Virji M, Stimson E, Makepeace K, Dell A, Morris H R, Payne G, Saunders J R, Moxon E R
Department of Peadiatrics, University of Oxford, John Radcliffe Hospital, UK.
Ann N Y Acad Sci. 1996 Oct 25;797:53-64. doi: 10.1111/j.1749-6632.1996.tb52949.x.
Neisseria meningitidis pili are filamentous protein structures that are essential adhesins in capsulate bacteria. Pili of adhesion variants of meningococcal strain C311 contain glycosyl residues on pilin (PilE), their major structural subunit. Recent studies have shown that a novel O-linked trisaccharide substituent, not previously found as a constituent of glycoproteins, is present within a peptide spanning amino acid residues 50 to 73 of the PilE molecule. The structure was shown to be Gal beta 1-4 Gal alpha 1-3 diacetamidotrideoxyhexose which is directly attached to pilin. Pilins derived from galactose epimerase (galE) mutants lack the digalactosyl moiety, but retain the diacetamidotrideoxyhexose substitution. These studies confirm our previous observations that meningococcal pili are glycosylated and provide the first structural evidence for the presence of covalently linked carbohydrate on pili. We have identified a completely novel protein/carbohydrate linkage on a multimeric protein that is an essential virulence determinant in N. meningitidis.
脑膜炎奈瑟菌菌毛是丝状蛋白质结构，是荚膜细菌中的重要黏附素。脑膜炎球菌C311菌株黏附变体的菌毛在菌毛蛋白（PilE）（其主要结构亚基）上含有糖基残基。最近的研究表明，在PilE分子中跨越氨基酸残基50至73的肽段内存在一种新型的O-连接三糖取代基，此前未发现其作为糖蛋白的组成成分。该结构显示为Galβ1-4Galα1-3二乙酰氨基脱氧己糖，它直接连接在菌毛蛋白上。来自半乳糖表异构酶（galE）突变体的菌毛蛋白缺乏二半乳糖基部分，但保留了二乙酰氨基脱氧己糖取代基。这些研究证实了我们之前关于脑膜炎球菌菌毛被糖基化的观察结果，并为菌毛上存在共价连接的碳水化合物提供了首个结构证据。我们在一种多聚体蛋白上鉴定出了一种全新的蛋白质/碳水化合物连接方式，该蛋白是脑膜炎奈瑟菌中一种重要的毒力决定因素。
