Solution structure of Alg13: the sugar donor subunit of a yeast N-acetylglucosamine transferase.
The solution structure of Alg13, the glycosyl donor-binding domain of an important bipartite glycosyltransferase in the yeast Saccharomyces cerevisiae, is presented. This glycosyltransferase is unusual in that it is active only in the presence of a binding partner, Alg14. Alg13 is found to adopt a unique topology among glycosyltransferases. Rather than the conventional Rossmann fold found in all GT-B enzymes, the N-terminal half of the protein is a Rossmann-like fold with a mixed parallel and antiparallel beta sheet. The Rossmann fold of the C-terminal half of Alg13 is conserved. However, although conventional GT-B enzymes usually possess three helices at the C terminus, only two helices are present in Alg13. Titration of Alg13 with both UDP-GlcNAc, the native glycosyl donor, and a paramagnetic mimic, UDP-TEMPO, shows that the interaction of Alg13 with the sugar donor is primarily through the residues in the C-terminal half of the protein.
Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA.
Xu
X
Wang
Thomas
T
Weldeghiorghis
Guofeng
G
Zhang
Barbara
B
Imperiali
James H
JH
Prestegard
D000595:Amino Acid Sequence; D001665:Binding Sites; D003497:Cyclic N-Oxides / Q000737:chemistry; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017351:N-Acetylglucosaminyltransferases / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D014530:Uridine Diphosphate / Q000031:analogs & derivatives / Q000737:chemistry; D014537:Uridine Diphosphate N-Acetylglucosamine / Q000737:chemistry
D003497:Cyclic N-Oxides; D008024:Ligands; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; C530748:UDP-TEMPO; D014537:Uridine Diphosphate N-Acetylglucosamine; D014530:Uridine Diphosphate; C506082:Alg13 protein, S cerevisiae; D017351:N-Acetylglucosaminyltransferases