Magainins as paradigm for the mode of action of pore forming polypeptides

Magainins are a class of antimicrobial peptides discovered in the skin of Xenopus laevis. The peptides kill bacteria by permeabilizing the cell membranes without exhibiting significant toxicity against mammalian cells, and are a promising candidate for a new antibiotic of therapeutic value. The main target of the peptides are considered to be the lipid matrix of the membranes. This review summarizes studies on magainin-lipid interactions in comparison with other pore forming peptides. The selective toxicity can be at least partly explained by preferential interactions of magainins with anionic phospholipids abundant in bacterial membranes. A novel mode of action is discussed in detail, i.e., the formation of a dynamic peptide-lipid supramolecular pore, which allows the mutually coupled transbilayer transport of ions, lipids, and peptides per se.