{"id":"95db92af-3beb-56f6-8824-92dbe700dd21","stable_key":"548ab9d6-3a9b-5bed-879c-17d03813b636:b2-met-etf-qo-iron-sulfur-entry","predicate":"accepts-electrons-via","statement":"Selective effects of ETF-QO FAD-site mutations supported electron entry from ETF through the [4Fe-4S] center, followed by flavin-mediated transfer to ubiquinone.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"5923f37e-3267-5a13-ab97-f633a0e2a413","mechanism_event_label":"ETF-QO uses its iron-sulfur center and flavin for different stages of the electron relay.","subject":{"id":"2f112303-db2d-5dce-9c4c-75103220fbc5","slug":"rhodobacter-etf-qo","display_name":"Rhodobacter sphaeroides ETF-QO","entity_type_key":"protein"},"object":{"id":"8058ae47-b091-5004-ba65-1e50ad91f70b","slug":"iron-sulfur-4fe4s","display_name":"[4Fe-4S] iron-sulfur cluster","entity_type_key":"chemical_species"},"evidence_count":1,"mechanism_event":{"id":"5923f37e-3267-5a13-ab97-f633a0e2a413","stable_key":"548ab9d6-3a9b-5bed-879c-17d03813b636:b2-met-etf-qo-iron-sulfur-entry-event","event_type":"biochemical_relationship","label":"ETF-QO uses its iron-sulfur center and flavin for different stages of the electron relay.","description":"Selective effects of ETF-QO FAD-site mutations supported electron entry from ETF through the [4Fe-4S] center, followed by flavin-mediated transfer to ubiquinone.","status":"provisional","compartment":{"slug":"mitochondria","display_name":"Mitochondria"},"participants":[{"entity":{"id":"8851f7f6-96e8-534d-ba5f-d3eab68eb3db","slug":"electron-transfer-flavoprotein","display_name":"Human electron transfer flavoprotein / ETF","entity_type_key":"protein_complex"},"role":"human electron donor","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"e2cd7179-f218-54e8-9ce9-7a836ae35fac","slug":"fad","display_name":"FAD","entity_type_key":"small_molecule"},"role":"downstream redox cofactor","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"ae9544c3-df78-54f8-80e7-5b643e5ba1cf","slug":"ubiquinone","display_name":"Ubiquinone","entity_type_key":"small_molecule"},"role":"terminal assay acceptor","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"89bcaf42-b4ab-5760-8c2e-44eace10cee0","slug":"iron","display_name":"Iron","entity_type_key":"nutrient_element"},"role":"cluster element","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""},{"entity":{"id":"2f112303-db2d-5dce-9c4c-75103220fbc5","slug":"rhodobacter-etf-qo","display_name":"Rhodobacter sphaeroides ETF-QO","entity_type_key":"protein"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":4,"notes":""},{"entity":{"id":"8058ae47-b091-5004-ba65-1e50ad91f70b","slug":"iron-sulfur-4fe4s","display_name":"[4Fe-4S] iron-sulfur cluster","entity_type_key":"chemical_species"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":5,"notes":""}]},"contexts":[{"dimension":"cross_nutrient","value_text":"Direct mechanistic integration of an iron-containing center with B2-derived FAD.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"evidence_spans","value_text":"[{\"source_bundle\": \"artifacts/riboflavin_metabolism_sources.json\", \"source_key\": \"PMC3106343\", \"locator\": \"HTML article p\", \"paragraph_index\": 51, \"char_start\": 0, \"char_end\": 1197, \"evidence_access\": \"full-text\"}]","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Recombinant Rhodobacter sphaeroides ETF-QO; 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topical membership is not evidence of a direct dietary effect.\nplain_language: ETF-QO uses its iron-sulfur center and flavin for different stages of the electron relay.\norganism: Rhodobacter sphaeroides; human ETF/MCAD reagents\ntissue_or_cell_type: Purified proteins\nexperimental_model: Recombinant Rhodobacter sphaeroides ETF-QO; human ETF and MCAD in mixed-species reconstitution; mutagenesis and EPR.\nlimitations: Mechanistic inference from mutagenesis/EPR and activity; no dietary iron or B2 intervention.\nexposure: No nutrient intervention; structural or biochemical characterization.\ncross_nutrient: Direct mechanistic integration of an iron-containing center with B2-derived FAD.\nevidence_spans: [{\"source_bundle\": \"artifacts/riboflavin_metabolism_sources.json\", \"source_key\": \"PMC3106343\", \"locator\": \"HTML article p\", \"paragraph_index\": 51, \"char_start\": 0, \"char_end\": 1197, \"evidence_access\": \"full-text\"}]\n[swanson-2008-etf-qo] The iron-sulfur cluster of electron transfer flavoprotein-ubiquinone oxidoreductase is the electron acceptor for electron transfer flavoprotein (2008). https://pubmed.ncbi.nlm.nih.gov/18672901/ DOI: 10.1021/bi800507p","model_system":"Recombinant Rhodobacter sphaeroides ETF-QO; 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