title: Site Directed Mutagenesis of Dextransucrase DsrM from Weissella cibaria: Transformation to a Reuteransucrase.
abstract: Glucansucrases produce α-glucans and gluco-oligosaccharides; the linkage type and molecular weight of glucans impacts their functionality. This study compared the catalytic specificities of dextransucrase DsrM from Weissella cibaria 10M and derivatives of this enzymes with GtfA from Lactobacillus reuteri TMW1.656. The N-variable region, which is dispensable for GtfA activity, was essential for DsrM activity. Parallel amino acid substitutions in DsrM-ΔS and GtfA-ΔN indicated that the acceptor binding site residues determining the linkage type differ in these enzymes. DsrM-V583P:V586I had comparable enzyme activity as the respective GtfA derivative but did not increase the proportion of α-(1→4) linkages. DsrM-S622N had low enzyme activity and an unaltered proportion of α-(1→4) linkages while the analogous GtfA-S1062N maintained enzyme activity but increased the proportion of α-(1→4) linkages. This study of dextransucrase from Weissella spp. thus elucidated differences between glucansucrases and will facilitate study of the structure-function relationships of dextran and isomalto-oligosaccharides.
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta , Edmonton AB T6G 2R3, Canada.
authors.forename: Xiao Yan
authors.initials: XY
authors.lastname: Chen
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta , Edmonton AB T6G 2R3, Canada.|College of Bioengineering and Food Science, Hubei University of Technology , Wuhan 430068, P.R. China.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Gänzle
mesh_terms: D019943:Amino Acid Substitution; D001665:Binding Sites; D003911:Dextrans / Q000737:chemistry; D005936:Glucans / Q000737:chemistry; D005964:Glucosyltransferases / Q000737:chemistry / Q000235:genetics*; D052200:Limosilactobacillus reuteri / Q000201:enzymology; D016297:Mutagenesis, Site-Directed; D009844:Oligosaccharides; D013393:Sucrase / Q000737:chemistry / Q000235:genetics*; D058836:Weissella / Q000201:enzymology* / Q000235:genetics
chemical_list: D003911:Dextrans; D005936:Glucans; D009844:Oligosaccharides; D005964:Glucosyltransferases; C020025:dextransucrase; D013393:Sucrase
keywords: Weissella cibaria 10M; dextran; dextransucrase; reuteran; reuteransucrase; structure−function relationship