Membrane-Protein Interactions in a Generic Coarse-Grained Model for Lipid Bilayers

TL;DR

This study uses Monte Carlo simulations of a coarse-grained lipid bilayer model to analyze membrane-protein interactions, comparing results with analytical theories and identifying key factors influencing lipid-mediated forces.

Contribution

It provides a systematic comparison of simulation results with Landau-de Gennes and elastic theories, highlighting their strengths and limitations in describing membrane-protein interactions.

Findings

Elastic theory accurately predicts membrane fluctuations and deformation profiles.

Simulation data shows discrepancies with elastic theory for large protein separations.

Lipid-mediated interactions are governed by five competing factors.

Abstract

We study membrane-protein interactions and membrane-mediated protein-protein interactions by Monte Carlo simulations of a generic coarse-grained model for lipid bilayers with cylindrical hydrophobic inclusions. The strength of the hydrophobic force and the hydrophobic thickness of the proteins are systematically varied. The results are compared with analytical predictions of two popular analytical theories: The Landau-de Gennes theory and the elastic theory. The elastic theory provides an excellent description of the fluctuation spectra of pure membranes and successfully reproduces the deformation profiles of membranes around single proteins. However, its prediction for the potential of mean force between proteins is not compatible with the simulation data for large distances. The simulations show that the lipid-mediated interactions are governed by five competing factors: Direct interactions, lipid-induced depletion interactions, lipid bridging, lipid packing, and a smooth long-range contribution. The mechanisms leading to "hydrophobic mismatch" interactions are critically analyzed.