Spontaneous Buckling of Lipid Bilayer and Vesicle Budding Induced by Antimicrobial Peptide Magainin 2: A Coarse-Grained Simulation Study

J Phys Chem B. 2011 Jun 30;115(25):8122-9. doi: 10.1021/jp2023023. Epub 2011 Jun 9.

Abstract

Molecular mechanisms of the action of antimicrobial peptides on bacterial membranes were studied by large scale coarse-grained simulations of magainin 2-dipalmitoylphosphatidylcholine/palmitoyloleoylphosphatidylglycerol (DPPC/POPG) mixed bilayer systems with spatial extents up to 0.1 μm containing up to 1600 peptides. Equilibrium simulations exhibit disordered toroidal pores stabilized by peptides. However, when a layer of peptides is placed near the lipid head groups on one side of the bilayer only, their incorporation leads to a spontaneous buckling of the bilayer. This buckling is followed by the formation of a quasi-spherical vesicular bud connected to the bilayer by a narrow neck. The mean curvature of the budding region is consistent with what is expected based on the dependence of the area per lipid on the peptide-to-lipid ratio in equilibrium simulations. Our simulations suggest that the incorporation of antimicrobial peptides on the exterior surface of a vesicle or a bacterial cell leads to buckling and vesicle budding, presumably accompanied by nucleations of giant transient pores of sizes that are much larger than indicated by equilibrium measurements and simulations.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • 1,2-Dipalmitoylphosphatidylcholine / chemistry
  • Lipid Bilayers / chemistry*
  • Magainins / chemistry*
  • Molecular Dynamics Simulation
  • Phosphatidylglycerols / chemistry
  • Xenopus Proteins / chemistry*

Substances

  • Lipid Bilayers
  • Magainins
  • Phosphatidylglycerols
  • Xenopus Proteins
  • magainin 2 peptide, Xenopus
  • 1,2-Dipalmitoylphosphatidylcholine
  • 1-palmitoyl-2-oleoylglycero-3-phosphoglycerol