Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom.
J Bacteriol. 2012 May;194(9):2355-62. doi: 10.1128/JB.00042-12. Epub 2012 Mar 2.
The Gram-negative bacterium Campylobacter jejuni encodes an extensively characterized N-linked protein glycosylation system that modifies many surface proteins with a heptasaccharide glycan. In C. jejuni, the genes that encode the enzymes required for glycan biosynthesis and transfer to protein are located at a single pgl gene locus. Similar loci are also present in the genome sequences of all other Campylobacter species, although variations in gene content and organization are evident. In this study, we have demonstrated that only Campylobacter species closely related to C. jejuni produce glycoproteins that interact with both a C. jejuni N-linked-glycan-specific antiserum and a lectin known to bind to the C. jejuni N-linked glycan. In order to further investigate the structure of Campylobacter N-linked glycans, we employed an in vitro peptide glycosylation assay combined with mass spectrometry to demonstrate that Campylobacter species produce a range of structurally distinct N-linked glycans with variations in the number of sugar residues (penta-, hexa-, and heptasaccharides), the presence of branching sugars, and monosaccharide content. These data considerably expand our knowledge of bacterial N-linked glycan structure and provide a framework for investigating the role of glycosyltransferases and sugar biosynthesis enzymes in glycoprotein biosynthesis with practical implications for synthetic biology and glycoengineering.
空肠弯曲菌是一种革兰氏阴性细菌，它编码了一种经过广泛研究的 N 连接蛋白糖基化系统，该系统可以用七糖聚糖修饰许多表面蛋白。在空肠弯曲菌中，编码糖生物合成和蛋白转移所需酶的基因位于单个 pgl 基因座上。类似的基因座也存在于所有其他弯曲菌属物种的基因组序列中，尽管基因内容和组织的变化是明显的。在这项研究中，我们已经证明，只有与空肠弯曲菌密切相关的弯曲菌属物种才能产生与空肠弯曲菌 N 连接聚糖特异性抗血清和已知与空肠弯曲菌 N 连接聚糖结合的凝集素相互作用的糖蛋白。为了进一步研究弯曲菌 N 连接聚糖的结构，我们采用了体外肽糖基化测定结合质谱的方法，证明弯曲菌属物种产生了一系列结构不同的 N 连接聚糖，其糖残基数量（五糖、六糖和七糖）、分支糖的存在以及单糖含量存在差异。这些数据大大扩展了我们对细菌 N 连接聚糖结构的认识，并为研究糖基转移酶和糖生物合成酶在糖蛋白生物合成中的作用提供了框架，这对合成生物学和糖工程具有实际意义。
