Hindawi Publishing Corporation Journal of Biophysics Volume 2010, Article ID 179641, 12 pages doi:10.1155/2010/179641 Research Article Exploring the Membrane Mechanism of the Bioactive Peptaibol Ampullosporin A Using Lipid Monolayers and Supported Biomimetic Membranes Marguerita Eid, 1 Sonia Rippa, 1 Sabine Castano, 2 Bernard Desbat, 2 Jo¨ el Chopineau, 3, 4 Claire Rossi, 1 and Laure B´ even 1, 5, 6 1 UMR 6022 CNRS G´ enie Enzymatique et Cellulaire, Universit´ e de Technologie de Compi` egne, BP 20529, 60205 Compi` egne Cedex, France 2 CBMN, Chimie et Biologie des Membranes et des Nanoobjets CNRS, UMR 5248, Universit´ e de Bordeaux I, ENITAB, 33607 Pessac, France 3 CNRS, UMR 5253 Institut Charles Gerhardt, Universit´ e Montpellier 2, Ecole Nationale Sup´ erieure de Chimie de Montpellier, Universit´ e Montpellier 1, 34093 Montpellier Cedex, France 4 Universit´ e de Nˆ ımes, 30000 Nˆ ımes, France 5 INRA, UMR 1090 G´ enomique Diversit´ e et Pouvoir Pathog` ene, 33883 Villenave d’Ornon, France 6 Universit´ e de Bordeaux 2, UMR 1090 G´ enomique Diversit´ e Pouvoir Pathog` ene, 33883 Villenave d’Ornon Cedex, France Correspondence should be addressed to Claire Rossi, claire.rossi@utc.fr and Laure B´ even, laure.beven@bordeaux.inra.fr Received 27 October 2010; Revised 9 December 2010; Accepted 20 December 2010 Academic Editor: Miguel Castanho Copyright © 2010 Marguerita Eid et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Ampullosporin A is an antimicrobial, neuroleptic peptaibol, the behavior of which was investigated in different membrane mimetic environments made of egg yolk L-α-phosphatidylcholine. In monolayers, the peptaibol adopted a mixed α/3 10 -helical structure with an in-plane orientation. The binding step was followed by the peptide insertion into the lipid monolayer core. The relevance of the inner lipid leaflet nature was studied by comparing ampullosporin binding on a hybrid bilayer, in which this leaflet was a rigid alkane layer, and on supported fluid lipid bilayers. The membrane binding was examined by surface plasmon resonance spectroscopy and the effect on lipid dynamics was explored using fluorescence recovery after photobleaching. In the absence of voltage and at low concentration, ampullosporin A substantially adsorbed onto lipid surfaces and its interaction with biomimetic models was strongly modified depending on the inner leaflet structure. At high concentration, ampullosporin A addition led to the lipid bilayers disruption. 1. Introduction Living cells naturally produce diverse membranotropic pep- tides displaying antifungal and/or antibacterial activities. These properties have been attributed to their molecular interaction with the target cell membranes. Three basic models have been proposed for membrane interaction mech- anisms leading to membrane permeabilization. The first model consists in the formation of barrel-stave pores [1], in which the pore lumen is formed by the polar side of amphi- pathic and helical peptide monomers assembled into a bun- dle. The second major mechanism that has been proposed for membranolytic, amphipathic peptides is the formation of the so-called “toroidal” transient pores [2, 3]. In this model, the peptides bind to the polar head groups of the cell membrane phospholipids (PL) and, above a critical peptide concentra- tion, continuously bend the lipid leaflet favouring the forma- tion of a pore lined by both the peptides and the lipid polar headgroups. The third major model is called the “carpet-like” mechanism. While the two former modes of action require the formation of a pore structure, the latter one is subsequent to the accumulation of flat-oriented peptides at the lipid bilayer surface and may lead to membrane disruption and formation of mixed lipid-peptide aggregates [4].