Vesicle budding induced by a pore-forming peptide.

Area of Science:

• Biophysics
• Materials Science

Background:

• Giant unilamellar vesicles (GUVs) are model systems for studying cell membrane mechanics.
• Phase separation in lipid bilayers creates distinct liquid and gel domains, influencing membrane properties.

Purpose of the Study:

• To investigate the mechanism of membrane budding in multicomponent phospholipid vesicles.
• To understand the role of lipid composition, specifically cholesterol, and pore formation in vesicle budding.

Main Methods:

• Utilized giant phospholipid vesicles (GUVs) with phase-separated domains (DOPC and DPPC).
• Induced budding using the pore-forming peptide melittin.
• Employed fluorescence experiments to observe and analyze vesicle budding and domain behavior.
• Investigated the effect of cholesterol on budding dynamics.

Main Results:

• Melittin-induced pores trigger budding in GUVs, extruding material.
• Without cholesterol, melittin selectively binds to liquid domains, forming numerous small, monodisperse buds and shrinking the parent GUV.
• Cholesterol addition leads to domain coalescence and the formation of fewer, larger buds.
• Line tension was identified as crucial for the budding process in these multicomponent membranes.

Conclusions:

• The study elucidates a novel pore-mediated budding mechanism in lipid vesicles.
• Cholesterol content significantly modulates the budding process, affecting bud size and number.
• Line tension is a critical factor governing budding in complex membrane systems.