Lateral Diffusion Along Curved Lipid Bilayers

Abstract

Biomembranes are thin, encapsulating, lipid-based double-layered films prevalently crowded by membrane proteins, and the interactions between the lipids and the embedded proteins are an active field of study with vital relevance for cell biology and biomedicine. Many of these studies approximate lipid bilayers as flat planar structures, even though highly curved membranes, such as membrane tethers and buds, vesicles and liposomes, and in structures like cristae in mitochondria are prevailing. So far, it has been sufficient for scientists to answer simpler questions regarding biomembranes by focusing mainly on planar lipid bilayers. However, the advancements in experimental and computational methods allow and call for a deeper understanding also on how membrane curvature can affect the properties of membranes. This thesis sheds light on the diffusion of proteins and lipids in curved lipid membranes. By presenting the first molecular dynamics simulations on the diffusion of transmembrane proteins in membrane tubes, the dynamics of the lateral diffusion in curved environments are studied in detail. The presented results highlight the importance of nanoscale curvature and compare the effect to macromolecular crowding, another currently confirmed factor related to lateral diffusion in lipid membranes. After a careful comparison between the results of this thesis and both experimental and computational work performed previously, pointers are given on how membrane curvature facilitated effects on lateral diffusion can be studied in the future.