Why and how are peptide-lipid interactions utilized for self defence?

Animals defend themselves against invading pathogenic micro-organisms by utilizing cationic anti-microbial peptides, which rapidly kill various micro-organisms without exerting toxicity against the host. Physicochemical peptide-lipid interactions provide attractive mechanisms for innate immunity. Many of these peptides form amphipathic secondary structures (alpha-helices and beta-sheets) which can selectively interact with anionic bacterial membranes by electrostatic interaction. Rapid, peptide-induced membrane permeabilization is an effective mechanism of anti-microbial action. Magainin 2 from frog skin forms a dynamic peptide-lipid supramolecular-complex pore that allows mutually coupled transmembrane transport of ions and lipids. The peptide molecule is internalized upon the disintegration of the pore. Several anti-microbial peptides are known to work synergistically.