Spectroscopic, zeta potential and molecular dynamics studies of the interaction of antimicrobial peptides with model bacterial membrane.

Abstract

Peptide-membrane interactions play a key role in the mechanisms of activity of antimicrobial peptides. Here, methods of fluorescence spectroscopy, zeta potential, and molecular dynamics modeling were used to study the interaction of new antimicrobial peptide megin with model bacterial membrane. The Gibbs free energy of -6kcal/mol characterizes the interaction of the peptides with liposomes containing DOPE and POPG lipids. Fluorescence data, acrylamide quenching, and MD simulations show that megin peptides are mainly located at the lipid/water interface and are aligned parallel to the bilayer surface in a carpet like manner. Measurements of zeta potential demonstrate the decrease of the negative potential of liposomes in the presence of peptides. The influence of megin on the membrane properties is also confirmed by molecular dynamics simulations. Insertion of peptides into the membrane disturbs lipid ordering, decreases the order parameters of lipids, and facilitates penetration of water molecules through the membrane. According to our results, we proposed that the megin antimicrobial activity can be explained by the carpet model of peptide activity.