Lipid-Lipid Coupling to Membrane Curvature by Simulation and NMR

Abstract

The material properties of a bilayer must be determined by the chemical structure of its lipid components and the interactions between them. The preferred (“spontaneous”) curvature of a lipid leaflet is one of the most interesting properties as it is the most direct connection between the stability of leaflet structures and lipid chemistry. For example, the curved lipid hexagonal phase is stabilized by phosphatidylethanolamine head groups.Nuclear magnetic resonance spectroscopy and molecular dynamics can probe structure on the molecular level, but relating these techniques to material properties requires new models and theoretical methods.In this work, we use computer simulation of lipid bilayers (in particular, sphingomyelin and DPPC) to predict the impact of chemical structure on spontaneous curvature. Then, NMR applied to small vesicles measures how lipid identity controls population of the inner and outer leaflet, reflecting the lipid's spontaneous curvature. Simulations predict that at low concentration of sphingomyelin, strong coupling between lipids determines this behavior in a non-linear way, in contrast to DPPC.