Molecular cloning of the nahG gene encoding salicylate hydroxylase from Pseudomonas fluorescens

A gene encoding the salicylate hydroxylase was cloned from the genomic DNA of Pseudomonas fluorescens SME11. The DNA fragment containing the nahG gene for the salicylate hydroxylase was mapped with restriction endonucleases and sequenced. The DNA fragment contained an ORF of 1,305 bp encoding a polypeptide of 434 amino acid residues. The nucleotide and amino acid sequences of the salicylate hydroxylase revealed several conserved regions with those of the enzyme encoded in P. putida PpG7: The homology of the nucleotide sequence is 83% and that of amino acid sequence is 72%. We found large conserved regions of the amino acid sequence at FAD and NADH binding regions. The FAD binding site is located at the amino terminal region and a lysine residue functions as a NADH-binding site.