Structure-Function Relationships of Glucansucrase and Fructansucrase Enzymes from Lactic Acid Bacteria
Open Access
- 1 March 2006
- journal article
- review article
- Published by American Society for Microbiology in Microbiology and Molecular Biology Reviews
- Vol. 70 (1), 157-176
- https://doi.org/10.1128/mmbr.70.1.157-176.2006
Abstract
SUMMARY: Lactic acid bacteria (LAB) employ sucrase-type enzymes to convert sucrose into homopolysaccharides consisting of either glucosyl units (glucans) or fructosyl units (fructans). The enzymes involved are labeled glucansucrases (GS) and fructansucrases (FS), respectively. The available molecular, biochemical, and structural information on sucrase genes and enzymes from various LAB and their fructan and α-glucan products is reviewed. The GS and FS enzymes are both glycoside hydrolase enzymes that act on the same substrate (sucrose) and catalyze (retaining) transglycosylation reactions that result in polysaccharide formation, but they possess completely different protein structures. GS enzymes (family GH70) are large multidomain proteins that occur exclusively in LAB. Their catalytic domain displays clear secondary-structure similarity with α-amylase enzymes (family GH13), with a predicted permuted (β/α) 8 barrel structure for which detailed structural and mechanistic information is available. Emphasis now is on identification of residues and regions important for GS enzyme activity and product specificity (synthesis of α-glucans differing in glycosidic linkage type, degree and type of branching, glucan molecular mass, and solubility). FS enzymes (family GH68) occur in both gram-negative and gram-positive bacteria and synthesize β-fructan polymers with either β-(2→6) (inulin) or β-(2→1) (levan) glycosidic bonds. Recently, the first high-resolution three-dimensional structures have become available for FS (levansucrase) proteins, revealing a rare five-bladed β-propeller structure with a deep, negatively charged central pocket. Although these structures have provided detailed mechanistic insights, the structural features in FS enzymes dictating the synthesis of either β-(2→6) or β-(2→1) linkages, degree and type of branching, and fructan molecular mass remain to be identified.Keywords
This publication has 157 references indexed in Scilit:
- Mutational analysis of the role of calcium ions in the Lactobacillus reuteri strain 121 fructosyltransferase (levansucrase and inulosucrase) enzymesFEBS Letters, 2005
- Site‐directed mutagenesis study of the three catalytic residues of the fructosyltransferases of Lactobacillus reuteri 121FEBS Letters, 2004
- The fully conserved Asp residue in conserved sequence region I of the α‐amylase family is crucial for the catalytic site architecture and activityFEBS Letters, 2003
- Relationship of sequence and structure to specificity in the α-amylase family of enzymesBiochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology, 2001
- SWISS‐MODEL and the Swiss‐Pdb Viewer: An environment for comparative protein modelingElectrophoresis, 1997
- A circularly permuted α‐amylase‐type α/β‐barrel structure in glucan‐synthesizing glucosyltransferasesFEBS Letters, 1996
- Molecular genetic analysis of the catalytic site of Streptococcus mutans glucosyltransferasesBiochemical and Biophysical Research Communications, 1992
- Isolation and characterization of levansucrase-encoding gene from Bacillus amyloliquefaciensGene, 1990
- An Inulin-like Fructan Produced by Streptococcus mutans, Strain JC2.Acta Chemica Scandinavica, 1974
- FACTORS AFFECTING MOLECULAR WEIGHT OF ENZYMATICALLY SYNTHESIZED DEXTRANJournal of the American Chemical Society, 1953