Antibacterial peptide pleurocidin forms ion channels in planar lipid bilayers

• Published in: Biochimica et biophysica acta Vol. 1564; no. 2; pp. 359 - 364
• Main Authors: Saint, Nathalie, Cadiou, Hervé, Bessin, Yannick, Molle, Gérard
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 31.08.2002
• Subjects: Amino Acid Sequence; Amphipathy; Antimicrobial Cationic Peptides - pharmacology; Fish; Fish Proteins; Hydrogen-Ion Concentration; Ion Channels - chemistry; Lipid Bilayers - chemistry; Molecular Sequence Data; Patch-Clamp Techniques; Permeability; Pore-forming; Proteins - pharmacology; Skin mucus; Temperature; α Helix; Fish; Skin mucus; Amphipathy; Pore-forming; α Helix
• ISSN: 0005-2736; 0006-3002; 1879-2642
• DOI: 10.1016/S0005-2736(02)00470-4

Pleurocidin, a 25-residue α helical cationic peptide, isolated from skin mucous secretions of the winter flounder, displays a strong anti-microbial activity and appears to play a role in innate host defence. This peptide would be responsible for pore formation in the membrane of bacteria leading to lysis and therefore death. In this study, we investigated the behaviour of pleurocidin in different planar lipid bilayers to determine its mechanism of membrane permeabilisation. Macroscopic conductance experiments showed that pleurocidin did not display a pore-forming activity in neutral phosphatidylcholine/phosphatidylethanolamine (PC/PE) lipid bilayers. However, in 7:3:1 PC/PE/phosphatidylserine (PS) lipid bilayers, pleurocidin showed reproducible I/ V curves at different peptide concentrations. This activity is confirmed by single-channel experiments since well-defined ion channels were obtained if the lipid mixture was containing an anionic lipid (PS). The ion channel characteristics such as—no voltage dependence, only one unitary conductance, linear relation ship current–voltage—, are not in favour of the membrane permeabilisation according to the barrel model but rather by the toroidal pore formation.