LOCATION AND SEQUENCE-ANALYSIS OF A 2-HYDROXY-6-OXO-6-PHENYLHEXA-2,4-DIENOATE HYDROLASE-ENCODING GENE (BPDF) OF THE BIPHENYL POLYCHLORINATED BIPHENYL DEGRADATION PATHWAY IN RHODOCOCCUS SP M5/

The 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate (HOPD) hydrolase-encodin g gene (bpdF) in the biphenyl (BP)/polychlorinated biphenyl (PCB)-degr ading bacterium, Rhodococcus sp. M5 (M5), was found to be located with in a 4.5-kb HindIII-BamHI genomic DNA that was 5.4 kb downstream from the bpdC1C2BADE gene cluster. The deduced amino acid (aa) sequence of bpdF revealed that the hydrolase contains 297 aa (32 679 Da) that was verified by expression in the Escherichia coli T7 RNA polymerase/promo ter system. Unlike previously known HOPD hydrolases, the aa sequence o f BpdF appears unique. Interestingly, all HOPD hydrolases and related proteins from the phenol and toluene/ xylene degradation pathways, wer e found to have a bias in the codon usage in the catalytic Ser within the conserved VGNS(M/F)GG motif.