Five structural classes of major outer membrane proteins in Neisseria meningitidis
Five structural classes of major outer membrane proteins in Neisseria meningitidis
复制标题
脑膜炎奈瑟菌主要外膜蛋白的五种结构类别
作者：
C. Tsai;C. Frasch;L. F. Mocca
迄今为止，B 组脑膜炎奈瑟菌根据抗原性不同的主要外膜蛋白被细分为 15 种蛋白血清型。大多数血清型的外膜含有三种或四种主要蛋白质。通过胰凝乳蛋白酶 125I 肽图谱对来自原型菌株以及六种非血清分型菌株的这些主要蛋白质进行了比较结构分析。首先使用 Laemmli 系统通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分离每种血清型的主要外膜蛋白。将凝胶切片内的各个蛋白质进行放射性碘标记并用胰凝乳蛋白酶消化，然后通过电泳和纤维素薄层板上的层析分离它们的 125 I-肽。通过放射自显影获得的肽图被分为五种不同的结构类别，其与蛋白质的表观分子量相关，即46+/-1K、41+/-1K、38+/-1K、33+/-1K和28+/-1K。菌株内的每个主要外膜蛋白都具有明显不同的胰凝乳蛋白酶肽图，表明这些蛋白的一级结构存在显着差异。相比之下，来自不同血清型菌株的相同或非常相似分子量的外膜蛋白具有相似的、有时相同的肽图，表明高度的结构同源性。来自相同结构类别的蛋白质的独特肽通常是亲水性的，而常见肽通常是疏水性的，这表明血清型决定簇存在于主要外膜蛋白的可变亲水区域内。
Group B Neisseria meningitidis is thus far subdivided into 15 protein serotypes based on antigenically different major outer membrane proteins. Most serotypes have three or four major proteins in their outer membranes. Comparative structural analysis by chymotryptic 125I-peptide mapping was performed on these major proteins from the prototype strains as well as from six non-serotypable strains. The major outer membrane proteins from each of the serotypes were first separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis using the Laemmli system. Individual proteins within the gel slices were radioiodinated and digested with chymotrypsin, and then their 125I-peptides were separated by electrophoresis and chromatography on cellulose thin-layer plates. The peptide maps obtained by autoradiography were categorized into five different structural classes which correlated with the apparent molecular weights of proteins, i.e., 46 +/- 1K, 41 +/- 1K, 38 +/- 1K, 33 +/- 1K, and 28 +/- 1K. Each of the major outer membrane proteins within a strain had a distinctly different chymotryptic peptide map, indicating significant differences in the primary structure of these proteins. In contrast, outer membrane proteins of the same or very similar molecular weight from different serotype strains had similar, occasionally identical peptide maps, indicating a high degree of structural homology. The unique peptides from proteins of the same structural classes were often hydrophilic, whereas common peptides were often hydrophobic, suggesting that the serotype determinants reside within the variable hydrophilic regions of major outer membrane proteins.