Aggregation of Model Membrane Proteins, Modulated by Hydrophobic Mismatch, Membrane Curvature, and Protein Class

Biophys J. 2011 Aug 3;101(3):691-9. doi: 10.1016/j.bpj.2011.06.048.

Abstract

Aggregation of transmembrane proteins is important for many biological processes, such as protein sorting and cell signaling, and also for in vitro processes such as two-dimensional crystallization. We have used large-scale simulations to study the lateral organization and dynamics of lipid bilayers containing multiple inserted proteins. Using coarse-grained molecular dynamics simulations, we have studied model membranes comprising ∼7000 lipids and 16 identical copies of model cylindrical proteins of either α-helical or β-barrel types. Through variation of the lipid tail length and hence the degree of hydrophobic mismatch, our simulations display levels of protein aggregation ranging from negligible to extensive. The nature and extent of aggregation are shown to be influenced by membrane curvature and the shape or orientation of the protein. Interestingly, a model β-barrel protein aggregates to form one-dimensional strings within the bilayer plane, whereas a model α-helical bundle forms two-dimensional clusters. Overall, it is clear that the nature and extent of membrane protein aggregation is dependent on several aspects of the proteins and lipids, including hydrophobic mismatch, protein class and shape, and membrane curvature.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cell Membrane / chemistry
  • Cell Membrane / metabolism*
  • Diffusion
  • Hydrophobic and Hydrophilic Interactions*
  • Lipid Bilayers / chemistry
  • Lipid Bilayers / metabolism
  • Membrane Proteins / chemistry*
  • Membrane Proteins / metabolism*
  • Molecular Dynamics Simulation*
  • Molecular Sequence Data
  • Porosity
  • Protein Multimerization*
  • Protein Structure, Secondary
  • Unilamellar Liposomes / chemistry
  • Unilamellar Liposomes / metabolism

Substances

  • Lipid Bilayers
  • Membrane Proteins
  • Unilamellar Liposomes