Transmembrane peptide-induced lipid sorting and mechanism of Lalpha-to-inverted phase transition using coarse-grain molecular dynamics.

Nielsen SO, Lopez CF, Ivanov I, Moore PB, Shelley JC, Klein ML
Biophys J. 2004 87 (4): 2107-15

PMID: 15454415 · PMCID: PMC1304638 · DOI:10.1529/biophysj.104.040311

Molecular dynamics results are presented for a coarse-grain model of 1,2-di-n-alkanoyl-sn-glycero-3-phosphocholine, water, and a capped cylindrical model of a transmembrane peptide. We first demonstrate that different alkanoyl-length lipids are miscible in the liquid-disordered lamellar (Lalpha) phase. The transmembrane peptide is constructed of hydrophobic sites with hydrophilic caps. The hydrophobic length of the peptide is smaller than the hydrophobic thickness of a bilayer consisting of an equal mixture of long and short alkanoyl tail lipids. When incorporated into the membrane, a meniscus forms in the vicinity of the peptide and the surrounding area is enriched in the short lipid. The meniscus region draws water into it. In the regions that are depleted of water, the bilayers can fuse. The lipid headgroups then rearrange to solvate the newly formed water pores, resulting in an inverted phase. This mechanism appears to be a viable pathway for the experimentally observed Lalpha-to-inverse hexagonal (HII) peptide-induced phase transition.

Copyright 2004 Biophysical Society

MeSH Terms (14)

Computer Simulation Dimyristoylphosphatidylcholine Hydrophobic and Hydrophilic Interactions Lipid Bilayers Membrane Fluidity Membrane Microdomains Membrane Proteins Models, Chemical Models, Molecular Peptides Phase Transition Porosity Protein Conformation Water

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