{"id":"1d669a11-642b-5d97-9fc4-f3914afa7509","stable_key":"46d15d9e-d3b5-544d-ba01-b785aa3e4f42:b1-pdh-phosphorylation-blocks-lipoyl-recognition","predicate":"reduces-binding-and-acetylation-of","statement":"Phosphorylated human site-1-only E1 lacked detectable lipoylated-L2 binding and reductive acetylation, despite high ThDP in the binding assay.","claim_class":"mechanistic","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"c2aab77f-6b77-5c1b-ab59-45d6f78a6fc4","mechanism_event_label":"Loading B1 cannot by itself undo this tested regulatory block: the phosphorylated enzyme fails to engage its lipoyl partner.","subject":{"id":"d4e93aea-ec8d-59fc-8010-da1c93683e52","slug":"pdh-e1-site1-phosphorylated","display_name":"PDH E1 phosphorylated at alpha Ser264","entity_type_key":"protein_state"},"object":{"id":"12e22bc4-4bc8-5a45-87bc-9274656e9dab","slug":"dlat","display_name":"Dihydrolipoyl acetyltransferase / DLAT","entity_type_key":"protein"},"evidence_count":1,"mechanism_event":{"id":"c2aab77f-6b77-5c1b-ab59-45d6f78a6fc4","stable_key":"46d15d9e-d3b5-544d-ba01-b785aa3e4f42:b1-pdh-phosphorylation-blocks-lipoyl-recognition-event","event_type":"biochemical_relationship","label":"Loading B1 cannot by itself undo this tested regulatory block: the phosphorylated enzyme fails to engage its lipoyl partner.","description":"Phosphorylated human site-1-only E1 lacked detectable lipoylated-L2 binding and reductive acetylation, despite high ThDP in the binding assay.","status":"provisional","compartment":{"slug":"mitochondrial-matrix","display_name":"Mitochondrial matrix"},"participants":[{"entity":{"id":"187db168-8028-5ce6-9f8b-4bc61ebad1a0","slug":"thiamine-diphosphate","display_name":"Thiamine diphosphate","entity_type_key":"small_molecule"},"role":"present during binding measurement","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"d2a2b619-f60a-5ace-9bcb-cdf2a6e194e6","slug":"pyruvate-dehydrogenase-e1","display_name":"Human pyruvate dehydrogenase E1","entity_type_key":"protein_complex"},"role":"unphosphorylated comparator","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"d4e93aea-ec8d-59fc-8010-da1c93683e52","slug":"pdh-e1-site1-phosphorylated","display_name":"PDH E1 phosphorylated at alpha Ser264","entity_type_key":"protein_state"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"12e22bc4-4bc8-5a45-87bc-9274656e9dab","slug":"dlat","display_name":"Dihydrolipoyl acetyltransferase / DLAT","entity_type_key":"protein"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"evidence","value_text":"[{\"paper_key\": \"kato-2008-pdh-phosphorylation\", \"source_bundle\": \"artifacts/thiamine_metabolism_sources.json\", \"passage_ids\": [\"p-51\"], \"locator\": \"absence of L2 binding\", \"preservation\": \"Exact text retained in the source bundle; full source document retained when openly retrievable.\"}]","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Engineered human site-1-only E1; phosphorylation, ITC and kinetics.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Normal regulatory phosphorylation studied in an engineered construct; not a dietary deficiency or clinical nonresponse experiment.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient","value_text":"Thiamine (vitamin B1)","comparator":null,"unit":null,"notes":"","entity":{"slug":"thiamine","display_name":"Thiamine (vitamin B1)","entity_type_key":"small_molecule"}},{"dimension":"nutrient_topic","value_text":"Thiamine research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"thiamine","display_name":"Thiamine (vitamin B1)","entity_type_key":"small_molecule"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Loading B1 cannot by itself undo this tested regulatory block: the phosphorylated enzyme fails to engage its lipoyl partner.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[kato-2008-pdh-phosphorylation] Structural basis for inactivation of the human pyruvate dehydrogenase complex by phosphorylation: role of disordered phosphorylation loops (2008). https://pubmed.ncbi.nlm.nih.gov/19081061/ DOI: 10.1016/j.str.2008.10.010","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Purified proteins","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"d891a155-ab9f-5426-9137-851a3ab0be57","evidence_kind":"source_excerpt","locator":"Lines 704-715","start_line":704,"end_line":715,"excerpt":"### b1-pdh-phosphorylation-blocks-lipoyl-recognition\nPhosphorylated human site-1-only E1 lacked detectable lipoylated-L2 binding and reductive acetylation, despite high ThDP in the binding assay.\nCondition category: normal\nnutrient_topic: Thiamine research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Loading B1 cannot by itself undo this tested regulatory block: the phosphorylated enzyme fails to engage its lipoyl partner.\norganism: Homo sapiens\ntissue_or_cell_type: Purified proteins\nexperimental_model: Engineered human site-1-only E1; phosphorylation, ITC and kinetics.\nlimitations: Normal regulatory phosphorylation studied in an engineered construct; not a dietary deficiency or clinical nonresponse experiment.\nevidence: [{\"paper_key\": \"kato-2008-pdh-phosphorylation\", \"source_bundle\": \"artifacts/thiamine_metabolism_sources.json\", \"passage_ids\": [\"p-51\"], \"locator\": \"absence of L2 binding\", \"preservation\": \"Exact text retained in the source bundle; full source document retained when openly retrievable.\"}]\nnutrient: Thiamine (vitamin B1)\n[kato-2008-pdh-phosphorylation] Structural basis for inactivation of the human pyruvate dehydrogenase complex by phosphorylation: role of disordered phosphorylation loops (2008). https://pubmed.ncbi.nlm.nih.gov/19081061/ DOI: 10.1016/j.str.2008.10.010","model_system":"Engineered human site-1-only E1; phosphorylation, ITC and kinetics.","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [kato-2008-pdh-phosphorylation] Structural basis for inactivation of the human pyruvate dehydrogenase complex by phosphorylation: role of disordered phosphorylation loops (2008). https://pubmed.ncbi.nlm.nih.gov/19081061/ DOI: 10.1016/j.str.2008.10.010","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"158d2c03-ac8c-589f-8270-c468165ae346","stable_key":"import-46d15d9e-d3b5-544d-ba01-b785aa3e4f42","title":"Thiamine: mechanisms, deficiency and nutrient interactions (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"f376512fb3310141315548015b387833e3af45146e73fb73cd02cee20e4ddb9c","revision_id":"53bc5eda-dec8-58cc-a56f-a9eb4ab036ef","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}