Interactions of the antimicrobial beta-peptide beta-17 with phospholipid vesicles differ from membrane interactions of magainins.

We have studied the interaction of beta-17, a potent synthetic antimicrobial beta-peptide, with phospholipids. We find that unlike other antimicrobial peptides such as magainin II, beta-17 facilitates the formation of nonbilayer phases, indicating that the peptide promotes negative curvature. Studies of liposomal leakage also indicate a different mode of membrane interaction relative to magainin II, but both leakage and membrane binding show that beta-17, like magainin II, has strong affinity for membranes containing anionic lipids. This is likely to be an important factor contributing to the antimicrobial specificity of the beta-peptide.