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Appl. Environ. Microbiol., 08 1996, 2710-2715, Vol 62, No. 8
M Sylvestre, Y Hurtubise, D Barriault, J Bergeron and D Ahmad
2,3-Dihydro-2,3-dihydroxybiphenyl-2,3-dehydrogenase (B2,3D) catalyzes the
second step in the biphenyl degradation pathway. The nucleotide sequence of
Comamonas testosteroni B-356 bphB, which encodes B2,3D, was determined.
Structural analysis showed that the dehydrogenases involved in the
bacterial degradation of aromatic compounds are related to each other and
that their phylogenetic relationships are very similar to the relationships
observed for dioxygenases that catalyze the initial reaction in the
degradation pathway. The bphB sequence was used to produce recombinant
active His-tagged B2,3D, which allowed us to describe for the first time
some of the main features of a B2,3D. This enzyme requires NAD+, its
optimal pH is 9.5, and its native M(r) was found to be 123,000, which makes
it a tetramer. These characteristics are very similar to those reported for
the related enzyme cis-toluene dihydrodiol dehydrogenase. The Km value and
maximum rate of metabolism for 2,3-dihydro-2,3-dihydroxybiphenyl were 73
+/- 16 microM and 46 +/- 4 nmol min-1 microgram-1, respectively. Compared
with the cis-toluene dihydrodiol dehydrogenase, B2,3D appeared to be more
substrate specific since it was unable to attack
cis-1,2-dihydroxy-cyclohexa-3,5-diene.
Copyright © 1996, American Society for Microbiology
Characterization of active recombinant 2,3-dihydro-2,3- dihydroxybiphenyl dehydrogenase from Comamonas testosteroni B-356 and sequence of the encoding gene (bphB)
Institut National de la Recherche Scientifique-Sante, Universite du Quebec, Canada. Michel_Sylvestre@INRS-Sante.UQuebec.ca
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