Benzoate upper degradation pathway

A reusable bacterial aromatic-catabolism module for the upper benzoate degradation route that converts benzoate to catechol. The pathway begins with a multicomponent benzoate 1,2-dioxygenase system, represented here by BenA-like large oxygenase, BenB-like small oxygenase, and BenC-like reductase roles, and is followed by a BenD-like cis-diol dehydrogenase. Pseudomonas putida KT2440 benA/benB/benC/benD provide the local PSEPK exemplars for this module, but the module boundary is the conserved benzoate-to-catechol pathway segment rather than a PSEPK-specific locus definition.

First-pass PSEPK interpretation: benA/benB/benC/benD satisfy the upper benzoate degradation segment from benzoate to catechol. The broader KEGG ppu00622 "xylene degradation" bucket intersects several aromatic maps, but this module deliberately stops at catechol; catechol ring cleavage, 2-hydroxymuconate/4-oxalocrotonate steps, and the PP_1791/PP_2504 ppu00621 spillover genes belong in downstream catechol/meta-cleavage modules. The module also keeps the electron-transfer and oxygenase roles separate so that BenC is not represented as independently enabling the terminal oxygenase chemistry. CANDIDATE ASSESSED, NOT MODELLED — PcMNX1 (PMID:42567519): a 2026 report identifies PcMNX1, a group A flavoprotein monooxygenase from the white-rot fungus Phanerodontia (Phanerochaete) chrysosporium, as the enzyme performing NAD(P)H-dependent oxidative decarboxylation of the syringyl-unit intermediate syringate to dimethoxyhydroquinone, and also reports conversion of vanillate and 4-hydroxybenzoate — the cached abstract does not state the products for those two substrates. It is deliberately not added as a member here, for three reasons. (i) Chemistry: this module contains exactly two reactions — Rieske-type multicomponent dioxygenation of benzoate to cis-1,2-dihydroxycyclohexa-3,5-diene-1-carboxylate (GO:0018623), then NAD+-dependent cis-diol dehydrogenation to catechol (GO:0047116). PcMNX1 is a single-component group A FAD monooxygenase whose product is a hydroquinone, not the multicomponent Rieske dioxygenase plus SDR dehydrogenase pair modelled here, so it neither occupies an existing step nor supplies the cis-dihydrodiol BenD requires; accommodating it would redefine what this module is rather than extend its membership. (CO2 release is not itself a discriminator: BenD's own dehydrogenation step is decarboxylating and lists carbon dioxide among its products.) (ii) Substrate, route, and taxon: the physiological substrate is syringate, the products belong to the fungal lignin-aromatic hydroquinone route rather than the benzoate-to-catechol-to-beta-ketoadipate route this module feeds, benzoate itself is not among the reported substrates, and the module's declared context taxon is NCBITaxon:2 Bacteria. The reported vanillate activity is likewise a different fate for vanillate than the VanAB O-demethylation to protocatechuate modelled in hydroxycinnamate_vanillate_catabolism.yaml, so that module is not an alternative home either. (iii) Grounding: participants here are FAMILY selectors carrying an InterPro family id plus UniProtKB representative members, and no UniProtKB accession for PcMNX1 itself was retrievable — UniProt returns no entry cross-referencing PMID:42567519, and no entry for Phanerochaete chrysosporium under the gene name MNX1. The related GsMNX1 of Gelatoporia (Ceriporiopsis) subvermispora, which the same abstract names, was likewise not retrievable under that gene name, but it was not run down further; the gene symbol MNX1 is not unused in fungi (UniProtKB:G8B709, a Candida parapsilosis FAD-binding protein, carries it), so the searched-and-not-found claim here is deliberately narrow. The paper itself is cached abstract-only. Re-evaluate if a fungal lignin-derived aromatic catabolism module is created; that paper, with the GsMNX1 comparison and the bacterial 3-hydroxybenzoate 6-hydroxylase active-site analysis it reports, is good source material for one. This candidate is also recorded as a structured, queryable entry in this module's knowledge_gaps block (status OPEN), which carries the reference-level judgment and the re-evaluation trigger in machine-readable form.