{"id":"268926fa-436b-5c72-8ae8-e2b4031e2d96","stable_key":"31b1baa4-4113-5541-b9e7-fe44a5253a07:pabc-rescue","predicate":"increases_in_recorded_experiment","statement":"External pABA supports growth of the disrupted-pabC strain.","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"e3c3bc00-e6b5-5909-991e-20473dc6c4ea","mechanism_event_label":"External pABA supports growth of the disrupted-pabC strain.","subject":{"id":"eef4779e-36ce-504c-be2c-a72bdb64f22d","slug":"4-aminobenzoate","display_name":"4-Aminobenzoate / pABA","entity_type_key":"small_molecule"},"object":{"id":"f9706cc6-da2c-56a5-aade-074bdd40195d","slug":"ecoli-pabc-deficient-growth","display_name":"Growth of PabC-deficient E. coli","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"e3c3bc00-e6b5-5909-991e-20473dc6c4ea","stable_key":"31b1baa4-4113-5541-b9e7-fe44a5253a07:pabc-rescue-event","event_type":"experimental_observation","label":"External pABA supports growth of the disrupted-pabC strain.","description":"**The folate branch contains a B6-dependent step.** In E. coli, PabA supplies nitrogen from glutamine, generating glutamate; PabB uses chorismate and that nitrogen to form 4-amino-4-deoxychorismate. PabC then cleaves this intermediate to p-aminobenzoate (pABA) and pyruvate. The purified PabC enzyme contains pyridoxal phosphate (PLP), a B6 cofactor. A disrupted pabC strain required external pABA for growth. This establishes a microbial cofactor and biosynthetic dependency, not that marginal human B6 deficiency causes microbial folate failure. pABA is a precursor used in bacterial folate synthesis, not folate itself. [para-aminobenzoate synthesis from chorismate occurs in two steps.](https://pubmed.ncbi.nlm.nih.gov/2656685/) [Characterization and sequence of Escherichia coli pabC, the gene encoding aminodeoxychorismate lyase, a pyridoxal phosphate-containing enzyme.](https://pubmed.ncbi.nlm.nih.gov/1644759/)","status":"provisional","compartment":null,"participants":[{"entity":{"id":"eef4779e-36ce-504c-be2c-a72bdb64f22d","slug":"4-aminobenzoate","display_name":"4-Aminobenzoate / pABA","entity_type_key":"small_molecule"},"role":"tested factor","stoichiometry":null,"state_label":"External pABA in disrupted-pabC background","sequence_order":0,"notes":""},{"entity":{"id":"f9706cc6-da2c-56a5-aade-074bdd40195d","slug":"ecoli-pabc-deficient-growth","display_name":"Growth of PabC-deficient E. coli","entity_type_key":"cellular_process"},"role":"measured outcome","stoichiometry":null,"state_label":"increase","sequence_order":1,"notes":""},{"entity":{"id":"03b17dae-6284-55ba-a8c1-42f80d104a31","slug":"ecoli-pabc","display_name":"Escherichia coli aminodeoxychorismate lyase / PabC","entity_type_key":"protein"},"role":"impaired enzyme","stoichiometry":null,"state_label":"","sequence_order":2,"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 disrupted-pabC strain without external pABA","unit":null,"notes":"Condition belongs to the full experimental contrast; do not separate a joint intervention.","entity":{"slug":"4-aminobenzoate","display_name":"4-Aminobenzoate / pABA","entity_type_key":"small_molecule"}},{"dimension":"experimental_condition","value_text":"disrupted","comparator":"Same disrupted-pabC strain without external pABA","unit":null,"notes":"Condition belongs to the full experimental contrast; do not separate a joint intervention.","entity":{"slug":"ecoli-pabc","display_name":"Escherichia coli aminodeoxychorismate lyase / PabC","entity_type_key":"protein"}},{"dimension":"experimental_contrast","value_text":"{\"intervention\": \"External pABA in disrupted-pabC background\", \"comparator\": \"Same disrupted-pabC strain without external pABA\", \"endpoint\": \"External pABA supports growth of the disrupted-pabC strain.