Interaction of lytic peptides and model membranes: intefacial action and induction of lipid domains

Abstract

Studies of the correlations between structural features of lytic peptides, from the mastoparan family, and their lytic activity in model membrane and antimicrobial activity developed in our laboratory by different experimental approaches, have evidenced different mechanisms of action for the same peptide, depending on the peptide to lipid ratio. These studies have revealed that a group of mastoparan peptides extracted from the venom of native wasps have interfacial activity. They also revealed that in the bilayer-solvent interface there is a complex balance between electrostatic and hydrophobic interactions which associated with elastic properties of the bilayer modulate the lytic activity and their selectivities to membranes. These studies provided evidences that some of these peptides induced lipid domain formation or lipid segregation in vesicles which could be an alternative mechanism of action for the interfacial activity. The purpose of the present project is to deepen the investigations on the interfacial activity and on the lipid domain formation by using experiments of lipid monolayers at air-water interface. Lipid monolayers are used as model for the solvent - bilayer outer leaflet interface. These experiments can provide important informations for the interfacial activity, such as, peptide penetration in the monolayer , changes in peptide and lipid molecular areas, partition coefficients for the peptide adsorption, changes induced by the peptides on the area compression modulus of the monolayer and the peptide impact on the pressure - area lipid isotherms, These informations will be used in association with those obtained from the other techniques that have been used in these studies. These data will be important to advance on the comprehension of the mechanisms involved on the interfacial action and on the physicochemical bases of the synergy observed on the solvent - bilayer interface. (AU)