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

Abstract

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-alpha- phosphatidylethanolamine (NBD-PE), 1-oleoyl-2-[12-((7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)- dodecanoyl]-L-alpha-phosphatidic acid (C12-NBD-PA), 1-oleoyl-2-[12- ((7-nitrobenz-2-oxa-1,3-diazol-4-yl)- amino)dodecanoyl]-L-alpha-phosphatidyl-L-serine (C12-NBD-PS), and zwitterionic 1-palmitoyl-2-[6-((7- nitrobenz-2-oxa-1,3-diazol-4-yl)amino)caproyl]-L-alpha-phosphatidy lcholine (C6-NBD-PC). Their intrinsic flip-flop half-lives at 30 degrees 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.

Optimization of transdermal delivery using magainin pore-forming peptide

“…Skin permeability to fluorescein was significantly increased (Student's t-test, p<0.01), but permeability to the two larger molecules was not significantly affected by magainin (Student's t-test, p>0.05). This can be explained because magainin is believed to form Angstrom-scale pores across lipid bilayers that are known to be large enough for transport only of small molecules [9,10].…”

Translocation of Analogues of the Antimicrobial Peptides Magainin and Buforin across Human Cell Membranes

“…After membrane binding, several magainin helices form a toroidal pore (diameter 2-3 nm) with surrounding lipid molecules in artificial membranes (35). Upon pore disintegration, a fraction of the peptide molecules translocates across the membrane (24).…”

Characterization of Streptococcus agalactiae CAMP Factor as a Pore-forming Toxin

“…This finding is not unprecedented with pore-forming peptides and proteins; e.g. even though evidence of oligomerization on membranes has been obtained with several pore-forming peptides such as melittin (28) or magainin (29) and with Bacillus thuringiensis ␦-endotoxin (30), stable oligomers of these molecules have not been recovered from the membranes. (With ␦-endotoxin, aggregates do form pores on brush border membrane vesicles; from these, only trimers were extracted, whereas the stoichiometry of the oligomer was expected to be larger than 3 (31)).…”