Coarse-Grained Simulations of Membranes under Tension

TL;DR

This study uses Monte-Carlo simulations of a coarse-grained lipid bilayer model to explore how membrane properties and phases change under tension, revealing structural transitions and fluctuation behaviors.

Contribution

It provides a comprehensive analysis of membrane behavior under tension across different phases, including phase transitions and fluctuation characteristics, using coarse-grained simulations.

Findings

High tension induces structural changes in fluid membranes.

Ripple phase disappears under tension, replaced by interdigitated phase.

Tension influences membrane fluctuations and protein interactions.

Abstract

We investigate the properties of membranes under tension by Monte-Carlo simulations of a generic coarse-grained model for lipid bilayers. We give a comprising overview of the behavior of several membrane characteristics, such as the area per lipid, the monolayer overlap, the nematic order, and pressure profiles. Both the low-temperature regime, where the membranes are in a gel phase, and the high-temperature regime, where they are in the fluid phase, are considered. In the gel state, the membrane is hardly influenced by tension. In the fluid state, high tensions lead to structural changes in the membrane, which result in different compressibility regimes. The ripple state, which is found at tension zero in the transition regime between the fluid and the gel phase, disappears under tension and gives way to an interdigitated phase. We also study the membrane fluctuations in the fluid phase. In the low tension regime the data can be fitted nicely to a suitably extended elastic theory. At higher tensions the elastic fit consistently underestimates the strength of long-wavelength fluctuations. Finally, we investigate the influence of tension on the effective interaction between simple transmembrane inclusions and show that tension can be used to tune the hydrophobic mismatch interaction between membrane proteins.