Identification of cellulose synthase(s) in higher plants: sequence analysis of processive β-glycosyltransferases with the common motif ’D, D, D35Q(R,Q)XRW‘

摘要: More than ten β-glycosyltransferases are now recognized that have limited similarity to the amino acid sequence of cellulose synthase from Acetobacter xylinum. Using hydrophobic cluster analysis (HCA), we recently identified two domains and putative catalytic residues in processive β-glycosyltransferases. In this study, found expressed tags (ESTs) higher plants (Arabidopsis thaliana, Brassica campestris, Oryza sativa) exhibit a A. xylinum synthase. These ESTs contain some conserved Complete sequencing an EST clone (T88271) thaliana led identification all derived truncated polypeptide which appears be part Sequence comparison proteins with known function several unidentified ‘D, D, D35Q(R,Q)XRW’ motif is considered strong predictor for β-glycosyltransferasesthat includes, among other proteins, chitin synthases. The first aspartic were analysed by site-directed mutagenesis, their replacement another loss activity xylinum, suggesting they essential enzyme activity. A correlation between second residue (R or Q) Q(R,Q)XRW synthesis along glucan chain (polysaccharide) short chain(oligosaccharide) suggests may involved degree processivity