Zhang Ying, Xiang Ye, Van Etten James L, Rossmann Michael G
Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907, USA.
Structure. 2007 Sep;15(9):1031-9. doi: 10.1016/j.str.2007.07.006.
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.
草履虫小球藻病毒-1编码至少五种假定的糖基转移酶，它们可能参与病毒主要衣壳蛋白聚糖成分的合成。其中一种糖基转移酶（A64R）的1.6埃晶体结构具有混合的α/β折叠，包含一个由α螺旋包围的中央六链β折叠。A64R与UDP、CMP或GDP复合的晶体结构表明，在Mn(2+)存在的情况下，只有UDP与A64R结合，这与其与利用UDP作为糖载体的糖基转移酶的高度结构相似性一致。A64R、UDP-葡萄糖和Mn(2+)复合物的结构表明，当与配体形成氢键时发生了最大的构象变化。与UDP-葡萄糖不同，UDP-半乳糖和UDP-GlcNAc不与A64R结合，表明UDP-葡萄糖具有选择性结合。因此，UDP-葡萄糖很可能是A64R的糖供体，这与病毒主要衣壳蛋白聚糖中存在葡萄糖一致。
