title: Four critical aspartic acid residues potentially involved in the catalytic mechanism of Escherichia coli K-12 WaaR.
abstract: Escherichia coli K-12 WaaR is a non-processive alpha-1,2 glucosyltransferase, involved in the synthesis of the R-core of lipopolysaccharide. WaaR possesses the four conserved structural regions I, II, III and IV, each presumably involved in the mechanistic function in catalysis. Regions I and III contain the pair of strictly conserved Asp residues. Asp-129, 131 (region I) and 215, 217 (region III) of WaaR were individually converted to Asn by the site-directed mutagenesis of the waaR gene. All mutated enzymes were inactive, supporting the model for an alpha-glycosyl transfer reaction where the pair of strictly conserved aspartic acid residues in regions I and III play a critical role in the catalytic function.
authors.affiliation: Department of Bacteriology, Nagoya University, School of Medicine, Aichi, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Shibayama
authors.forename: S
authors.initials: S
authors.lastname: Ohsuka
authors.forename: K
authors.initials: K
authors.lastname: Sato
authors.forename: K
authors.initials: K
authors.lastname: Yokoyama
authors.forename: T
authors.initials: T
authors.lastname: Horii
authors.forename: M
authors.initials: M
authors.lastname: Ohta
mesh_terms: D001224:Aspartic Acid / Q000235:genetics / Q000378:metabolism*; D002240:Carbohydrate Sequence; D020134:Catalytic Domain; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009844:Oligosaccharides / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D029968:Escherichia coli Proteins; D008070:Lipopolysaccharides; D009844:Oligosaccharides; D001224:Aspartic Acid; D005964:Glucosyltransferases; C000613736:WaaR protein, E coli