title: A non-NadB type L-aspartate dehydrogenase from Ralstonia eutropha strain JMP134: molecular characterization and physiological functions.
abstract: We report the molecular characterization and physiological function of a novel L-aspartate dehydrogenase (AspDH). The purified enzyme was a 28-kDa dimeric protein, exhibiting high catalytic activity for L-aspartate (L-Asp) oxidation using NAD and/or NADP as cofactors. Quantitative real-time PCR analysis indicated that the genes involved in the AspDH gene cluster, poly-3-hydroxyalkanoate (PHA) biosynthesis, and the TCA cycle were substantially induced by L-Asp in wild-type cells. In contrast, expression of the aspartase and aspartate aminotransferase genes was substantially induced in the AspDH gene knockout mutant (ΔB3576) but not in the wild type. GC-MS analyses revealed that the wild-type strain synthesized poly-3-hydroxybutyrate from fructose or L-Asp, whereas the ΔB3576 mutant did not synthesize PHA from L-Asp. AspDH gene cluster products might be involved in the biosynthesis of the PHA precursor, revealing that AspDH was a non-NadB type enzyme, and thus entirely different from the previously reported NadB type enzymes working in NAD biosynthesis.
authors.affiliation: Department of Life Science and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Shimane, Japan.
authors.forename: Yinxia
authors.initials: Y
authors.lastname: Li
authors.forename: Manabu
authors.initials: M
authors.lastname: Ishida
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ashida
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Shibata
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sawa
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001219:Aspartate Aminotransferases / Q000235:genetics / Q000378:metabolism; D001224:Aspartic Acid / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D003001:Cloning, Molecular; D020118:Cupriavidus necator / Q000201:enzymology* / Q000235:genetics; D019281:Dimerization; D004926:Escherichia coli; D017353:Gene Deletion; D015870:Gene Expression; D006885:Hydroxybutyrates / Q000378:metabolism; D007700:Kinetics; D013058:Mass Spectrometry; D009243:NAD / Q000378:metabolism*; D009249:NADP / Q000378:metabolism*; D011091:Polyesters / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D014169:Transformation, Bacterial; D000094122:Polyhydroxybutyrates
chemical_list: D000594:Amino Acid Oxidoreductases; D001219:Aspartate Aminotransferases; D001224:Aspartic Acid; D001426:Bacterial Proteins; D006885:Hydroxybutyrates; D009243:NAD; D009249:NADP; D011091:Polyesters; D011994:Recombinant Proteins; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates; C025745:aspartate dehydrogenase