{"gene":"TG_258790","gene_symbol":"ECR1","run_date":"2026-09-08T12:58:25","timeline":{"discoveries":[{"year":2017,"finding":"ECR1 (essential for chromosome replication 1) is a 52-kDa protein containing divergent RING and TRAF-Sina-like zinc binding domains that localizes dynamically during the tachyzoite cell cycle: it first appears in the centrocone (spindle compartment of the nuclear envelope) in early S phase, then moves to the nucleus in late S phase at maximum expression, and is downregulated after nuclear division before daughter parasite separation.","method":"Forward genetic complementation of a temperature-sensitive mutant, live/fixed imaging of cell cycle-staged parasites, domain analysis","journal":"mBio","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — complementation of ts mutant with defined phenotypic readout, dynamic localization imaging; single lab, multiple methods but abstracts compress details","pmids":["28830940"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2017,"finding":"ECR1 is required for controlled chromosome replication; loss of ECR1 function causes lethal, uncontrolled chromosome replication phenotype similar to a topoisomerase-defective mutant at restrictive temperature (40°C).","method":"Temperature-sensitive mutant complementation screen and phenotypic analysis at restrictive temperature","journal":"mBio","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic complementation with clear phenotypic readout; single lab","pmids":["28830940"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2017,"finding":"ECR1 interacts with the ubiquitin-mediated protein degradation machinery and the minichromosome maintenance (MCM) complex as identified by proteomics; loss of ECR1 leads to increased stability of MCM2, indicating ECR1 promotes MCM2 degradation.","method":"Proteomics/co-immunoprecipitation mass spectrometry; protein stability assay upon ECR1 loss","journal":"mBio","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — proteomics interaction data combined with functional stability readout; single lab","pmids":["28830940"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2017,"finding":"ECR1 forms a stable complex with the cyclin-dependent kinase (CDK)-related kinase TgCrk5, and both proteins share similar cell cycle expression patterns and co-localize in the centrocone during tachyzoite replication.","method":"Proteomics/co-immunoprecipitation and co-localization imaging","journal":"mBio","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP interaction with supporting co-localization; single lab, two orthogonal approaches","pmids":["28830940"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"current_model":"ECR1 is a putative E3 ligase (bearing divergent RING and TRAF-Sina-like zinc-binding domains) that localizes to the Toxoplasma centrocone in early S phase and the nucleus in late S phase, where it forms a stable complex with the CDK-related kinase TgCrk5, interacts with the ubiquitin-proteasome machinery and the MCM complex, promotes MCM2 degradation, and is essential for controlled chromosome replication and proper mitotic progression during asexual tachyzoite division."},"narrative":{"mechanistic_narrative":"ECR1 (essential for chromosome replication 1) is a 52-kDa putative E3 ubiquitin ligase, bearing divergent RING and TRAF-Sina-like zinc-binding domains, that couples the ubiquitin-proteasome system to controlled chromosome replication during Toxoplasma gondii tachyzoite division [PMID:28830940]. It is dynamically staged in the cell cycle, appearing first in the centrocone (the spindle compartment of the nuclear envelope) in early S phase, then relocating to the nucleus at peak expression in late S phase before being downregulated after nuclear division [PMID:28830940]. ECR1 associates with the ubiquitin-mediated degradation machinery and the minichromosome maintenance (MCM) complex, and its loss stabilizes MCM2, indicating that ECR1 promotes MCM2 turnover to restrain DNA replication [PMID:28830940]. It also forms a stable complex with the CDK-related kinase TgCrk5, with which it shares expression timing and centrocone co-localization, linking ECR1 to cell-cycle kinase signaling [PMID:28830940]. Loss of ECR1 function causes lethal, uncontrolled chromosome replication resembling a topoisomerase-defective phenotype, establishing its essential role in gating replication and mitotic progression [PMID:28830940].","teleology":[{"year":2017,"claim":"Identifying ECR1 as the gene complementing a temperature-sensitive