Lipid bilayer membranes with asymmetrically distributed LPC and DAG

Abstract

The complex chemical and biophysical characteristics of biomembranes are influenced by the asymmetric distribution of specific lipids. In vitro, the introduction of lysophosphatidylcholine (LPC) into one leaflet of lipid bilayers is frequently utilized to regulate membrane protein activity. In vivo, the conversion of phosphatidylinositol 4,5-bisphosphate (PIP₂) to diacylglycerol (DAG) in one leaflet can also modulate membrane protein activities. However, the effects of such variations in lipid composition, lipid quantity, and particularly the asymmetry of lipid distribution on the properties and morphology of biomembranes remain to be fully elucidated. Through molecular dynamics simulations, we demonstrate that the asymmetric distribution of LPC and the asymmetric conversion of PIP₂ induce asymmetric alterations in membrane structures and lipid dynamics. Such alterations can generate an imbalance in the lateral pressure distribution between the two leaflets, potentially leading to membrane curvature. The extent of membrane curvature is also influenced by the length and degree of unsaturation of the lipid acyl tail chain. Our findings underscore the critical role of lipid asymmetry in shaping biomembrane structure and dynamics, providing new insights into the regulation of membrane proteins and cellular functions mediated by these specific lipids.