The catalytic mechanism of UDP-GlcNAc:mannoside N-acetylglucosaminyltransferases I and II
Abstract
The covalent modification of proteins with oligosaccharides at selected asparagine residues is termed N-glycosylation. The formation of N-glycans is often crucial for the proper synthesis and function of the respective glycoprotein. Most N-linked oligosaccharides on mammalian glycoproteins are either of the oligomannosidic or the complex type. The key enzymes for the conversion of oligomannosidic N-glycans into complex-type N-linked oligosaccharides are N -acetylglucosaminyltransferases I (GnT-I) and II (GnT-II). In spite of the physiological significance of GnT-I and GnT-II, the catalytic mechanism of these enzymes is only poorly understood. This project aims at a detailed molecular characterisation of the enzymatic properties of GnT-I and GnT-II. Our main approach is based on site-directed mutagenesis of recently cloned GnT-I and GnT-II DNAs. We will mutate amino acid residues of the enzymes that are strictly conserved from plants to man. The mutant cDNAs will then be expressed in a heterologous system. Finally, the catalytic properties of the corresponding proteins will be bona fide characterised. This project will substantially improve the current knowledge of glycosyltransferase action and be a first step towards the rational design of novel inhibitors which may prove valuable tools to modify the N-glycosylation machinery of eukaryotic cells in vivo.
keywords glycosyltransferase glycobiology enzyme mechanism protein engineering recombinant glycoproteins
Publikationen
Structural and functional features of glycosyltransferases.
Autoren: Breton, C; Mucha, J; Jeanneau, C Jahr: 2001
Journal articles
Structure-function analysis of rabbit UDP-GlcNAc-N-acetylglucosaminyltransferase I.
Autoren: Mucha, J., Scanziani, M., Svoboda, B., Zoihsl, O., Hartmann, B., Schachter, H., Rini, J., Glössl, J., Mach, L. Jahr: 2001
Conference & Workshop proceedings, paper, abstract
Biosynthesis of glycoprotein N-glycans in plants
Autoren: Glössl, J. Jahr: 2003
Conference & Workshop proceedings, paper, abstract
Two closely related forms of UDP-GlcNAc: alpha6-D-mannoside beta1,2-N-acetylglucosaminyltransferase II occur in the clawed frog Xenopus laevis.
Autoren: Mucha, J; Svoboda, B; Kappel, S; Strasser, R; Bencur, P; Fröhwein, U; Schachter, H; Mach, L; Glössl, J Jahr: 2002
Journal articles
Project staff
Josef Glößl
Em.O.Univ.Prof. Dr.phil. Josef Glößl
josef.gloessl@boku.ac.at
Tel: +43 1 47654-94322
Project Leader
01.06.2000 - 31.05.2003
Lukas Mach
Univ.Prof. Dipl.-Ing. Dr.nat.techn. Lukas Mach
lukas.mach@boku.ac.at
Tel: +43 1 47654-94065, 94360
Project Staff
01.06.2000 - 31.05.2003
BOKU partners
External partners
Department of Biochemistry, Hospital for Sick Children
none
partner