{"id":"c59b1b54-baae-5661-944c-172421256a90","stable_key":"31b1baa4-4113-5541-b9e7-fe44a5253a07:ubic-rescue","predicate":"increases_in_recorded_experiment","statement":"External 4-hydroxybenzoate restored the precursor supply supporting ubiquinone production in ubiC-defective E. coli.","claim_class":"observational","status":"source_recorded","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"ca6a69e4-9c30-58ce-9cf0-d2f88233f45c","mechanism_event_label":"External 4-hydroxybenzoate restored the precursor supply supporting ubiquinone production in ubiC-defective E. coli.","subject":{"id":"2bc07760-1248-5bd4-b642-ce1980e64650","slug":"4-hydroxybenzoate","display_name":"4-Hydroxybenzoate","entity_type_key":"small_molecule"},"object":{"id":"ae2aa932-4288-5fe2-bb28-9d1f48ae66cf","slug":"ecoli-ubiquinone-production","display_name":"E. coli ubiquinone biosynthesis","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"ca6a69e4-9c30-58ce-9cf0-d2f88233f45c","stable_key":"31b1baa4-4113-5541-b9e7-fe44a5253a07:ubic-rescue-event","event_type":"experimental_observation","label":"External 4-hydroxybenzoate restored the precursor supply supporting ubiquinone production in ubiC-defective E. coli.","description":"**The K and Q branches are organism-specific.** Isotope experiments in E. coli traced shikimate carbon into the benzene ring of menaquinone-8 (MK-8), and methionine-derived methyl carbon into that product. This does not establish increased human MK-7, vitamin-K function or an oral shikimate dose response. Separately, an E. coli ubiC mutant failed to convert chorismate to 4-hydroxybenzoate and produced little ubiquinone unless supplied with 4-hydroxybenzoate. UbiC therefore identifies a branch-specific supply bottleneck; bacterial ubiquinone production is not synonymous with human mitochondrial CoQ10 synthesis. [The role of shikimic acid in the biosynthesis of vitamin K2.](https://pubmed.ncbi.nlm.nih.gov/5337721/) [Biosynthesis of ubiquinone in Escherichia coli K-12: biochemical and genetic characterization of a mutant unable to convert chorismate into 4-hydroxybenzoate.](https://pubmed.ncbi.nlm.nih.gov/4595202/)","status":"provisional","compartment":null,"participants":[{"entity":{"id":"2bc07760-1248-5bd4-b642-ce1980e64650","slug":"4-hydroxybenzoate","display_name":"4-Hydroxybenzoate","entity_type_key":"small_molecule"},"role":"tested factor","stoichiometry":null,"state_label":"4-Hydroxybenzoate supplied to ubiC mutant","sequence_order":0,"notes":""},{"entity":{"id":"ae2aa932-4288-5fe2-bb28-9d1f48ae66cf","slug":"ecoli-ubiquinone-production","display_name":"E. coli ubiquinone biosynthesis","entity_type_key":"cellular_process"},"role":"measured outcome","stoichiometry":null,"state_label":"increase","sequence_order":1,"notes":""},{"entity":{"id":"793a2db6-b0c7-5230-b8ef-f15e95fab2c0","slug":"ecoli-ubic","display_name":"Escherichia coli chorismate pyruvate-lyase / UbiC","entity_type_key":"protein"},"role":"impaired enzyme","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"ae9544c3-df78-54f8-80e7-5b643e5ba1cf","slug":"ubiquinone","display_name":"Ubiquinone","entity_type_key":"small_molecule"},"role":"downstream product family","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"availability_state","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null},{"dimension":"evidence_access","value_text":"Primary indexed abstract reviewed; full results, tables and supplements not independently extracted.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_condition","value_text":"supplied","comparator":"Same mutant without supplied precursor","unit":null,"notes":"Condition belongs to the full experimental contrast; do not separate a joint intervention.","entity":{"slug":"4-hydroxybenzoate","display_name":"4-Hydroxybenzoate","entity_type_key":"small_molecule"}},{"dimension":"experimental_condition","value_text":"defective","comparator":"Same mutant without supplied precursor","unit":null,"notes":"Condition belongs to the full experimental contrast; do not separate a joint intervention.","entity":{"slug":"ecoli-ubic","display_name":"Escherichia coli chorismate pyruvate-lyase / UbiC","entity_type_key":"protein"}},{"dimension":"experimental_contrast","value_text":"{\"intervention\": \"4-Hydroxybenzoate supplied to ubiC mutant\", \"comparator\": \"Same mutant without supplied precursor\", \"endpoint\": \"External 4-hydroxybenzoate restored the precursor supply supporting ubiquinone production in ubiC-defective E. coli.\", \"effect_direction\": \"increase\", \"combination\": \"joint\", \"conditions\": [{\"entity_slug\": \"ecoli-ubic\", \"state\": \"defective\"}, {\"entity_slug\": \"4-hydroxybenzoate\", \"state\": \"supplied\"}]}","comparator":null,"unit":null,"notes":"Explicit extracted experimental comparison; source-derived draft.","entity":null},{"dimension":"experimental_model","value_text":"E. coli K12 precursor-rescue experiment.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"interpretation_status","value_text":"Source-derived extraction of a fact-checked reference; access is explicit, not independent raw-data verification.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Interpret only within the recorded preparation, exposure and comparator. 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This does not establish increased human MK-7, vitamin-K function or an oral shikimate dose response. Separately, an E. coli ubiC mutant failed to convert chorismate to 4-hydroxybenzoate and produced little ubiquinone unless supplied with 4-hydroxybenzoate. UbiC therefore identifies a branch-specific supply bottleneck; bacterial ubiquinone production is not synonymous with human mitochondrial CoQ10 synthesis. [The role of shikimic acid in the biosynthesis of vitamin K2.](https://pubmed.ncbi.nlm.nih.gov/5337721/) [Biosynthesis of ubiquinone in Escherichia coli K-12: biochemical and genetic characterization of a mutant unable to convert chorismate into 4-hydroxybenzoate.](https://pubmed.ncbi.nlm.nih.gov/4595202/)","model_system":"E. coli K12 precursor-rescue experiment.","directness":"reported_statement","verification_status":"source_recorded","notes":"Exact excerpt of the retained AI-assisted reviewed reference; primary sources are cited in primary_references and access scope is retained. 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