Time lapse AFM on vesicle formation from mixed lipid bilayers induced by the membrane–active peptide melittin

Abstract

Melittin is a model system for the action of antimicrobial peptides which are potential candidates for novel antibiotics. We investigated the membrane lysis effect of melittin on phase-separated supported lipid bilayers (DOPC–DPPC) by atomic force microscopy. AFM images show that the peptide first forms defects at the interface between the two lipid phases and then degrades preferentially the liquid-phase DOPC-enriched domains. Vesicular structures of 10–20 nm radius were observed to form, suggesting a mixed carpet–toroidal model mechanism for the resolved action of melittin.