The antimicrobial peptide gramicidin S permeabilizes phospholipid bilayer membranes without forming discrete ion channels Academic Article uri icon

Overview

MeSH Major

  • Anti-Infective Agents
  • Gramicidin
  • Ion Channels
  • Lipid Bilayers
  • Phospholipids

abstract

  • We examined the permeabilization of lipid bilayers by the beta-sheet, cyclic antimicrobial decapeptide gramicidin S (GS) in phospholipid bilayers formed either by mixtures of zwitterionic diphytanoylphosphatidylcholine and anionic diphytanoylphosphatidylglycerol or by single zwitterionic unsaturated phosphatidylcholines having various hydrocarbon chain lengths, with and without cholesterol. In the zwitterionic bilayers formed by the phosphatidylcholines, without or with cholesterol, the peptide concentrations and membrane potentials required to initiate membrane permeabilization vary little as function of bilayer thickness and cholesterol content. In all the systems tested, the GS-induced transient ion conductance events exhibit a broad range of conductances, which are little affected by the bilayer composition or thickness. In the zwitterionic phosphatidylcholine bilayers, the effect of GS does not depend on the polarity of the transmembrane potential; however, in bilayers formed from mixtures of phosphatidylcholines and anionic phospholipids, the polarity of the transmembrane potential becomes important, with the GS-induced conductance events being much more frequent when the GS-containing solution is positive relative to the GS-free solution. Overall, these results suggest that GS does not form discrete, well-defined, channel-like structures in phospholipid bilayers, but rather induces a wide variety of transient, differently sized defects which serve to compromise the bilayer barrier properties for small electrolytes.

publication date

  • December 2008

Research

keywords

  • Academic Article

Identity

Language

  • eng

PubMed Central ID

  • PMC2614689

Digital Object Identifier (DOI)

  • 10.1016/j.bbamem.2008.08.017

PubMed ID

  • 18809374

Additional Document Info

start page

  • 2814

end page

  • 22

volume

  • 1778

number

  • 12