Department of Life Sciences, Ben Gurion University of the Negev, Beersheva, Israel.
Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA.
Trends Biochem Sci. 2018 Jan;43(1):10-17. doi: 10.1016/j.tibs.2017.10.008. Epub 2017 Nov 25.
In the three domains of life, lipid-linked glycans contribute to various cellular processes ranging from protein glycosylation to glycosylphosphatidylinositol anchor biosynthesis to peptidoglycan assembly. In generating many of these glycoconjugates, phosphorylated polyprenol-based lipids are charged with single sugars by polyprenol phosphate glycosyltransferases. The resultant substrates serve as glycosyltransferase donors, complementing the more common nucleoside diphosphate sugars. It had been accepted that these polyprenol phosphate glycosyltransferases acted similarly, given their considerable sequence homology. Recent findings, however, suggest that matters may not be so simple. In this Opinion we propose that the stereochemistry of sugar addition by polyprenol phosphate glycosyltransferases is not conserved across evolution, even though the GT-A fold that characterizes such enzymes is omnipresent.
在生命的三个领域中，脂连接聚糖有助于各种细胞过程，从蛋白质糖基化到糖基磷脂酰肌醇锚生物合成再到肽聚糖组装。在生成许多这些糖缀合物时，通过聚异戊二烯磷酸糖基转移酶将磷酸化的多萜醇基脂质加载到单糖上。所得的底物充当糖基转移酶供体，补充了更常见的核苷二磷酸糖。鉴于其相当大的序列同源性，人们已经接受了这些多萜醇磷酸糖基转移酶的作用相似。然而，最近的发现表明情况可能并非如此简单。在本观点中，我们提出，即使特征此类酶的 GT-A 折叠无处不在，但通过聚异戊二烯磷酸糖基转移酶添加糖的立体化学在进化过程中并不保守。
