Characterization of short-chain dehydrogenase/reductase homologues of Escherichia coli (YdfG) and Saccharomyces cerevisiae (YMR226C).
Short-chain dehydrogenase/reductase homologues from Escherichia coli (YdfG) and Saccharomyces cerevisiae (YMR226C) show high sequence similarity to serine dehydrogenase from Agrobacterium tumefaciens. We cloned each gene encoding YdfG and YMR226C into E. coli JM109 and purified them to homogeneity from the E. coli clones. YdfG and YMR226C consist of four identical subunits with a molecular mass of 27 and 29 kDa, respectively. Both enzymes require NADP(+) as a coenzyme and use L-serine as a substrate. Both enzymes show maximum activity at about pH 8.5 for the oxidation of L-serine. They also catalyze the oxidation of D-serine, L-allo-threonine, D-threonine, 3-hydroxyisobutyrate, and 3-hydroxybutyrate. The k(cat)/K(m) values of YdfG for L-serine, D-serine, L-allo-threonine, D-threonine, L-3-hydroxyisobutyrate, and D-3-hydroxyisobutyrate are 105, 29, 199, 109, 67, and 62 M(-1) s(-1), and those of YMR226C are 116, 110, 14600, 7540, 558, and 151 M(-1) s(-1), respectively. Thus, YdfG and YMR226C are NADP(+)-dependent dehydrogenases acting on 3-hydroxy acids with a three- or four-carbon chain, and L-allo-threonine is the best substrate for both enzymes.
Fujisawa
Hisae
H
Department of Bioresources Science, Kochi University, Nankoku, 783-8502, Kochi, Japan.
Nagata
Shinji
S
Misono
Haruo
H
D000429:Alcohol Oxidoreductases / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics; D005798:Genes, Bacterial; D005800:Genes, Fungal; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics; D016415:Sequence Alignment; D017385:Sequence Homology; D013379:Substrate Specificity
D029968:Escherichia coli Proteins; D029701:Saccharomyces cerevisiae Proteins; D000429:Alcohol Oxidoreductases; C104535:NADP+-dependent serine dehydrogenase