IDENTIFICATION OF THE BPHA4 GENE ENCODING FERREDOXIN REDUCTASE INVOLVED IN BIPHENYL AND POLYCHLORINATED BIPHENYL DEGRADATION IN PSEUDOMONASSP STRAIN KKS102

The nucleotide sequence of the downstream region of the bph operon fro m Pseudomonas sp. strain KKS102 was determined. Two open reading frame s (ORF1 and ORF2) were found in this region, and the deduced amino aci d sequence of ORF2 showed homology with the sequences of four ferredox in reductases of dioxygenase systems. When this region was inserted ju st upstream of the bph operon, which does not contain a gene encoding ferredoxin reductase, biphenyl dioxygenase activity uas detected. The 24- and 44-kDa polypeptides predicted from the two open reading frames were identified by sodium dodecyl sulfate-polyacrylamide gel electrop horesis. Crude extract which contained the products of ORF2 and bhpA1A 2A3 showed cytochrome c reduction activity. These data clearly suggest that ORF2 encodes ferredoxin reductase. The deduced amino acid sequen ce of ORF1 does not show significant homology with the sequences of an y other proteins in the SWISS-PROT data bank, and the function of ORF1 is unknown.