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

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.