Interaction of the two components of leukocidin from Staphylococcus aureus with human polymorphonuclear leukocyte membranes: sequential binding and subsequent activation.
The sequential interaction between the two components S and F of leukocidin from Staphylococcus aureus and the membrane of human polymorphonuclear neutrophils has been investigated in the presence of 1 mM Ca2+. With 125I-labeled components, it has been shown that binding of the F component occurred only after binding of the S component. The kinetic constants of binding of both components were not statistically different (Kd, approximately 5 nM; Bm, approximately 35,000 molecules per cell), and both Hill coefficients were 1. The application of increasing concentrations of leukocidin provoked a dose-dependent secretion of the granule content, as determined by hexosaminidase and lysozyme activity measurements. Furthermore, the separate perfusion of S and F components on human polymorphonuclear neutrophils deposited on a filter induced secretion of the granules content only when the perfusion of the S component preceded that of the F component. We conclude, therefore, that (i) S-component binding is a prerequisite for F-component binding and for subsequent activation of polymorphonuclear neutrophils and (ii) there is a specific binding site for the S component in the plasma membrane.
Laboratoire de Toxinologie Bactérienne, Faculté de Médecine, Université Louis Pasteur, Strasbourg, France.
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Colin
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Mazurier
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Sire
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Finck-Barbançon
D002118:Calcium / Q000378:metabolism; D006801:Humans; D007956:Leukocidins / Q000378:metabolism / Q000633:toxicity*; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D013211:Staphylococcus aureus / Q000472:pathogenicity*
D007956:Leukocidins; D002118:Calcium