Biophysical Society Thematic Meeting - October 13-15, 2015

Biophysics of Proteins at Surfaces: Assembly, Activation, Signaling

Thursday Speaker Abstracts

High Resolution Imaging Atomic Force Microscope Study of Interactions at the Membrane-Fluid Interface Chiara Rotella 1,2 , Jason I. Kilpatrick 2 , Simona Capponi 1,2 , Miguel Holmgren 3 , Francisco Bezanilla 4 , Eduardo Perozo 4 , Suzanne P. Jarvis 1,2 . 1 School of Physics, University College Dublin, Dublin, Ireland, 2 Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland, 3 Molecular Neurophysiology Section, Porter Neuroscience Research Center, National Institute of Health, Bethesda, MD, USA, 4 Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA. The cell membrane is essential for all living systems, serving as a barrier between cells and their environment. It is typically composed of a lipid bilayer, containing embedded and/or anchored proteins that mediate different biological function such as energy conversion, signal transduction and solute transport [1]. To elucidate the basic structure of biological membranes it is necessary to make direct experimental observations of the molecular organization of the protein and lipid bilayer under physiologically relevant conditions. Using a bespoke high resolution Atomic Force Microscopy (AFM) it is possible to characterize the structure and function of both native and model lipid membranes with embedded proteins [2]. During this study we focus our attention on transmembrane MvP voltage-gated potassium channels embedded in a lipid bilayer, which are activated by changes in transmembrane potential [3]. High resolution AFM images of the membrane channel reveal the predicted tetrameric channel structure of the ion channel. Interestingly, we observed the formation of an asymmetric depression in the supporting lipid membrane surrounding the channel. This may be due to an alteration in the lipid bilayer structure to accommodate the ion channel. Using AFM is possible to investigate the interactions between proteins and membrane- liquid interface [4], [5] aiding our understanding and leading to future therapeutic application. References [1] D. J. Muller et al., Nature protocols , vol. 2, no. 9, pp. 2191--2197, 2007 . [2] A. Sumino et al., Scientific reports , vol. 3, 2013 . [3] A. M. Randich et al., Biochemistry , vol. 53, pp. 1627--1636, 2014 . [4] K. H. Sheikh and S. P. Jarvis, Journal of the American Chemical Society , vol. 133, pp. 18296--18303, 2011 . [5] U. M. Feber et al., Eur Biophys , vol. 40, pp. 329-338, 2011 .

45