Structural determinants of product specificity of sucrose isomerases

FEBS Lett. 2009 Jun 18;583(12):1964-8. doi: 10.1016/j.febslet.2009.05.002. Epub 2009 May 8.

Abstract

The healthy sweetener isomaltulose is industrially produced from the conversion of sucrose by the sucrose isomerase SmuA from Protaminobacter rubrum. Crystal structures of SmuA in native and deoxynojirimycin complexed forms completed with modeling studies unravel the characteristics of the isomaltulose synthases catalytic pocket and their substrate binding mode. Comparison with the trehalulose synthase MutB highlights the role of Arg(298) and Arg(306) active site residues and surface charges in controlling product specificity of sucrose isomerases (isomaltulose versus trehalulose). The results provide a rationale for the specific design of optimized enzymes.

MeSH terms

  • 1-Deoxynojirimycin / chemistry
  • Amino Acid Motifs
  • Amino Acid Sequence
  • Arginine / chemistry
  • Catalytic Domain / genetics
  • Crystallography, X-Ray
  • Gammaproteobacteria / enzymology
  • Gammaproteobacteria / genetics
  • Glucosamine / analogs & derivatives
  • Glucosamine / chemistry
  • Glucosyltransferases / chemistry
  • Glucosyltransferases / genetics
  • Glucosyltransferases / metabolism*
  • Intramolecular Transferases / chemistry
  • Intramolecular Transferases / genetics
  • Intramolecular Transferases / metabolism
  • Isomaltose / analogs & derivatives*
  • Isomaltose / biosynthesis
  • Isomaltose / isolation & purification
  • Macromolecular Substances
  • Models, Molecular
  • Protein Conformation
  • Static Electricity
  • Substrate Specificity
  • Sweetening Agents / isolation & purification
  • Sweetening Agents / metabolism

Substances

  • Macromolecular Substances
  • Sweetening Agents
  • deoxynojirimycine
  • 1-Deoxynojirimycin
  • Isomaltose
  • Arginine
  • Glucosyltransferases
  • sucrose isomerase
  • Intramolecular Transferases
  • isomaltulose synthase
  • Glucosamine
  • isomaltulose