tailieunhanh - Báo cáo khoa học: Interactions of the antimicrobial b-peptide b-17 with phospholipid vesicles differ from membrane interactions of magainins

We have studied the interaction ofb-17, a potent synthetic antimicrobialb-peptide, with phospholipids. We find that unlikeother antimicrobial peptides suchasmagainin II,b-17 facilitates the formation of nonbilayer phases, indicating that the peptide promotes negative curvature. Studies of liposomal leakage also indicate a different mode of mem-brane interaction relative to magainin II, but both leakage andmembrane binding showthatb-17, likemagainin II, has strongaffinity formembranes containinganionic lipids | Eur. J. Biochem. 270 1240-1248 2003 FEBS 2003 doi Interactions of the antimicrobial p-peptide p-17 with phospholipid vesicles differ from membrane interactions of magainins Raquel F. Epand1 Naoki Umezawa2 Emilie A. Porter2 Samuel H. Gellman2 and Richard M. Epand1 1 Department of Biochemistry McMaster University Health Sciences Centre Hamilton Canada department of Chemistry University of Wisconsin Wisconsin USA We have studied the interaction of b-17 a potent synthetic antimicrobial b-peptide with phospholipids. We find that unlike other antimicrobial peptides such as magainin II b-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 b-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 b-peptide. Keywords b-peptide antimicrobial peptide-lipid interactions membrane leakage membrane intrinsic curvature. There is currently extensive interest in developing new antimicrobial agents to counter the growing clinical problem of bacterial resistance to traditional antibiotics - . A large variety of natural peptides and synthetic derivatives display antimicrobial activity 2 and these peptides have been viewed as potential sources of new therapeutic agents. Nearly all of the synthetic derivatives have been constructed from a-amino acids as are the natural host-defense peptides. Recently antimicrobial activity has been reported for a number of b-amino acid oligomers b-peptides 3-8 . b-Peptides differ from conventional peptides a-amino acid residues in two important ways. First the unnatural backbone of b-peptides confers resistance to degradation by proteolytic enzymes 8-10 . Second b-peptides constructed from .