Coarse-grained molecular dynamics simulations of membrane proteins and peptides

J Struct Biol. 2007 Mar;157(3):593-605. doi: 10.1016/j.jsb.2006.10.004. Epub 2006 Oct 20.

Abstract

Molecular dynamics (MD) simulations provide a valuable approach to the dynamics, structure, and stability of membrane-protein systems. Coarse-grained (CG) models, in which small groups of atoms are treated as single particles, enable extended (>100 ns) timescales to be addressed. In this study, we explore how CG-MD methods that have been developed for detergents and lipids may be extended to membrane proteins. In particular, CG-MD simulations of a number of membrane peptides and proteins are used to characterize their interactions with lipid bilayers. CG-MD is used to simulate the insertion of synthetic model membrane peptides (WALPs and LS3) into a lipid (PC) bilayer. WALP peptides insert in a transmembrane orientation, whilst the LS3 peptide adopts an interfacial location, both in agreement with experimental biophysical data. This approach is extended to a transmembrane fragment of the Vpu protein from HIV-1, and to the coat protein from fd phage. Again, simulated protein/membrane interactions are in good agreement with solid state NMR data for these proteins. CG-MD has also been applied to an M3-M4 fragment from the CFTR protein. Simulations of CFTR M3-M4 in a detergent micelle reveal formation of an alpha-helical hairpin, consistent with a variety of biophysical data. In an I231D mutant, the M3-M4 hairpin is additionally stabilized via an inter-helix Q207/D231 interaction. Finally, CG-MD simulations are extended to a more complex membrane protein, the bacterial sugar transporter LacY. Comparison of a 200 ns CG-MD simulation of LacY in a DPPC bilayer with a 50 ns atomistic simulation of the same protein in a DMPC bilayer shows that the two methods yield comparable predictions of lipid-protein interactions. Taken together, these results demonstrate the utility of CG-MD simulations for studies of membrane/protein interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cell Membrane / chemistry
  • Computer Simulation*
  • Cystic Fibrosis Transmembrane Conductance Regulator / chemistry
  • Human Immunodeficiency Virus Proteins
  • Humans
  • Membrane Proteins / chemistry*
  • Membrane Transport Proteins / chemistry
  • Molecular Sequence Data
  • Peptides / chemistry*
  • Viral Regulatory and Accessory Proteins / chemistry

Substances

  • Human Immunodeficiency Virus Proteins
  • Membrane Proteins
  • Membrane Transport Proteins
  • Peptides
  • Viral Regulatory and Accessory Proteins
  • vpu protein, Human immunodeficiency virus 1
  • Cystic Fibrosis Transmembrane Conductance Regulator
  • lactose permease