replication mutant established a previously uncharacterized RING/TRAF-Sina-domain protein as an essential, cell-cycle-staged regulator of tachyzoite division.","evidence":"Forward genetic complementation of a ts mutant with domain analysis and cell-cycle-staged live/fixed imaging in T. gondii","pmids":["28830940"],"confidence":"Medium","gaps":["E3 ligase catalytic activity not demonstrated biochemically","The signal driving centrocone-to-nucleus relocalization is unknown"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2017,"claim":"Phenotyping ECR1 loss at restrictive temperature showed it is required to gate chromosome replication, since its absence produces lethal uncontrolled replication like a topoisomerase-defective mutant.","evidence":"Temperature-sensitive mutant complementation and phenotypic analysis at 40°C in T. gondii","pmids":["28830940"],"confidence":"Medium","gaps":["Whether the replication defect is a direct consequence of lost ligase activity is untested","Downstream effects on mitotic progression not resolved mechanistically"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2017,"claim":"Proteomic mapping placed ECR1 in physical contact with the ubiquitin-degradation machinery and the MCM complex, and stabilization of MCM2 upon ECR1 loss provided a candidate substrate linking ECR1 to replication control.","evidence":"Co-IP mass spectrometry and MCM2 protein stability assay upon ECR1 loss in T. gondii","pmids":["28830940"],"confidence":"Medium","gaps":["Direct ubiquitination of MCM2 by ECR1 not demonstrated in vitro","Whether MCM2 degradation is the sole or primary effector of the replication phenotype is unresolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2017,"claim":"Co-IP and co-localization identified a stable ECR1–TgCrk5 complex, connecting the putative ligase to a CDK-related kinase acting at the centrocone.","evidence":"Co-immunoprecipitation and co-localization imaging in T. gondii","pmids":["28830940"],"confidence":"Medium","gaps":["Whether TgCrk5 phosphorylates ECR1 or regulates its activity is unknown","The functional consequence of the complex for replication control is uncharacterized"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":null,"claim":"Whether ECR1 possesses demonstrable E3 ligase activity and directly ubiquitinates MCM2, and how the ECR1–TgCrk5 complex is coordinated to gate replication, remain open.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No in vitro reconstitution of ECR1 ubiquitin ligase activity","No structural model of the RING/TRAF-Sina domains","Mechanism linking TgCrk5 kinase to ECR1-mediated MCM2 turnover unknown"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["ECR1–TgCrk5 complex","ECR1 association with the MCM (minichromosome maintenance) complex","ECR1 association with the ubiquitin-mediated degradation machinery"],"partners":["TGCRK5 (CDK-RELATED KINASE)","MCM2","MCM COMPLEX","UBIQUITIN-PROTEASOME DEGRADATION MACHINERY"],"other_free_text":["52-kDa protein with divergent RING and TRAF-Sina-like zinc-binding domains [#0]","Cell-cycle-staged: centrocone in early S phase, nucleus at peak in late S phase, downregulated after nuclear division [#0]","Loss of function causes lethal uncontrolled chromosome replication resembling a topoisomerase-defective mutant [#1]","Promotes MCM2 degradation; MCM2 is stabilized upon ECR1 loss [#2]"]},"strain_conflicts":[]},"prefetch_data":{},"corpus_meta":[{"pmid":"28830940","id":"PMC_28830940","title":"The Toxoplasma Centrocone Houses Cell Cycle Regulatory Factors.","date":"2017","source":"mBio","url":"https://pubmed.ncbi.nlm.nih.gov/28830940","citation_count":26,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":3155,"output_tokens":1044,"usd":0.012563,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":5982,"output_tokens":2676,"usd":0.048405,"stage2_stop_reason":"end_turn"},"total_usd":0.060968,"stage1_batch_id":"msgbatch_01TEPNZ4MCzJ7xtsNwosiDRk","stage2_batch_id":"msgbatch_01FQShM7n1sfCr4pWTDShmki","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2017,\n      \"finding\": \"ECR1 (essential for chromosome replication 1) is a 52-kDa protein containing divergent RING and TRAF-Sina-like zinc binding domains that localizes dynamically during the tachyzoite cell cycle: it first appears in the centrocone (spindle compartment of the nuclear envelope) in early S phase, then moves to the nucleus in late S phase at maximum expression, and is downregulated after nuclear division before daughter parasite separation.