Structure and function of a chlorella virus-encoded glycosyltransferase.
Paramecium bursaria chlorella virus-1 encodes at least five putative glycosyltransferases that are probably involved in the synthesis of the glycan components of the viral major capsid protein. The 1.6 A crystal structure of one of these glycosyltransferases (A64R) has a mixed alpha/beta fold containing a central, six-stranded beta sheet flanked by alpha helices. Crystal structures of A64R, complexed with UDP, CMP, or GDP, established that only UDP bound to A64R in the presence of Mn(2+), consistent with its high structural similarity to glycosyltransferases which utilize UDP as the sugar carrier. The structure of the complex of A64R, UDP-glucose, and Mn(2+) showed that the largest conformational change occurred when hydrogen bonds were formed with the ligands. Unlike UDP-glucose, UDP-galactose and UDP-GlcNAc did not bind to A64R, suggesting a selective binding of UDP-glucose. Thus, UDP-glucose is most likely the sugar donor for A64R, consistent with glucose occurring in the virus major capsid protein glycans.
Zhang
Ying
Y
Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907, USA.
Xiang
Ye
Y
Van Etten
James L
JL
Rossmann
Michael G
MG
D000818:Animals; D006031:Glycosylation; D016695:Glycosyltransferases / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D010247:Paramecium / Q000821:virology*; D011487:Protein Conformation; D014780:Viruses / Q000201:enzymology*
D016695:Glycosyltransferases