Finck-Barbançon V, Duportail G, Meunier O, Colin D A
Laboratoire de Toxinologie Bactérienne, Faculté de Médecine, Université Louis Pasteur, Strasbourg, France.
Biochim Biophys Acta. 1993 Oct 20;1182(3):275-82. doi: 10.1016/0925-4439(93)90069-d.
The effects of the Staphylococcus aureus leukocidin (PVL), a two-component non-hemolytic toxin, were investigated on the membrane permeability of human polymorphonuclear leukocytes (PMNs). In the absence of extracellular Ca2+, the fluorescence of ethidium bromide added to the extracellular medium increased after PVL application in a concentration-dependent manner and no variations in the free intracellular [Ca2+] of Fura2-loaded PMNs were detected. In the presence of extracellular Ca2+, the fluorescence of ethidium was not modified but the free intracellular [Ca2+] of PMNs increased after application of PVL in a concentration-dependent manner. The time lag observed before an increase in the ethidium fluorescence was longer than the time lag observed before a Fura2 fluorescence increase. Simultaneous recordings of the two probes fluorescence variations have shown the protective effect of Ca2+ and Zn2+ and the closing of the pore by 50 mM Ca2+ or 2 mM Zn2+. Moreover, the effect of Ca2+ could be reversed by the addition of EGTA. In the presence of 1 mM extracellular Ca2+ or 0.8 mM extracellular Zn2+, the pore induced by PVL had an ionic size allowing Ca2+, Mn2+, Zn2+ and Mg2+ fluxes. The addition of antibodies against either component of PVL inhibits the permeabilization provoked by the toxin even after it was initiated. It is concluded that leukocidin from S. aureus is a pore-forming toxin which, under physiological conditions ([Ca2+] = 1 to 1.5 mM), provokes the formation of an ion-sized pore inducing an increase in the free intracellular Ca2+ which may activate PMN functions.
研究了金黄色葡萄球菌白细胞毒素（PVL，一种双组分非溶血毒素）对人多形核白细胞（PMN）膜通透性的影响。在无细胞外Ca2+的情况下，加入细胞外培养基中的溴化乙锭荧光在应用PVL后呈浓度依赖性增加，且未检测到Fura2负载的PMN细胞内游离[Ca2+]有变化。在有细胞外Ca2+存在时，溴化乙锭荧光未改变，但应用PVL后PMN细胞内游离[Ca2+]呈浓度依赖性增加。观察到溴化乙锭荧光增加前的时间延迟比Fura2荧光增加前的时间延迟更长。两种探针荧光变化的同步记录显示了Ca2+和Zn2+的保护作用以及50 mM Ca2+或2 mM Zn2+对孔的封闭作用。此外，加入EGTA可逆转Ca2+的作用。在存在1 mM细胞外Ca2+或0.8 mM细胞外Zn2+时，PVL诱导的孔具有允许Ca2+、Mn2+、Zn2+和Mg2+通量的离子大小。加入针对PVL任一成分的抗体可抑制毒素引发的通透性，即使在通透性已开始后也是如此。结论是金黄色葡萄球菌白细胞毒素是一种成孔毒素，在生理条件下（[Ca2+]=1至1.5 mM），可引发离子大小孔的形成，导致细胞内游离Ca2+增加，这可能激活PMN功能。
