Anomalous diffusion of phospholipids and cholesterols in a lipid bilayer and its origins

TL;DR

This study uses molecular dynamics simulations and trajectory analysis to reveal that lipids in bilayers exhibit subdiffusive behavior influenced by composition, with fractional Langevin equation motion describing their dynamics across phases.

Contribution

It systematically demonstrates that lipid motion in bilayers follows fractional Langevin equation dynamics, highlighting the impact of chemical composition and cholesterol on diffusion behavior.

Findings

Lipid motion exhibits subdiffusion over four orders of magnitude in time.

Cholesterol presence affects the diffusion dynamics of lipids.

Fractional Langevin equation universally describes lipid motion in various phases.

Abstract

Combining extensive molecular dynamics simulations of lipid bilayer systems of varying chemical composition with single-trajectory analyses we systematically elucidate the stochastic nature of the lipid motion. We observe subdiffusion over more than four orders of magnitude in time, clearly stretching into the sub-microsecond domain. The lipid motion delicately depends on the lipid chemistry, the lipid phase, and especially on the presence of cholesterol. We demonstrate that fractional Langevin equation motion universally describes the lipid motion in all phases including the gel phase, and in the presence of cholesterol. The results underline the relevance of anomalous diffusion in lipid bilayers and the strong effects of the membrane composition.