title: Mutations inducing an active-site aperture in Rhizobium sp. sucrose isomerase confer hydrolytic activity.
abstract: Sucrose isomerase is an enzyme that catalyzes the production of sucrose isomers of high biotechnological and pharmaceutical interest. Owing to the complexity of the chemical synthesis of these isomers, isomaltulose and trehalulose, enzymatic conversion remains the preferred method for obtaining these products. Depending on the microbial source, the ratio of the sucrose-isomer products varies significantly. In studies aimed at understanding and explaining the underlying molecular mechanisms of these reactions, mutations obtained using a random-mutagenesis approach displayed a major hydrolytic activity. Two of these variants, R284C and F164L, of sucrose isomerase from Rhizobium sp. were therefore crystallized and their crystal structures were determined. The three-dimensional structures of these mutants allowed the identification of the molecular determinants that favour hydrolytic activity compared with transferase activity. Substantial conformational changes resulting in an active-site opening were observed, as were changes in the pattern of water molecules bordering the active-site region.
authors: Laboratory for Biocrystallography and Structural Biology of Therapeutic Targets, Molecular and Structural Bases of Infectious Diseases, UMR 5086 CNRS and University of Lyon, 7 Passage du Vercors, F-69367 Lyon CEDEX 07, France.
authors: Alexandra
authors: A
authors: Lipski
authors: Hildegard
authors: H
authors: Watzlawick
authors: Stéphanie
authors: S
authors: Ravaud
authors: Xavier
authors: X
authors: Robert
authors: Moez
authors: M
authors: Rhimi
authors: Richard
authors: R
authors: Haser
authors: Ralf
authors: R
authors: Mattes
authors: Nushin
authors: N
authors: Aghajari
mesh_terms: D017485:1-Deoxynojirimycin / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D020134:Catalytic Domain / Q000235:genetics*; D018360:Crystallography, X-Ray / Q000379:methods; D004187:Disaccharides / Q000737:chemistry; D005947:Glucose / Q000737:chemistry; D005964:Glucosyltransferases / Q000737:chemistry* / Q000235:genetics*; D006868:Hydrolysis; D007534:Isomaltose / Q000031:analogs & derivatives / Q000737:chemistry; D008024:Ligands; D009154:Mutation; D011897:Random Allocation; D012231:Rhizobium / Q000201:enzymology* / Q000235:genetics; D013395:Sucrose / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D004187:Disaccharides; D008024:Ligands; D017485:1-Deoxynojirimycin; D013395:Sucrose; D007534:Isomaltose; D005964:Glucosyltransferases; C116853:sucrose isomerase; C042003:trehalulose; D005947:Glucose; C008189:isomaltulose
keywords: Rhizobium sp.; isomaltulose; sucrose isomerase; trehalulose