Lactobacillus helveticus glycosyltransferases: from genes to carbohydrate synthesis

Bioactive carbohydrates are crucial in mediating essential biological processes, and their biosynthesis is an essential aspect to develop for a global view of their biological functions. Lactic acid bacteria display an array of diverse and complex carbohydrates and, therefore, are of particular inte...

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Bibliographic Details
Published in:Glycobiology (Oxford) 2002-05, Vol.12 (5), p.319-327
Main Authors: Jolly, Laure, Newell, John, Porcelli, Ida, Vincent, Sébastien J.F., Stingele, Francesca
Format: Article
Language:English
Subjects:
Carbohydrate Sequence
Carbohydrates - biosynthesis
Chromatography, High Pressure Liquid
Chromatography, Thin Layer
Electrophoresis, Polyacrylamide Gel
Glycosyltransferases - genetics
Key words: enzymatic synthesis of oligosaccharides/eps gene cluster/exopolysaccharide biosynthesis/glycosyltransferases/NMR
Lactobacillus - enzymology
Lactobacillus - metabolism
Lactobacillus helveticus
Molecular Sequence Data
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Summary:Bioactive carbohydrates are crucial in mediating essential biological processes, and their biosynthesis is an essential aspect to develop for a global view of their biological functions. Lactic acid bacteria display an array of diverse and complex carbohydrates and, therefore, are of particular interest. Here we present the identification of a novel exocellular polysaccharide structure and the corresponding gene cluster from Lactobacillus helveticus NCC2745. The development of a glycosyltransferase-specific enzymatic assay allowed the assignment of sugar specificities, which as a general approach will for the future permit a faster and more direct characterization of glycosyltransferase specificities. A model of the biosynthesis of the repeating unit is proposed. EpsE is a phosphoglucosyltransferase initiating the repeating unit biosynthesis by linking a glucose residue to a membrane-associated lipophilic acceptor. EpsF elongates the carbohydrate chain by forming an α(1,3)-Glcp linkage onto the first Glcp, whereas EpsG adds a backbone α(1,6)-Galp onto α-Glcp and EpsH attaches a α(1,6)-Glcp branch onto the first glucose residue. Finally, EpsI would add a β(1,6)-Galp linkage onto α-Glcp terminating the sidechain and EpsJ would terminate the synthesis of the polysaccharides’ repeating unit by forming a β(1,3)-Galp linkage onto α-Galp.
ISSN:0959-6658
1460-2423
DOI:10.1093/glycob/12.5.319