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The cistronic organization of the bph locus, encoding a biphenyl/polychlorinated
biphenyl (PCB) degradation pathway in Pseudomonas sp. LB400, has been
elucidated. Seven structural genes, encoding biphenyl dioxygenase (bphA1A2A3A4),
biphenyl-2,3-dihydrodiol-2,3-dehydrogenase (bphB),
biphenyl-2,3-diol-1,2-dioxygenase (bphC) and
2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate hydrolase (bphD), have been located.
The complete sequences of bphB, bphC and bphD are reported. Taken together with
the data of Erickson and Mondello [J. Bacteriol. 174 (1992) 2903-2912],
Pseudomonas sp. LB400 is now the first strain for which the sequences of all
genes encoding the catabolism from biphenyls to benzoates have been determined.
Comparisons of the deduced amino acid (aa) sequences of BphB, BphC and BphD with
those of related proteins led to predictions about catalytically important aa
residues. Six Bph have been detected and identified. Five of them could be
obtained as the most abundant proteins when their genes were expressed in
Escherichia coli.
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