Department of Biology, Institute of Microbiology, ETH Zürich, Wolfgang-Pauli-Strasse 10, Zürich, Switzerland.
Glycobiology. 2011 Jan;21(1):45-54. doi: 10.1093/glycob/cwq130. Epub 2010 Sep 16.
A number of proteobacteria carry the genetic information to perform N-linked glycosylation, but only the protein glycosylation (pgl) pathway of Campylobacter jejuni has been studied to date. Here, we report that the pgl gene cluster of Campylobacter lari encodes for a functional glycosylation machinery that can be reconstituted in Escherichia coli. We determined that the N-glycan produced in this system consisted of a linear hexasaccharide. We found that the oligosaccharyltransferase (OST) of C. lari conserved a predominant specificity for the primary sequence D/E-X(-1)-N-X(+1)-S/T (where X(-1) and X(+1) can be any amino acid but proline). At the same time, we observed that this enzyme exhibited a relaxed specificity toward the acceptor site and modified asparagine residues of a protein at sequences DANSG and NNNST. Moreover, C. lari pgl glycosylated a native E. coli protein. Bacterial N-glycosylation appears as a useful tool to establish a molecular description of how single-subunit OSTs perform selection of glycosyl acceptor sites.
一些变形菌携带进行 N 连接糖基化的遗传信息，但迄今为止，仅研究了空肠弯曲菌的蛋白质糖基化 (pgl) 途径。在这里，我们报告了弯曲杆菌拉里的 pgl 基因簇编码了一种可在大肠杆菌中重建的功能性糖基化机制。我们确定该系统产生的 N-聚糖由线性六糖组成。我们发现，拉里弯曲杆菌的寡糖基转移酶 (OST) 对主要序列 D/E-X(-1)-N-X(+1)-S/T （其中 X(-1) 和 X(+1) 可以是任何氨基酸，但脯氨酸除外）具有主要特异性。同时，我们观察到该酶对接受体部位和蛋白质中 DANSG 和 NNNST 序列的天冬酰胺残基具有宽松的特异性。此外，C. lari pgl 糖基化了天然的大肠杆菌蛋白。细菌 N-糖基化似乎是一种有用的工具，可以建立对单亚基 OST 如何选择糖基化接受体部位的分子描述。