\",\n      \"method\": \"Forward genetic complementation of a temperature-sensitive mutant, live/fixed imaging of cell cycle-staged parasites, domain analysis\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — complementation of ts mutant with defined phenotypic readout, dynamic localization imaging; single lab, multiple methods but abstracts compress details\",\n      \"pmids\": [\"28830940\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ECR1 is required for controlled chromosome replication; loss of ECR1 function causes lethal, uncontrolled chromosome replication phenotype similar to a topoisomerase-defective mutant at restrictive temperature (40°C).\",\n      \"method\": \"Temperature-sensitive mutant complementation screen and phenotypic analysis at restrictive temperature\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic complementation with clear phenotypic readout; single lab\",\n      \"pmids\": [\"28830940\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ECR1 interacts with the ubiquitin-mediated protein degradation machinery and the minichromosome maintenance (MCM) complex as identified by proteomics; loss of ECR1 leads to increased stability of MCM2, indicating ECR1 promotes MCM2 degradation.\",\n      \"method\": \"Proteomics/co-immunoprecipitation mass spectrometry; protein stability assay upon ECR1 loss\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — proteomics interaction data combined with functional stability readout; single lab\",\n      \"pmids\": [\"28830940\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ECR1 forms a stable complex with the cyclin-dependent kinase (CDK)-related kinase TgCrk5, and both proteins share similar cell cycle expression patterns and co-localize in the centrocone during tachyzoite replication.\",\n      \"method\": \"Proteomics/co-immunoprecipitation and co-localization imaging\",\n      \"journal\": \"mBio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP interaction with supporting co-localization; single lab, two orthogonal approaches\",\n      \"pmids\": [\"28830940\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"current_model\": \"ECR1 is a putative E3 ligase (bearing divergent RING and TRAF-Sina-like zinc-binding domains) that localizes to the Toxoplasma centrocone in early S phase and the nucleus in late S phase, where it forms a stable complex with the CDK-related kinase TgCrk5, interacts with the ubiquitin-proteasome machinery and the MCM complex, promotes MCM2 degradation, and is essential for controlled chromosome replication and proper mitotic progression during asexual tachyzoite division.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ECR1 (essential for chromosome replication 1) is a 52-kDa putative E3 ubiquitin ligase, bearing divergent RING and TRAF-Sina-like zinc-binding domains, that couples the ubiquitin-proteasome system to controlled chromosome replication during Toxoplasma gondii tachyzoite division [#0]. It is dynamically staged in the cell cycle, appearing first in the centrocone (the spindle compartment of the nuclear envelope) in early S phase, then relocating to the nucleus at peak expression in late S phase before being downregulated after nuclear division [#0]. ECR1 associates with the ubiquitin-mediated degradation machinery and the minichromosome maintenance (MCM) complex, and its loss stabilizes MCM2, indicating that ECR1 promotes MCM2 turnover to restrain DNA replication [#2]. It also forms a stable complex with the CDK-related kinase TgCrk5, with which it shares expression timing and centrocone co-localization, linking ECR1 to cell-cycle kinase signaling [#3]. Loss of ECR1 function causes lethal, uncontrolled chromosome replication resembling a topoisomerase-defective phenotype, establishing its essential role in gating replication and mitotic progression [#1].\",\n  \"teleology\": [\n    {\n      \"year\": 2017,\n      \"claim\": \"Identifying ECR1 as the gene complementing a temperature-sensitive replication mutant established a previously uncharacterized RING/TRAF-Sina-domain protein as an essential, cell-cycle-staged regulator of tachyzoite division.\",\n      \"evidence\": \"Forward genetic complementation of a ts mutant with domain analysis and cell-cycle-staged live/fixed imaging in T. gondii\",\n      \"pmids\": [\"28830940\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"E3 ligase catalytic activity not demonstrated biochemically\",\n        \"The signal driving centrocone-to-nucleus relocalization is unknown\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Phenotyping ECR1 loss at restrictive temperature showed it is required to gate chromosome replication, since its absence produces lethal uncontrolled replication like a topoisomerase-defective mutant.