\", \"effect_direction\": \"increase\", \"combination\": \"joint\", \"conditions\": [{\"entity_slug\": \"ecoli-pabc\", \"state\": \"disrupted\"}, {\"entity_slug\": \"4-aminobenzoate\", \"state\": \"supplied\"}]}","comparator":null,"unit":null,"notes":"Explicit extracted experimental comparison; source-derived draft.","entity":null},{"dimension":"experimental_model","value_text":"E. coli genetic machinery impairment and nutritional rescue.","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. The complete source passage retains qualifications; unspecified doses/timing have not been extracted here. No clinical efficacy, nutrient deficiency or unique molecular mediation is inferred.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"External pABA supports growth of the disrupted-pabC strain.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"Characterization and sequence of Escherichia coli pabC, the gene encoding aminodeoxychorismate lyase, a pyridoxal phosphate-containing enzyme. | 1992 | DOI 10.1128/jb.174.16.5317-5323.1992 | PMID 1644759 | https://pubmed.ncbi.nlm.nih.gov/1644759/ | https://doi.org/10.1128/jb.174.16.5317-5323.1992 | https://pmc.ncbi.nlm.nih.gov/articles/PMC206368/","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"para-aminobenzoate synthesis from chorismate occurs in two steps. | 1989 | DOI 10.1016/s0021-9258(18)81833-6 | PMID 2656685 | https://pubmed.ncbi.nlm.nih.gov/2656685/ | https://doi.org/10.1016/s0021-9258(18)81833-6","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"source_locator","value_text":"Reviewed reference lines 25-25; exact primary location described in quoted passage where extracted.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"trigger_kind","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null}],"evidence":[{"id":"a8c96aea-9b57-5bd8-a84d-856999c5df83","evidence_kind":"source_excerpt","locator":"Lines 25-25","start_line":25,"end_line":25,"excerpt":"**The folate branch contains a B6-dependent step.** In E. coli, PabA supplies nitrogen from glutamine, generating glutamate; PabB uses chorismate and that nitrogen to form 4-amino-4-deoxychorismate. PabC then cleaves this intermediate to p-aminobenzoate (pABA) and pyruvate. The purified PabC enzyme contains pyridoxal phosphate (PLP), a B6 cofactor. A disrupted pabC strain required external pABA for growth. This establishes a microbial cofactor and biosynthetic dependency, not that marginal human B6 deficiency causes microbial folate failure. pABA is a precursor used in bacterial folate synthesis, not folate itself. [para-aminobenzoate synthesis from chorismate occurs in two steps.](https://pubmed.ncbi.nlm.nih.gov/2656685/) [Characterization and sequence of Escherichia coli pabC, the gene encoding aminodeoxychorismate lyase, a pyridoxal phosphate-containing enzyme.](https://pubmed.ncbi.nlm.nih.gov/1644759/)","model_system":"E. coli genetic machinery impairment and nutritional rescue.","directness":"reported_statement","verification_status":"source_derived_draft","notes":"Exact excerpt of the retained AI-assisted reviewed reference; primary sources are cited in primary_references and access scope is retained. Not a verbatim quotation from a primary paper.","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"e6ae59de-0369-5c2f-8262-57d91302671c","stable_key":"import-31b1baa4-4113-5541-b9e7-fe44a5253a07","title":"Shikimic acid: detailed mechanisms of action (reviewed 5 October 2026)","document_type":"imported_text","citation_label":"Original AI-assisted review of primary studies and, where relevant, official regulatory records. Access level is retained per claim. Corrections, null results and unresolved questions remain explicit. Not publisher full text or independent replication.","file_path":"","sha256":"95b1f9e9577661312d67f36e156d2e49326b207f296c1c0e801a5b007fd8e283","revision_id":"cd3237f1-131a-557d-84b5-7543259807b0","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}