Antimicrobial peptide magainin I from Xenopus skin forms anion-permeable channels in planar lipid bilayers.
The ionophore properties of magainin I, an antimicrobial and amphipathic peptide from the skin of Xenopus, were investigated in planar lipid bilayers. Circular dichroism studies, performed comparatively with alamethicin, in small or large unilamellar phospholipidic vesicles, point to a smaller proportion of alpha-helical conformation in membranes. A weakly voltage-dependent macroscopic conductance which is anion-selective is developed when using large aqueous peptide concentration with lipid bilayer under high voltages. Single-channel experiments revealed two main conductance levels occurring independently in separate trials. Pre-aggregates lying on the membrane surface at rest and drawn into the bilayer upon voltage application are assumed to account for this behaviour contrasting with the classical multistates displayed by alamethicin.
Duclohier
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H
UA 500 CNRS, Faculté des Sciences de Rouen, Mont Saint-Aignan, France.
Molle
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G
Spach
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G
D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D002942:Circular Dichroism; D004553:Electric Conductivity; D007473:Ion Channels / Q000502:physiology*; D008051:Lipid Bilayers; D008954:Models, Biological; D008969:Molecular Sequence Data; D010455:Peptides; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D011487:Protein Conformation; D012867:Skin; D029867:Xenopus Proteins; D014982:Xenopus laevis
D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D007473:Ion Channels; D008051:Lipid Bilayers; D010455:Peptides; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D029867:Xenopus Proteins; C053300:magainin 1 peptide, Xenopus; C020888:1,2-dielaidoylphosphatidylethanolamine; C028694:1-palmitoyl-2-oleoylphosphatidylcholine