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

Area of Science:

• Biophysics
• Biochemistry
• Materials Science

Background:

• Antimicrobial peptides (AMPs) are promising candidates for novel antibiotics.
• Melittin serves as a model system to study AMP mechanisms.
• Understanding peptide-membrane interactions is crucial for drug development.

Purpose of the Study:

• To investigate the membrane lysis effect of melittin on phase-separated supported lipid bilayers.
• To elucidate the mechanism of melittin's action at the lipid bilayer interface.

Main Methods:

• Utilized atomic force microscopy (AFM) to visualize peptide-membrane interactions.
• Employed phase-separated supported lipid bilayers composed of DOPC-DPPC.
• Analyzed AFM images to observe structural changes and peptide-induced defects.

Main Results:

• Melittin initially formed defects at the interface between lipid phases.
• The peptide preferentially degraded liquid-phase, DOPC-enriched domains.
• Observed formation of vesicular structures with radii of 10-20 nm.

Conclusions:

• Melittin's action on lipid bilayers involves targeted domain degradation.
• A mixed carpet-toroidal model is proposed to explain melittin's mechanism.
• Findings contribute to understanding AMPs for potential antibiotic applications.