Modulation of glycophorin A transmembrane helix interactions by lipid bilayers: Molecular dynamics calculations

Horia I. Petrache, Alan Grossfield, Kevin R. MacKenzie, Donald M. Engelman, Thomas B. Woolf

Research output: Contribution to journalArticlepeer-review

Abstract

Starting from the glycophorin A dimer structure determined by NMR, we performed simulations of both dimer and monomer forms in explicit lipid bilayers with constant normal pressure, lateral area, and temperature using the CHARMM potential. Analysis of the trajectories in four different lipids reveals how lipid chain length and saturation modulate the structural and energetic properties of transmembrane helices. Helix tilt, helix-helix crossing angle, and helix accessible volume depend on lipid type in a manner consistent with hydrophobic matching concepts: the most relevant lipid property appears to be the bilayer thickness. Although the net helix-helix interaction enthalpy is strongly attractive, analysis of residue-residue interactions reveals significant unfavorable electrostatic repulsion between interfacial glycine residues previously shown to be critical for dimerization. Peptide volume is nearly conserved upon dimerization in all lipid types, indicating that the monomeric helices pack equally well with lipid as dimer helices do with one another. Enthalpy calculations indicate that the helix-environment interaction energy is lower in the dimer than in the monomer form, when solvated by unsaturated lipids. In all lipid environments there is a marked preference for lipids to interact with peptide predominantly through one rather than both acyl chains. Although our trajectories are not long enough to allow a full thermodynamic treatment, these results demonstrate that molecular dynamics simulations are a powerful method for investigating the protein-protein, protein-lipid, and lipid-lipid interactions that determine the structure, stability and dynamics of transmembrane α-helices in membranes. (C) 2000-Academic Press.

Original languageEnglish (US)
Pages (from-to)727-746
Number of pages20
JournalJournal of molecular biology
Volume302
Issue number3
DOIs
StatePublished - Sep 22 2000

Keywords

  • Dimerization motif
  • Glycophorin A transmembrane domain
  • Membrane proteins
  • Protein-lipid interactions
  • α-helix association

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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