Cloning and sequencing of the fcbB gene encoding 4-chlorobenzoate-coenzymeA dehalogenase from Pseudomonas sp. DJ-12

Pseudomonas sp, DJ-12 degrades 4-chlorobenzoate through hydrolytic dechlori nation to produce 4-hydroxybenzoate and a chloride ion. The fcbB gene encod ing the 4-chlorobenzoate-coenzyme A (4CBA-CoA) dehalogenase which catalyzes the nucleophilic substitution reaction to convert 4CBA-CoA to 4-hydroxyben zoate-coenzyme A (4HBA-CoA) in the consecutive steps of dechlorination was cloned from the chromosome of the organism. A nucleotide sequence analysis of the gene showed an open reading frame consisting of 810 nucleotides, whi ch can encode for a polypeptide of molecular mass 30 kDa, containing 269 am ino acid residues. A promoter-like sequence (-35 and -10 region) and a puta tive ribosome-binding sequence were identified. A deduced amino acid sequen ce of the 4CBA-CoA dehalogenase showed 86%, 50%, and 50% identity with thos e of corresponding enzymes in the Pseudomonas sp, CBS3, Arthrobacter sp, SU , and Arthrobacter sp. TM1, respectively.