\",\n      \"evidence\": \"Temperature-sensitive mutant complementation and phenotypic analysis at 40°C in T. gondii\",\n      \"pmids\": [\"28830940\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether the replication defect is a direct consequence of lost ligase activity is untested\",\n        \"Downstream effects on mitotic progression not resolved mechanistically\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Proteomic mapping placed ECR1 in physical contact with the ubiquitin-degradation machinery and the MCM complex, and stabilization of MCM2 upon ECR1 loss provided a candidate substrate linking ECR1 to replication control.\",\n      \"evidence\": \"Co-IP mass spectrometry and MCM2 protein stability assay upon ECR1 loss in T. gondii\",\n      \"pmids\": [\"28830940\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct ubiquitination of MCM2 by ECR1 not demonstrated in vitro\",\n        \"Whether MCM2 degradation is the sole or primary effector of the replication phenotype is unresolved\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Co-IP and co-localization identified a stable ECR1–TgCrk5 complex, connecting the putative ligase to a CDK-related kinase acting at the centrocone.\",\n      \"evidence\": \"Co-immunoprecipitation and co-localization imaging in T. gondii\",\n      \"pmids\": [\"28830940\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether TgCrk5 phosphorylates ECR1 or regulates its activity is unknown\",\n        \"The functional consequence of the complex for replication control is uncharacterized\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether ECR1 possesses demonstrable E3 ligase activity and directly ubiquitinates MCM2, and how the ECR1–TgCrk5 complex is coordinated to gate replication, remain open.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No in vitro reconstitution of ECR1 ubiquitin ligase activity\",\n        \"No structural model of the RING/TRAF-Sina domains\",\n        \"Mechanism linking TgCrk5 kinase to ECR1-mediated MCM2 turnover unknown\"\n      ],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0004842\", \"supporting_discovery_ids\": [0, 2], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0008270\", \"supporting_discovery_ids\": [0], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [0, 3], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0006511\", \"supporting_discovery_ids\": [2], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0006260\", \"supporting_discovery_ids\": [1, 2], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0007049\", \"supporting_discovery_ids\": [0, 3], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [\n      \"ECR1–TgCrk5 complex\",\n      \"ECR1 association with the MCM (minichromosome maintenance) complex\",\n      \"ECR1 association with the ubiquitin-mediated degradation machinery\"\n    ],\n    \"partners\": [\n      \"TgCrk5 (CDK-related kinase)\",\n      \"MCM2\",\n      \"MCM complex\",\n      \"ubiquitin-proteasome degradation machinery\"\n    ],\n    \"other_free_text\": [\n      \"52-kDa protein with divergent RING and TRAF-Sina-like zinc-binding domains [#0]\",\n      \"Cell-cycle-staged: centrocone in early S phase, nucleus at peak in late S phase, downregulated after nuclear division [#0]\",\n      \"Loss of function causes lethal uncontrolled chromosome replication resembling a topoisomerase-defective mutant [#1]\",\n      \"Promotes MCM2 degradation; MCM2 is stabilized upon ECR1 loss [#2]\"\n    ]\n  },\n  \"strain_conflicts\": []\n}","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_258790","name":"ECR1","product":"protein essential for chromosome replication ECR1","uniprot_acc":"A0A125YM02","chromosome":"TGME49_chrVIIb","start_pos":3179912},{"strain":"GT1","gene_id":"TGGT1_258790","name":null,"product":"zinc finger, C3HC4 type (RING finger) domain-containing protein","uniprot_acc":null,"chromosome":"TGGT1_chrVIIb","start_pos":3146410},{"strain":"RH88","gene_id":"TGRH88_071250","name":null,"product":"zinc finger, C3HC4 type (RING finger) domain-containing protein","uniprot_acc":null,"chromosome":"CM023089","start_pos":3206317},{"strain":"VEG","gene_id":"TGVEG_258790","name":null,"product":"zinc finger, C3HC4 type (RING finger) domain-containing protein","uniprot_acc":"B6KBA9","chromosome":"TGVEG_chrVIIb","start_pos":3198647}]}