Molecular cloning and expression of nahB gene from Pseudomonas fluorescens in E. coli

摘要

A gene encoding the cis-dihydrodiol naphthalene (DHN) dehydrogenase has been cloned from genomic DNA of Pseudomonas fluorescens SM11. The DNA fragment containing the nahB gene for the cis-DHN dehydrogenase was mapped with restriction endonucleases and sequenced. The DNA fragment contained an ORF of 780 bp encoding a polypeptide of 260 amino acid residues. The amino acid sequences of the enzyme revealed several conserved regions with those of the corresponding enzyme encoded in other strains of Pseudomonas. The homology of the amino acid sequence is 93 percent identity with that of the enzyme by P. putida OUS82. It is assumed that the cis-DHN dehydrogenase consists of four 28,800 molecular weight subunits and is specific for NAD as an electron acceptor for catalytic function.