MODE OF ACTION OF STAPHYLOCOCCAL LEUKOCIDIN AND gamma-HEMOLYSIN

葡萄球菌γ-溶血素由Hlg1(或Luk F)和Hlg2组成，协同裂解人红细胞。由于γ-溶血素在裂解前会引起人红细胞的肿胀，我们用聚乙二醇作渗透保护剂研究了该毒素的成孔性质，并测定了其功能孔径。为了阐明γ-溶血素形成的膜孔的分子结构，我们用2%十二烷基硫酸钠溶解孔复合体，用蔗糖梯度离心法对其进行纯化，并在电子显微镜下观察纯化后的孔复合体。我们的数据表明，Hlg1和Hlg2组分以1：1的摩尔比组装成一个200 kDa的环状复合体，形成一个功能直径为2.1-2.4 nm的膜孔。葡萄球菌杀白素由Luks和LukF组成，它裂解人和兔多形核白细胞和兔红细胞。在这里，我们研究了杀白素的成孔特性和杀白素孔的分子结构。(1)白血球杀菌素可引起兔红细胞钾离子外流和裂解前细胞肿胀。然而，当细胞外间隙中存在流体力学直径大于或等于&gt；2.1 nm的聚乙二醇时，肿胀的细胞不会发生最终的溶解。(2)电子显微镜观察表明，杀白素在人多形核白细胞和兔红细胞上形成外径为9 nm、内径为3 nm的环状结构。(3)从靶细胞中分离出大小相同的环状结构，它们含有LuK和LukF，摩尔比为1：1。(4)单个环状毒素复合体的分子大小为205 kDa。这些结果表明，LuKs和LukF在靶细胞上组装成约200 kDa的环状低聚物，形成功能直径约为

Staphylococcal gamma-hemolysin consists of Hlg1 (or Luk F) and Hlg2, which cooperatively lyze human erythrocytes. Since gamma-hemolysin caused swelling of human erythrocytes before lysis, we studied pore-forming nature of the toxin by use of polyethylene glycols as osmotic protectants and determined the functional diameter of the pore. To elucidate the molecular architecture of the membrane pore formed by gamma-hemolysin, we solubilized the pore complex with 2 % sodium dodecyl sulfate, purified it by sucrose gradient centrifugation, and observed the purified pore complex under an electron microscope. Our data showed that the Hlg1 and the Hlg2 components assemble into a ring-shaped 200 kDa complex in a molar ratio of 1 : 1, forming a membrane pore with a functional diameter of 2.1-2.4 nm.Staphylococcal leukocidin consists of LukS and LukF, which lyse human and rabbit polymorphonuclear leukocytes and rabbit erythrocytes. Here we studied the pore-forming properties of leukocidin and the molecular architecture of the leukocidin pore. (1) Leukocidin caused an efflux ofpotassium ions from rabbit erythrocytes and swelling of the cells before lysis. However, ultimate lysis of the swollen cells did not occur when polyethylene glycols with hydrodynamic diameters of <greater than or equal> 2.1 nm were present in the extracellular space. (2) Electron microscopy showed that the leukocidin formed a ring-shaped structure with outer and inner diameters of 9 and 3 nm, respectively, on human polymorphonuclear leukocytes and rabbit erythrocytes. (3) Ring-shaped structures of the same dimensions were isolated from the target cells, and they contained LukS and LukF in a molar ratio of 1 : 1. (4) A single ring-shaped toxin complex had a molecular size of 205 kDa. These results indicated that LukS and LukF assemble into a ring-shaped oligomer of approximately 200 kDa on the target cells, forming a membrane pore with a functional diameter of approximat