Genetic structure and functional implication of the fcb gene cluster for hydrolytic dechlorination of 4-chlorobenzoate from Pseudomonas sp DJ-12

The fcb gene cluster responsible for the hydrolytic dechlorination of 4-chl orobenzoate (4CBA) was cloned from the chromosomal DNA of Pseudomonas sp. D J-12, and its nucleotide sequence analyzed. The gene cluster was organized in the order fcbB-fcbA-fcbT1-fcbT2-cbT3-fcbC, which is different from that reported in other bacteria. A promoter-like sequence (-35 and -10 region) i s located upstream of the fcbB gene and putative ribosome-binding sequences were found upstream of the respective orfs. A stem-loop transcription term inator structure is found downstream of fcbC. This suggests that the six or fs are transcribed into a polycistronic mRNA. The FcbA, FcbB, and FcbC enzy mes for dechlorination of 4CBA have a relationship in common with the enzym es involved in fatty acid metabolism on the basis of their deduced amino ac id sequences. The proteins encoded by fcbT1, fcbT2, and fcbT3 show similari ty to those encoded by dctP, dctQ, and dctM of Rhodobacter capsulatus respe ctively, which encode transporter proteins for C4-dicarboxylate. It is like ly, therefore, that these proteins of DJ-12 play a role in transport of 4CB A into the cell. (C) 2000 Elsevier Science B.V. All rights reserved.