Revisiting peptide amphiphilicity for membrane pore formation

Area of Science:

• Biochemistry
• Membrane Biophysics
• Peptide Design

Background:

• Amphipathic peptides can disrupt cell membranes.
• Previous de novo designed peptides showed non-selective vesicle leakage.
• Crown ether-substituted peptides were previously non-selective.

Purpose of the Study:

• To engineer selective membrane-disrupting peptides.
• To investigate the effect of charge position on peptide selectivity.
• To differentiate between pore formation and micellization mechanisms.

Main Methods:

• De novo peptide design with substitutions.
• Synthesis of crown ether-substituted peptides.
• Vesicle leakage assays using calcein dye.
• Analysis of secondary structure (helical vs. β-sheet).

Main Results:

• Peptide selectivity against negatively charged dimyristoylphosphatidylglycerol (DMPG) bilayers was achieved.
• Some modified peptides showed selective leakage of DMPG vesicles but not dimyristoylphosphatidylcholine vesicles.
• Leakage was confirmed to be via pore formation.
• Selective peptides adopted a β-sheet structure, while non-selective ones were helical.

Conclusions:

• Peptide secondary structure (β-sheet vs. helical) dictates membrane selectivity.
• Strategic placement of charged residues enhances peptide selectivity for bacterial model membranes.
• β-sheet conformation is associated with higher bilayer selectivity.