Classification of catechol 1,2-dioxygenase family: Sequence analysis of a gene for the catechol 1,2-dioxygenase showing high specificity for methylcatechols from Gram(+) aniline-assimilating Rhodococcus erythropolis AN-13

Gram(+) aniline-assimilating Rhodococcus erythropolis AN-13 (AN-13) produces catechol 1,2-dioxygenase (C120) showing high enzymatic activities for 3- and 4-methylcatechols [Aoki et al. (1984) Agric. Biol. Chem. 48, 2087-2095]. A 3.0 kb Sau3AI fragment carrying a gene encoding C120 (catA) was cloned by selection of transformants showing C120 activity from a gene library of AN-13. Furthermore, we specified a 1.6 kb SalI fragment containing catA from the Sau3AI fragment by subcloning. Sequence analysis revealed that the 1.6 kb Sail fragment carried a 855 bp open reading frame (ORF) encoding the entire AN-13 catA, preceded by a potential ribosome binding site (RBS). From comparison of the deduced amino acid (aa) sequence of C120 from AN-13 with other C120 reported previously, it was found that the AN-13 enzyme shares 56.0% aa sequence identity with C120 from Arthrobacter sp. mA3 (mA3) [Eck and Belter (1991) Gene 123, 87-92] compared with less than 36.4% aa sequence identities with others. In conclusion, we classified all C120 including the AN-13 enzyme into three subfamilies on the basis of similarity of aa sequences, numbers of aa residues, and substrate specificity.