Biosynthesis glycosyltransferases

Many different glycosyltransferase activities involved in higher plant wall biosynthesis have been identified in cell free membrane fractions, but in only a few cases has glycosyltransferase activity been retained in detergent-solubilized preparations, and in even fewer cases have any purified polypeptides been identified as plant cell wall glycosyltransferases (29,33). 

Borisova, S., Zhao, L., Melancon, C.E. et al. (2004) Characterization of the glycosyltransferase activity of desVII analysis of and implications for the biosynthesis of macrolide antibiotics. Journal of the American Chemical... 

Most of the glycosyltransferases involved in the biosynthesis of gangliosides are integral transmembrane proteins and catalyse the transfer of... 

The condensation step is catalyzed by the glycosyltransferase SpcF. Further enzyme-catalyzed oxidation is probably needed for the introduction of the hemiketal linkage between cyclitol and sugar units. The SpcY enzyme, which has a similar counterpart, HygY, among the /lyg-cluster encoded proteins (see Section 2.2.4.3.1), is a candidate enzyme for this reaction. SpcY is a member of the radical SAM superfamily of proteins and relatives of SpcY have been found before all in connection with molybdenum-cofactor biosynthesis but to our knowledge no details of the mechanism involved is known for those. 

In summary, different strategies for the combinatorial biosynthesis of oHgosaccharides have been established successfully. However, some systems are Hmited mostly to bacterial glycosyltransferases because of their better expression in E. coli. The yeast systems seem to be better suited for expression of mammahan glycosyltransferases however, it remains to be demonstrated if they can be also utilized as living factories for the production of oligosaccharides. 

Jones, P. et al., UGT73C6 and UGT78D1 — glycosyltransferases involved in fiavonol glycoside biosynthesis in Arabidopsis thaliana. J. Biol. Chem., 278, 43910, 2003. 

The incubation mixture for the biosynthesis of glycosphingolipids usually includes an enzyme preparation, a glycosyl donor, a glycolipid acceptor, a detergent, and metal ions. Most of the glycosyltransferases are membrane bound and are usually associated with the microsomal... 

The biosynthesis of O-Iinked oligosaccharides follows a different scheme. In contrast with the dolichyl pyrophosphate-mediated synthesis of N-linked oligosaccharides, the glycosyltransferases necessary for the synthesis of O-linked oligosaccharides are located in the Golgi apparatus [9]. Monosaccharide residues are added sequentially to the growing oligosaccharide chain. 

For example, the biosynthesis of alginate involves GDP-mannuronic acid (GDP-ManA) as NDP-Glx, bactoprenol as the lipid, and a glycosyltransferase that inserts a second mannuronate residue (as Z). 

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