OVERLAPPING SUBSTRATE SPECIFICITIES OF BENZALDEHYDE DEHYDROGENASE (THE XYLC GENE-PRODUCT) AND 2-HYDROXYMUCONIC SEMIALDEHYDE DEHYDROGENASE (THE XYLG GENE-PRODUCT) ENCODED BY TOL PLASMID PWWO OF PSEUDOMONAS-PUTIDA
J. Inoue et al., OVERLAPPING SUBSTRATE SPECIFICITIES OF BENZALDEHYDE DEHYDROGENASE (THE XYLC GENE-PRODUCT) AND 2-HYDROXYMUCONIC SEMIALDEHYDE DEHYDROGENASE (THE XYLG GENE-PRODUCT) ENCODED BY TOL PLASMID PWWO OF PSEUDOMONAS-PUTIDA, Journal of bacteriology, 177(5), 1995, pp. 1196-1201
Two aldehyde dehydrogenases involved in the degradation of toluene and
xylenes, namely, benzaldehyde dehydrogenase and 2-hydroxymuconic semi
aldehyde dehydrogenase, are encoded by the xylC and xylG genes, respec
tively, on TOL plasmid pWW0 of Pseudomonas putida, The nucleotide sequ
ence of xylC was determined in this study, A protein exhibiting benzal
dehyde dehydrogenase activity had been purified from cells of P. putid
a(pWW0) (J. P. Shaw and S. Harayama, fur. J. Biochem, 191:705-714, 199
0); however, the aminoterminal sequence of this protein does not corre
spond to that predicted from the xylC sequence but does correspond to
that predicted from the xylG sequence. The protein purified in the ear
lier work was therefore 2-hydroxymuconic semialdehyde dehydrogenase (t
he xylG gene product). This conclusion was confirmed by the fact that
this protein oxidized 2-hydroxymuconic semialdehyde (k(cat)/K-m = 1.6
x 10(6) s(-1) M(-1)) more efficiently than benzaldehyde (k(cat)/K-m =
3.2 x 10(4) s(-1) M(-1)). The xylC product, the genuine benzaldehyde d
ehydrogenase, was purified from extracts of P. putida(pWW0-161 Delta x
ylG) which does not synthesize 2-hydroxymuconic semialdehyde dehydroge
nase. The amino-terminal sequence of the purified protein corresponds
to the aminoterminal sequence deduced from the xylC sequence, This enz
yme efficiently oxidized benzaldehyde (k(cat)/K-m = 1.7 x 10(7) s(-1)
M(-1)) and its analogs but did not oxidize 2-hydroxymuconic semialdehy
de or its analogs.