Cloning and Sequence Analysis of the hpaD Gene Responsible for Homoprotocatechuate 2,3-Dioxygenase from Pseudomonas sp. DJ-12

The degradative pathway of homoprotocatechuate (HPC) is the bacterial route whereby 3,4-dihydroxyphenylacetic acid is catabolized to pyruvate and succinate by a series of sequential reactions. The HPC is catalized by homoprotocatechuate 2,3-dioxygenase (HPC-2,3O) to form 5-carboxymethyl-2-hydroxymuco semialdehyde. In this study, the hpaD gene encoding HPC-2,3O was cloned from the chromosomal DNA of Pseudomonas sp. DJ-12 and its nucleotide sequence was analyzed. The open reding frame of hpaD gene was found to be composed of 864 nucleotide pairs and to encode a polypeptide with 287 amino acid residues. The deduced amino acid sequence of the HPC-2,3O from Pseudomonas sp. DJ-12 exhibited 60-64% homology with those of the corresponding enzymes from E. coli, Salmonella enterica, and Klebsiella pneumoniae.