Polysaccharide-synthesizing glycosyltransferases and carbohydrate binding modules: the case of starch synthase III.

DIEGO FABIAN GOMEZ CASATI; MARTIN, M.; BUSI, M. V.

PROTEIN AND PEPTIDE LETTERS

BENTHAM SCIENCE PUBL LTD

Lugar: Oak Park; Año: 2013 p. 856 - 863

0929-8665

Glycosyltransferases (GTs) are a ubiquitous group of enzymes that catalyze thetransfer of sugar moieties from activated donor molecules to specific acceptormolecules, forming glycosidic bonds. Nucleotide-sugars, lipid phosphate sugars andphosphate sugars can act as activated donor molecules while acceptor substrates involvecarbohydrates, proteins, lipids, DNA and also, numerous small molecules (i. e.antibiotics, flavonols, steroids). GTs enzyme families are very ancient. They arefounded in all the three domains of life and display three different folds (named GT-A,GT-B and GT-C) which are a variant of a common / scaffold. In addition, severalGTs contain an associated non-catalytic carbohydrate binding module (CBM) that couldbe critical for enzyme activity.This work reviews the current knowledge on the GTs structures and functionsand highlights those enzymes that contain CBMs, particularly starch binding domains(SBDs). In addition, we also focus on A. thaliana starch synthase III enzyme, from theGT-5 family. This protein has a GT-B fold, and contains in its N-terminal region threein tandem SBDs, which are essential for the regulation of enzyme activity.