Bacterial gallate catabolism by the GalA-D-B-C route

A reusable bacterial module for oxidative cleavage of gallate and conversion of the ring-opened product to pyruvate and oxaloacetate. An optional outer-membrane porin can facilitate substrate entry. GalA then cleaves the aromatic ring to the keto tautomer of 4-oxalomesaconate, GalD supplies the enol tautomer used by GalB, GalB hydrates that intermediate to 4-carboxy-4-hydroxy-2-oxoadipate, and GalC performs the terminal aldol cleavage. Regulation and downstream central metabolism are outside the module boundary.

GalP is optional because its porin activity and outer-membrane location are supported, but direct gallate specificity and pathway essentiality are not. The module begins chemically at extracellular or periplasm-accessible gallate and ends at pyruvate plus oxaloacetate. GalR regulation, the GalT inner-membrane transporter candidate, and metabolism of the terminal products are adjacent context rather than additional core reactions. Continuity of the GalA-D-B-C chain was manually verified against RHEA:28927, RHEA:28931, RHEA:17401, and RHEA:28935; the current derived chaining check is CoA-specific and does not evaluate these non-CoA intermediates.