Cloning and sequences of the first eight genes of the chromosomally encoded (methyl) phenol degradation pathway from Pseudomonas putida P35X

Abstract

Pseudomonas putida P35X (NCIB 9869) metabolises phenol and cresols via a chromosomally encoded meta-cleavage pathway. A 13.4-kb fragment of the chromosome involved in encoding phenol catabolism was cloned and characterized. Deletion analysis and nucleotide sequencing of a 6589-bp region, in conjunction with enzyme assays, were used to identify the phhKLMNOP genes encoding the phenol hydroxylase, the phhB gene encoding catechol 2,3-dioxygenase (EC 1.13.11.2) and the phhQ gene that encodes a small ferredoxin-like protein. The genes are organised in an operon-like structure, in the order phhKLMNOPQB, and the deduced amino-acid sequences share high homology (68.3-99.7%) with those of the plasmid-encoded genes dmpKLMNOPQB of Pseudomonas sp. strain CF600. Genetic evidence is presented that the difference in the growth substrate ranges of Pseudomonas P35X and CF600 are due to the effector activation specificities of the regulators of these systems, rather than the substrate specificities of the catabolic enzymes.