An Antimicrobial Peptide, Magainin 2, Induced Rapid Flip-Flop of Phospholipids Coupled with Pore Formation and Peptide Translocation

• Published in: Biochemistry (Easton) Vol. 35; no. 35; pp. 11361 - 11368
• Main Authors: Matsuzaki, Katsumi, Murase, Osamu, Fujii, Nobutaka, Miyajima, Koichiro
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 03.09.1996
• Subjects: Amino Acid Sequence; Animals; Anti-Infective Agents - pharmacology; Antimicrobial Cationic Peptides; Diffusion; Dithionite - metabolism; Fluoresceins - metabolism; Fluorescent Dyes - metabolism; Kinetics; Lipid Bilayers - metabolism; Liposomes - metabolism; Magainins; Mathematics; Molecular Sequence Data; Mutation; Peptides - genetics; Peptides - metabolism; Peptides - pharmacology; Permeability - drug effects; Phosphatidylethanolamines - metabolism; Phospholipids - metabolism; Skin - chemistry; Xenopus laevis; Xenopus Proteins
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi960016v

The effect of an antimicrobial peptide, magainin 2, on the flip-flop rates of phospholipids was investigated by use of fluorescent lipids, i.e., anionic N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)dipalmitoyl-l-α-phosphatidylethanolamine (NBD-PE), 1-oleoyl-2-[12-((7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)dodecanoyl]-l-α-phosphatidic acid (C12-NBD-PA), 1-oleoyl-2-[12-((7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)dodecanoyl]-l-α-phosphatidyl-l-serine (C12-NBD-PS), and zwitterionic 1-palmitoyl-2-[6-((7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)caproyl]-l-α-phosphatidylcholine (C6-NBD-PC). Their intrinsic flip-flop half-lives at 30 °C in the absence of the peptide were 1.1 h, ca. 7 h, ca. 8 days, and >2 days, respectively. The peptide accelerated the flip-flop half-lives of the fluorescent lipids to an order of minutes. Furthermore, the flip-flop was coupled with the membrane permeabilization and the peptide translocation [Matsuzaki, K., Murase, O., Fujii, N., & Miyajima, K. (1995) Biochemistry 34, 6521−6526], suggesting pore-mediated flip-flop. The flip-flop rate was independent of the initial labeling conditions (outer leaflet label or inner leaflet label). From these results, a model was proposed, in which the lipids translocate across the membrane by lateral diffusion along the wall of the pores composed of the peptides and the lipids. A simple theoretical calculation could explain the coupling of the flip-flop with the permeabilization.