y-Hemolysin oligomeric structure and effect of its formation on supported lipid bilayers: an AFM investigation

y-Hemolysins are bicomponent ?-barrel pore forming toxins produced by Staphylococcus aureus as water-soluble monomers, which assemble into oligomeric pores on the surface of lipid bilayers. Here, after investigating the oligomeric structure of ?-hemolysins on supported lipid bilayers (SLBs) by atomic force microscopy (AFM), we studied the effect produced by this toxin on the structure of SLBs. We found that oligomeric structures with different number of monomers can assemble on the lipid bilayer being the octameric form the stablest one. Moreover, in this membrane model we found that ?-hemolysins can form clusters of oligomers inducing a curvature in the lipid bilayer, which could probably enhance the aggressiveness of these toxins at high concentrations.