Catechol ortho-cleavage branch of the beta-ketoadipate pathway

A reusable bacterial aromatic-catabolism module for the catechol ortho-cleavage branch that converts catechol to beta-ketoadipate enol-lactone. The branch begins with intradiol cleavage of catechol to cis,cis-muconate by a CatA-like catechol 1,2-dioxygenase, followed by CatB-like muconate cycloisomerase and CatC-like muconolactone delta-isomerase steps. In Pseudomonas putida KT2440, CatA-I/PP_3713 and CatA-II/PP_3166 provide paralogous catechol 1,2-dioxygenase exemplars, CatB/PP_3715 supplies the muconate cycloisomerase step, and CatC/PP_3714 supplies the isomerase step. The module starts at catechol, the output of upstream aromatic upper pathways such as BenABCD benzoate degradation, and stops before the shared lower beta-ketoadipate reactions that convert the enol-lactone toward central metabolism.

First-pass PSEPK interpretation: ppu00361 contributes CatA-I, CatA-II, and CatB, but its KEGG map label is broader than the native KT2440 module. The reusable module is the catechol ortho-cleavage branch: CatA converts catechol to cis,cis-muconate, CatB converts cis,cis-muconate to muconolactone, and CatC converts muconolactone to beta-ketoadipate enol-lactone. CatC is included despite being assigned to neighboring ppu00362/ppu01220 buckets because it is required for a complete catechol branch. Downstream enol-lactone hydrolase, CoA-transferase, and thiolase steps are shared beta-ketoadipate lower-pathway chemistry and should be modeled separately. OpenScientist module-level and PSEPK-specific retrieval both support this boundary and flag the ppu00361 chlorinated-aromatic label as an over-broad database-map framing for KT2440.