Purification, characterization, and gene cloning of cis,cis-muconate cycloisomerase from benzamide-assimilating Arthrobacter sp. BA-5-17.

cis,cis-Muconate cycloisomerase (MC) was purified to homogeneity from benzamide-assimilating Arthrobacter sp. BA-5-17. The purified enzyme showed high activities for cis,cis-muconate and 3-methyl-cis,cis-muconate, and preferred the 3-substituted derivatives over the derivatives with the same substituent at the 2 position as a substrate. A gene encoding MC of strain BA-5-17 was cloned and named catB. The catB gene was clustered with catR encoding a putative LysR-type regulator, catC encoding a putative muconolactone isomerase, and catA-II encoding the catechol 1,2-dioxygenase isozymes CD-III-1 and III-2. These genes showed the same orientation in transcriptional direction and the organization of cloned genes was catRBCA-II. In the phylogenetic analysis of MCs and chloro-MCs, the BA-5-17 and Streptomyces setonii MCs formed a subfamily, clearly distinguished from those of other MCs.