Structure and surface exposure of protein IIs of Neisseria gonorrhoeae JS3
Structure and surface exposure of protein IIs of Neisseria gonorrhoeae JS3
复制标题
淋病奈瑟菌 JS3 蛋白 II 的结构和表面暴露
作者：
R. C. Judd
淋病奈瑟氏球菌JS 3的菌落，每个带有占优势的蛋白II（PII）类型，来自祖先透明菌落。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳鉴定和分离了五种不同的PII。从未标记的全细胞凝胶和含有表面放射性碘标记细菌裂解物的凝胶中切下PII条带。这些进行了α-糜蛋白酶消化和二维肽图谱，这使得两个PI的一级结构的比较和分子的表面暴露区域的识别。结果表明，PIIs在结构上与蛋白I或蛋白III无关，但彼此密切相关，共享α-糜蛋白酶产生的肽的约三分之二。其余三分之一的肽随每个PII而变化，导致分子的独特部分暴露在细菌表面。然而，可变肽并不总是在暴露的肽中，这表明PII中的结构差异发生在PII分子的离散位点（或多个位点），而不是随机地遍及蛋白质。这样的改变可能导致分子的远距离的、不变的部分暴露于表面，可能是通过构象变化。因此，这些细菌可以在疾病过程中向宿主呈现各种新的免疫决定簇位点。
Colonies of Neisseria gonorrhoeae JS3, each bearing a predominate protein II (PII) type, were derived from a progenitor transparent colony. Five distinct PIIs were identified and isolated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The PII bands were excised from gels of unlabeled whole cells and from gels containing lysates of surface-radioiodinated bacteria. These were subjected to alpha-chymotrypsin digestion and two-dimensional peptide mapping, which allowed for a comparison of both the primary structures of the PIIs and the identification of surface-exposed regions of the molecules. The results demonstrated that PIIs are unrelated to either Protein I or Protein III in structure but are closely related to one another, sharing about two-thirds of the peptides generated by alpha-chymotrypsin. The remaining third of the peptides varied with each PII, resulting in unique portions of the molecule being exposed on the bacterial surface. However, the variable peptides were not always among the exposed peptides, suggesting that the structural differences in the PIIs occur at a discrete site (or sites) of the PII molecule and not randomly throughout the protein. Such alterations can result in the exposure of distant, nonvariant portions of the molecule to the surface, perhaps by conformational changes. These bacteria can thus present a variety of new immunodeterminant sites to the host during the course of disease.