The mechanism of leukocytolysis and hemolysis of the Staphylococcal leukocidin and gamma-hemolysin

众所周知，在其生物学功能中显示出总体相似性的蛋白质具有彼此相似的一级结构。然而，最近，甚至在一级结构上显示出不同的蛋白质也被报道具有相同的生物学功能和三维结构。以葡萄球菌通道形成毒素为例。金黄色葡萄球菌将杀白细胞素和γ-溶血素（γ-HL）作为水溶性单体分泌到培养基中。杀白细胞素和r-HL分别含有两种单独的和协同的蛋白质组分，LukF和LukS，以及LukF和Hlg 2（或H γ H）.杀白细胞素的LukF和LukS以及γ-HL的LukF和Hlg 2组装成环状复合物，其中LukF与LukS或Hlg 2的摩尔比分别为1：1，在人多形细胞白细胞膜和红细胞膜内。在每种情况下，产生功能直径为2.1-2.5 nm的跨膜孔; ...更多信息 这导致溶解相应的靶细胞。杀白细胞素和γ-HL的细胞特异性分别由LukS和Hlg 2确定。尽管LukS和Hlg 2氨基酸序列之间的总体一致性为72%，但严格限定了各自的细胞特异性。在科学研究资助金（B）支持的一年内，我们阐明了以下证据。[I]葡萄球菌Panton-Valentine杀白细胞素（PVL）基因[lukS-PV-lukF-PV]存在于分离自丝裂霉素C诱导的金黄色葡萄球菌V8（ATCC 49775）的温和噬菌体phiPVL的基因组上[Kaneko et al.，1997. Biosci. Biotechnol. 61，1960- 1962]。在这项研究中，完整的核苷酸序列的phiPVL基因组进行了分析，并attL，attR，和attB位点所需的phiPVL位点特异性整合到宿主染色体也被确定。[II]葡萄球菌γ-溶血素Hlg 2特异性功能所必需的最小片段的鉴定：Hlg 2的5个残基的K1 <23>RLA<127>是葡萄球菌γ-溶血素Hlg 2特异性功能所必需的最小片段。[III]以苏氨酸246位残基为蛋白激酶A磷酸化位点的葡萄球菌杀白细胞素LukS特异性功能最小片段的鉴定：鉴定了负责杀白细胞素LukS特异性功能的最小片段。我们的结论是，5个残基片段I^<242>K^<243>R^<244>S^<245>T^<246>是负责葡萄球菌杀白细胞素的LukS功能的关键片段。[IV]蛋白激酶A对LukS的磷酸化对葡萄球菌杀白细胞素在人多形核白细胞上的LukS特异性功能至关重要[V]葡萄球菌LukF的晶体结构描绘了跨膜通道形成前的构象变化。少

It is well known that the proteins which show gross similarities in their biological function(s) have primary structures which are similar to each other. However, recently even proteins which show dissimilarity in primary structures have been reported to have identical biological functions and the three-dimensional structures. The Staphylococcal channel-forming toxins are taken as an example. Staphylococcus aureus secretes leukocidin and gamma-hemolysin gamma -HL) into a culture medium as water soluble monomers. Leukocidin and r -HL contain two separate and synergistic protein components, LukF and LukS, and LukF and Hlg2 (or H gamma H), respectively. LukF and LukS of leukocidin, and LukF and Hlg2 of gamma -HL assemble into a ring-shaped complexes, in which the molar ratios of LukF to LukS or Hlg2, respectively are both 1 : 1, within human polymorphonuclear leukocyte membranes and erythrocyte membranes. In each case a transmembrane pore results with a functional diameter of 2.1-2.5 nm ; … More this leads to lyse the respective target cell. The cell specificities of leukocidin and gamma -HL are determined by LukS and Hlg2, respectively. Despite the 72% overall identity between the LukS and Hlg2 aminoacid sequences, the respective cell specificities are strictly defined, Within the year suported by Grant-in-Aid for Scientific Research (B), we clarified the following evidences.[I] The staphylococcal Panton-Valentine leukocidin (PVL) genes, [lukS-PV-lukF-PV] exist on the genome of a temperate bacteriophage phiPVL isolated from mitomycin C-induced Staphylococcus aureus V8 (ATCC 49775) [Kaneko et al., 1997. Biosci. Biotechnol. Biochem. 61, 1960-l962]. In this study, the complete nucleotide sequence of the phiPVL genome was analyzed, and the att sites (attL, attR, and attB) required for site-specific integration of phiPVL into the host chromosome were also determined.[II] Identification of the minimum segment essential for the Hlg2-specific function of staphylococcal gamma Hemolysin : The 5-residue K^<23>RLA^<127> of Hlg2 is the minimum segment essential for the Hlg2-specificfunction of staphylococcal gamma-hemolysin.[III] Identification of the minimum segment in which threonine 246 residue is a phosphorylation site by protein kinase A for the LukS-specific function of staphylococcal leukocidin : The minimum segment responsible for the LukS specific funcion of leukocidin was identified. We conclude that the 5-residue segment I^<242>K^<243>R^<244>S^<245>T^<246> is pivotal segment of LukS responsible for the LukS-function of the staphylococcal leukocidin.[IV] The Phosphorylation of LukS by Protein Kinase A is Crucial for the LukS-Specific Function of the Staphylococcal Leukocidin on Human Polymorphonuclear Leukocytes[V] Crystal structure of staphylococcal LukF delineates conformational changes accompaning formation of a transmembrane channel. Less