicating a broadly conserved role in IMC assembly.\",\n      \"evidence\": \"Immunolocalization and staged expression analysis across T. gondii, Eimeria, and P. falciparum\",\n      \"pmids\": [\"18310354\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional perturbation in any species\", \"Antibody-based localization only, single lab\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}, {\"species\": \"Eimeria\", \"strain\": \"\"}, {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Genetic ablation determined whether MORN1 is required for division, establishing it as essential for basal complex assembly, apicoplast segregation, and cytokinesis, with loss producing multi-headed 'Janus' parasites and attenuated virulence.\",\n      \"evidence\": \"Conditional null and Cre-LoxP knockouts with basal complex marker immunofluorescence, domain-deletion analysis, in vitro growth, and mouse virulence assays in T. gondii (two independent labs)\",\n      \"pmids\": [\"20808817\", \"20140195\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of apicoplast segregation coupling not resolved\", \"How MORN1 recruits downstream basal complex components not defined\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Defining the composition of the MORN1 complex addressed what MORN1 scaffolds, cataloguing basal complex components including one recruited only in mature parasites and confirming MORN1 as the assembly scaffold.\",\n      \"evidence\": \"Subcellular fractionation, MORN1 affinity purification, and mass spectrometry in T. gondii\",\n      \"pmids\": [\"23027733\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct versus indirect interactions not distinguished\", \"Single lab, no reciprocal validation\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identifying HAD2a as a direct MORN1 partner linked the scaffold to a regulatory enzyme, implicating phosphatase activity in basal complex contraction and cytokinesis.\",\n      \"evidence\": \"Yeast two-hybrid with TgMORN1 bait, co-localization, conditional HAD2a knockout, and phosphatase activity assay in T. gondii\",\n      \"pmids\": [\"26840427\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological substrates of HAD2a at the basal complex unknown\", \"Mechanistic link from phosphatase activity to contraction not defined\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Structural analysis resolved the long-standing assumption about MORN repeats, showing they are protein-protein interaction modules that mediate antiparallel C-terminal dimerization and higher-order oligomers rather than lipid-binding domains.\",\n      \"evidence\": \"X-ray crystallography, SAXS, EM, and lipid-binding assays on MORN1 from T. gondii, T. brucei, and P. falciparum\",\n      \"pmids\": [\"33296386\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological relevance of extended versus V-shaped conformers in vivo not established\", \"How oligomer geometry maps to basal complex architecture unresolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}, {\"species\": \"Trypanosoma brucei\", \"strain\": \"\"}, {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Reciprocal proximity proteomics resolved the basal complex into distinct subcomplexes and identified the MORN1-BCC4 'rubber band' as the essential cell-division function of the structure.\",\n      \"evidence\": \"Reciprocal BioID, conditional expression disruption, and spatiotemporal immunofluorescence in T. gondii\",\n      \"pmids\": [\"35941170\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Contractile mechanism of the rubber band not biophysically defined\", \"Regulation of subcomplex assembly dynamics unresolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Chemical-genetic target identification established TgMORN1 as a direct binding target of Licochalcone A, offering a small-molecule handle on a cytoskeletal scaffold essential for parasite division.\",\n      \"evidence\": \"SPR-MS target ID, RNAi knockdown, NanoDSF, SPR, and Western blotting in T. gondii\",\n      \"pmids\": [\"41897346\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether S168/D203 binding disrupts MORN1 scaffolding function mechanistically unknown\", \"Single lab, effect on basal complex assembly not directly tested\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How MORN1 oligomer geometry and its HAD2a-linked phosphoregulation mechanically drive basal complex contraction to complete cytokinesis remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No biophysical model coupling MORN1 conformation to contractile force\", \"Substrates of HAD2a at the basal complex unidentified\", \"Recruitment hierarchy of basal complex subcomplexes not fully ordered\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 2, 4, 7], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0042803\", \"supporting_discovery_ids\": [6], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}, {\"species\": \"Trypanosoma brucei\", \"strain\": \"\"}, {\"species\": \"Plasmodium falciparum\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0005515\", \"supporting_discovery_ids\": [5, 6, 7], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0070938\", \"supporting_discovery_ids\": [0, 1, 2, 3, 4, 7], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0070258\", \"supporting_discovery_ids\": [0, 1], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [0], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0000910\", \"supporting_discovery_ids\": [2, 3, 7], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0051301\", \"supporting_discovery_ids\": [0, 2, 3], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [\n      \"Basal complex (MORN1 scaffold with multiple subcomplexes)\",\n      \"MORN1-BCC4 'rubber band' assembly\",\n      \"MORN1 antiparallel C-terminal homodimers/oligomers\"\n    ],\n    \"partners\": [\n      \"BCC4\",\n      \"HAD2a (HAD phosphatase)\",\n      \"Additional basal complex components identified by affinity purification/BioID\"\n    ],\n    \"other_free_text\": [\n      \"MORN repeats are protein-protein interaction modules, not lipid-binding domains [#6]\",\n      \"Linker between MORN domains 6 and 7 is critical for function; single MORN domain deletion abrogates function [#2]\",\n      \"Direct binding target of Licochalcone A at residues S168 and D203 [#8]\",\n      \"Conserved posterior-ring localization across asexual and sexual stages of T. gondii, Eimeria, and P. falciparum [#1]\"\n    ]\n  },\n  \"strain_conflicts\": []\n}\n```","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_310440","name":"MORN1","product":"membrane occupation and recognition nexus protein MORN1","uniprot_acc":"A0A125YJY8","chromosome":"TGME49_chrXI","start_pos":1342098},{"strain":"GT1","gene_id":"TGGT1_310440","name":null,"product":"membrane occupation and recognition nexus protein MORN1","uniprot_acc":null,"chromosome":"TGGT1_chrXI","start_pos":1306262},{"strain":"RH88","gene_id":"TGRH88_049970","name":null,"product":"membrane occupation and recognition nexus protein MORN1","uniprot_acc":null,"chromosome":"CM023092","start_pos":1392041},{"strain":"VEG","gene_id":"TGVEG_310440","name":null,"product":"membrane occupation and recognition nexus protein MORN1","uniprot_acc":"V5BHY7","chromosome":"TGVEG_chrXI","start_pos":1354889}]}