Title
Structure-function relationships of glucansucrase and fructansucrase enzymes from lactic acid bacteria
Author
van Hijum, S.A.F.T.
Kralj, S.
Ozimek, L.K.
Dijkhuizen, L.
van Geel-Schutten, G.H.
TNO Kwaliteit van Leven
Publication year
2006
Abstract
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 a-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 polysacchande 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. Copyright © 2006, American Society for Microbiology. All Rights Reserved.
Subject
Nutrition
Food technology
bacterial enzyme
calcium ion
fructan
fructan sucrase
glucan
glucan sucrase
oligosaccharide
polymer
signal peptide
sucrase
unclassified drug
amino acid substitution
binding site
catalysis
enzyme activity
enzyme mechanism
enzyme structure
gene mutation
lactic acid bacterium
nomenclature
nonhuman
nucleotide sequence
review
synthesis
Amino Acid Sequence
Bacterial Proteins
Fructans
Glycosyltransferases
Gram-Positive Bacteria
Lactic Acid
Molecular Sequence Data
Protein Conformation
Structure-Activity Relationship
Sucrase
Bacteria (microorganisms)
Negibacteria
Posibacteria
To reference this document use:
http://resolver.tudelft.nl/uuid:9cc8b66e-f75a-4311-8757-2c492121f274
DOI
https://doi.org/10.1128/mmbr.70.1.157-176.2006
TNO identifier
239147
ISSN
1092-2172
Source
Microbiology and Molecular Biology Reviews, 70 (1), 157-176
Document type
article