INACTIVATION OF GAMMA-HEMOLYSIN H-GAMMA-II COMPONENT BY ADDITION OF MONOSIALOGANGLIOSIDE GM1 TO HUMAN ERYTHROCYTE

The Staphylococcal toxins leukocidin and gamma-hemolysin consist of two protein components: F and S in leukocidin and HgammaI and HgammaII in gamma-hemolysin. The two toxins share one component (F = HgammaI). We found that the HgammaII component was completely inactivated by the addition of monosialoganglioside G(M1) at the molar ratio of 1 : 1. Disialogangliosides G(D1a) and G(D1b) had little effect on the inactivation of HgammaII. The molar ratios of G(D1a) and G(D1b) to HgammaII needed for maximum inactivation were 30:1 and 100:1, respectively. Related glycolipids caused little if any inactivation. HgammaII bound to G(M1) to form HgammaII-G(M1) complexes. Analysis of the intrinsic aromatic amino acid fluorescence in HgammaII and HgammaII-G(M1) with 280 nm as the excitation wavelength showed that G(M1) in the complex reduced the fluorescence intensity of HgammaII by 12% without changing the wavelength of maximum emission (325 nm). We concluded that G(M1) is a receptor of the HgammaII component on human erythrocytes and that HgammaII takes on a different conformation when it binds to G(M1).