Biophysical Society Thematic Meeting | Hamburg 2022

Biophysics at the Dawn of Exascale Computers

Poster Abstracts

43-POS Board 43 LIPID BICELLES AS A TOOL TO UNLOCK MEMBRANE DYNAMICS Matthias Pöhnl 1 ; Rainer Böckmann 1,2 ; 1 Friedrich-Alexander-Universität Erlangen-Nürnberg, Biology, Erlangen, Germany 2 Erlangen National High Performance Computing Center (NHR@FAU), Erlangen, Germany Cholesterol is a major constituent of membranes in all animals and able to flip between leaflets on timescales orders of magnitude faster than other lipids. But both the distribution of cholesterol between the leaflets as well as the interplay between the distribution and other membrane properties is largely unknown. Difficulties in resolving the particular role of cholesterol for biomembrane characteristics are connected to the limited spatial and temporal resolution in experiments and challenges in studying asymmetric membranes and connected domain formation in simulations [1-2]. In a previous work we were able to show that lipid bicelle systems are a viable tool in simulations to investigate protein-induced membrane curvature [3]. Here, we developed a bicelle model that prevents diffusive lipid exchange between the leaflets, thus allowing for the study of defined asymmetric membrane compositions. While key membrane properties like area per lipid and membrane thickness are unmodified as compared to membranes constrained by periodic boundary conditions, bicelle systems allow for fluctuations with an increased amplitude. Interestingly, the addition of cholesterol substantially further increases these fluctuations accompanied by cholesterol flips between the membrane leaflets. This suggests a role of cholesterol in membrane remodeling processes, e.g in fusion. References [1] van Meer G., Cold Spring Harb. Perspect. Biol., 2011, 3(5) [2] Murate M. et al., Chem Phys Lipids, 2016, 194, 58-71 [3] Kluge C. et al, Biophys J., 2022

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