Curvature Driven Membrane Organisation Revealed by Single Molecule Imaging in Droplet Interface Bilayers

Abstract

Membrane curvature plays a crucial role in lipid and protein sorting within the cell membrane [1] giving rise to spontaneous self-organisation and localisation of complex biological macromolecules. Such spatial organisation in response to, and in generating, membrane curvature contributes to many important biological processes such as neurotransmission, trafficking and cell division [2]. Despite this importance, the majority of in-vitro studies are performed in planar or pseudo-planar (GUV) bilayer systems. As such, there is a need for novel strategies to more closely mimic the curvature of cellular membranes, whilst allowing for correlated measurements of protein function.Here, we create Droplet Interface Bilayers (DIBs) [3] on an underlying curved substrate, resulting in the morphology of the underlying substrate being reflected in the curvature of the bilayer. Total Internal Reflection Fluorescence (TIRF) imaging reveals the correlation of lipid domain formation at sites of intrinsic curvature and the preferential localisation and pore formation by antimicrobial peptides at regions of positive curvature. This technique provides a new method for dictating the curvature of artificial bilayers, enabling single molecule studies on the role of curvature in membrane organisation and function.1. Ramamurthi, K. S. et al. Science 2009 323, 1354.2. McMahon, H. T. et al. Nature 2005 438, 590.3. Thompson, J. R. et al. Nano Letters 2007 7, 3875.