Strong Membrane Permeabilization Activity Can Reduce Selectivity of Cyclic Antimicrobial Peptides

Area of Science:

• Membrane biophysics
• Antimicrobial peptide research
• Drug discovery

Background:

• Selectivity is essential for membrane-active antimicrobials.
• Mechanistic understanding of peptide selectivity guides rational design.
• Previous studies show these peptides target bacterial membranes without direct permeabilization.

Purpose of the Study:

• Compare selectivity mechanisms of two similar cyclic peptides.
• Elucidate peptide-membrane interactions using biophysical methods.
• Investigate how residue arrangement affects antimicrobial selectivity.

Main Methods:

• Systematic study of peptide interactions with model membranes (PC, PG/PE).
• Utilized various biophysical techniques.
• Compared effects on vesicle leakage, lipid packing, aggregation, and fusion.

Main Results:

• Both peptides bind more efficiently to negatively charged membranes.
• Peptides induce vesicle leakage, lipid packing changes, aggregation, and fusion in PG/PE membranes.
• Peptide with adjacent hydrophobic residues shows more pronounced effects, leading to reduced selectivity.

Conclusions:

• Clustered hydrophobic residues enhance membrane interaction but reduce selectivity.
• Unselective leakage is linked to deeper lipid layer insertion.
• Strategies avoiding hydrophobic residue accumulation may improve antimicrobial selectivity.