Institutes of Microbiology, Department of Biology, ETH Zürich, 8093 Zürich, Switzerland.
J Biol Chem. 2011 Oct 7;286(40):35267-74. doi: 10.1074/jbc.M111.277160. Epub 2011 Aug 18.
N-Linked glycosylation is a frequent protein modification that occurs in all three domains of life. This process involves the transfer of a preassembled oligosaccharide from a lipid donor to asparagine side chains of polypeptides and is catalyzed by the membrane-bound oligosaccharyltransferase (OST). We characterized an alternative bacterial pathway wherein a cytoplasmic N-glycosyltransferase uses nucleotide-activated monosaccharides as donors to modify asparagine residues of peptides and proteins. N-Glycosyltransferase is an inverting glycosyltransferase and recognizes the NX(S/T) consensus sequence. It therefore exhibits similar acceptor site specificity as eukaryotic OST, despite the unrelated predicted structural architecture and the apparently different catalytic mechanism. The identification of an enzyme that integrates some of the features of OST in a cytoplasmic pathway defines a novel class of N-linked protein glycosylation found in pathogenic bacteria.
N-连接糖基化是一种常见的蛋白质修饰，发生在所有三个生命领域。这个过程涉及到预先组装的寡糖从脂质供体转移到多肽的天冬酰胺侧链，由膜结合的寡糖基转移酶（OST）催化。我们描述了一种替代的细菌途径，其中细胞质 N-糖基转移酶使用核苷酸激活的单糖作为供体来修饰肽和蛋白质中天冬酰胺残基。N-糖基转移酶是一种反转糖基转移酶，识别 NX（S/T）共识序列。因此，尽管预测的结构架构不同，而且催化机制显然不同，它仍表现出与真核 OST 相似的受体位点特异性。鉴定出一种酶，它在细胞质途径中整合了 OST 的一些特征，定义了一类在致病性细菌中发现的新型 N-连接蛋白糖基化。
