The capsule of Staphy lococcus aureus clinical strains

我们从临床分离的金黄色葡萄球菌荚膜菌株的荚膜层中纯化了一种蛋白（与荚膜多糖相关的蛋白：PAC）。SDS - PAGE测定的糖蛋白分子量为200 kDa。兔抗PAC血清不仅能与蛋白发生反应，还能与提取的荚膜多糖发生反应，但与细胞壁壁壁酸不发生反应。免疫电镜检查显示，抗血清既能与被包膜菌株的细胞壁表面发生反应，也能与胃蛋白酶消化的细胞壁表面发生反应，几乎完全去除细胞壁相关蛋白。这些结果表明，糖蛋白的糖部分可能是荚膜多糖的一部分，蛋白质可能与荚膜层共价结合。该蛋白具有高度疏水性，使被包膜的金黄色葡萄球菌临床菌株具有疏水性表面特征。可以推测，该蛋白可能对细菌在宿主细胞表面的定植有一定作用。

We purified a protein (protein associated with the capsular polysaccharide : PAC) from the capsular layr of clinically isolated encapsulated strains of Staphylococcus aureus. It was a glycoprotein of a molecular size of 200 kDa measured by SDS PAGE.The antiserum raised in a rabbit for PAC reacted not only with the protrein but also with the extracted capsular polysaccharide but not with the cell wall teichoic acid. Immunoelectron microscopic examination of the antiserum treated cell revealed that the antiserum reacted both with the cell wall surface of the encapsulated strain and with the cell wall surface digested with pepsin which removed the cell wall associated proteins almost completely. These results suggested that the sugar moiety of the glycoprotein could be a part of the capsular polysaccharide and the protein could be covalently associated with the capsular layr. The protein had the highly hydrophobic character and it gave the hydrophobic surface character to the encapsulated clinical strains of S.aureus. It can be assumed that the protein may have some roles for the colonization of the bacteria to the host cell surface.