title: Molecular characterization of benzyl alcohol dehydrogenase and benzaldehyde dehydrogenase II of Acinetobacter calcoaceticus.
abstract: The nucleotide sequences of xylB and xylC from Acinetobacter calcoaceticus, the genes encoding benzyl alcohol dehydrogenase and benzaldehyde dehydrogenase II, were determined. The complete nucleotide sequence indicates that these two genes form part of an operon and this was supported by heterologous expression and physiological studies. Benzaldehyde dehydrogenase II is a 51654 Da protein with 484 amino acids per subunit and it is typical of other prokaryotic and eukaryotic aldehyde dehydrogenases. Benzyl alcohol dehydrogenase has a subunit Mr of 38923 consisting of 370 amino acids, it stereospecifically transfers the proR hydride of NADH, and it is a member of the family of zinc-dependent long-chain alcohol dehydrogenases. The enzyme appears to be more similar to animal and higher-plant alcohol dehydrogenases than it is to most other microbial alcohol dehydrogenases. Residue His-51 of zinc-dependent alcohol dehydrogenases is thought to be necessary as a general base for catalysis in this category of alcohol dehydrogenases. However, this residue was found to be replaced in benzyl alcohol dehydrogenase from A. calcoaceticus by an isoleucine, and the introduction of a histidine residue in this position did not alter the kinetic coefficients, pH optimum or substrate specificity of the enzyme. Other workers have shown that His-51 is also absent from the TOL-plasmid-encoded benzyl alcohol dehydrogenase of Pseudomonas putida and so these two closely related enzymes presumably have a catalytic mechanism that differs from that of the archetypal zinc-dependent alcohol dehydrogenases.
authors.affiliation: Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G128QQ, U.K.
authors.forename: D J
authors.initials: DJ
authors.lastname: Gillooly
authors.forename: A G
authors.initials: AG
authors.lastname: Robertson
authors.forename: C A
authors.initials: CA
authors.lastname: Fewson
mesh_terms: D016954:Acinetobacter calcoaceticus / Q000201:enzymology* / Q000235:genetics; D000429:Alcohol Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000445:Aldehyde Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005798:Genes, Bacterial; D015698:Genomic Library; D006736:Horses; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009876:Operon; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D010944:Plants / Q000201:enzymology; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D046911:Macromolecular Substances; D011994:Recombinant Proteins; D000429:Alcohol Oxidoreductases; C027016:benzyl alcohol dehydrogenase; D000445:Aldehyde Oxidoreductases; C027015:benzaldehyde dehydrogenase (NAD+); D017853:Phosphotransferases (Alcohol Group Acceptor); C032700:xylulokinase