Bending fluctuation is one of the most important dynamic modes of lipid membranes. These fluctuations play a vital role in many biological processes, most notoriously, contributing to the regulation of membrane protein activity. We investigated the bilayer structural properties and the bending rigidity of liposomes with an asymmetric transbilayer distribution of high- and low-melting lipids (asymmetric large unilamellar vesicles, aLUVs). The aLUVs were generated using cyclodextrin-catalyzed lipid exchange. The resulting aLUVs were composed of an egg sphingomyelin (ESM) enriched outer leaflet and a 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) inner leaflet. A combination of small angle X-ray scattering (SAXS) and small angle neutron scattering (SANS) were used to determine the bilayer structure at different temperatures. Using neuctron spin-echo (NSE) spectroscopy, the aLUVs were measured at three temperature conditions; i) where ESM and POPE are both gel, ii) ESM is gel and POPE is fluid and iii) both ESM and POPE are fluid. Under these conditions we find that the asymmetric organization of lipid increases the overall strength of the bending fluctuations, thus giving direct physical evidence of lipid-driven interleaflet coupling.

Transverse lipid organization dictates bending fluctuations in model plasma membranes

2019 Spring National Meeting

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