Conserved structural regions involved in the catalytic mechanism of Escherichia coli K-12 WaaO (RfaI).
Escherichia coli K-12 WaaO (formerly known as RfaI) is a nonprocessive alpha-1,3 glucosyltransferase, involved in the synthesis of the R core of lipopolysaccharide. By comparing the amino acid sequence of WaaO with those of 11 homologous alpha-glycosyltransferases, four strictly conserved regions, I, II, III, and IV, were identified. Since functionally related transferases are predicted to have a similar architecture in the catalytic sites, it is assumed that these four regions are directly involved in the formation of alpha-glycosidic linkage from alpha-linked nucleotide diphospho-sugar donor. Hydrophobic cluster analysis revealed a conserved domain at the N termini of these alpha-glycosyltransferases. This domain was similar to that previously reported for beta-glycosyltransferases. Thus, this domain is likely to be involved in the formation of beta-glycosidic linkage between the donor sugar and the enzyme at the first step of the reaction. Site-directed mutagenesis analysis of E. coli K-12 WaaO revealed four critical amino acid residues.
Department of Bacteriology, School of Medicine, Nagoya University, Nagoya, 466-8550, Japan.
K
K
Shibayama
S
S
Ohsuka
T
T
Tanaka
Y
Y
Arakawa
M
M
Ohta
D000595:Amino Acid Sequence; D002240:Carbohydrate Sequence; D020134:Catalytic Domain; D016000:Cluster Analysis; D017124:Conserved Sequence; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid
C114999:K-12 lipopolysaccharide; D008070:Lipopolysaccharides; C036655:1,3-alpha-D-glucan synthase; D005964:Glucosyltransferases