Title

Site-Directed Spin-Label EPR Spectroscopy Of M2 Protein In Lipid Bilayers Of Different Curvature Generation Propensity

Document Type

Poster Session

Publication Date

2-15-2017

Published In

Biophysical Journal

Abstract

M2 is a homotetrameric membrane protein critical to generation of membrane curvature in the budding stage of the influenza A virus life cycle. We have designed and interpreted site-directed spin-label electron paramagnetic resonance spectroscopy (SDSL-EPR) experiments on the conformation and dynamics of M2 in lipid bilayers of different propensities for membrane curvature generation. We have obtained data for full length M2 protein spin labelled at multiple sites in the C-terminal juxtamembrane region, which forms a membrane associated amphipathic helix. Continuous wave (CW) and pulsed EPR spectra provide evidence that M2 adopts two conformational states in bilayers, and that the propensity of lipids to form membranes of differing curvature dictates the relative population of these states. Multicomponent simulation of CW-EPR spectra further show lipid bilayers of the highly curved cubic phases stabilize an immobilized conformation of M2, hypothesized to be relevant for curvature generation. We have also characterized the size distribution of large unilamellar vesicles of lipids of different curvature generation propensities alone and in the presence of full-length M2 using dynamic light scattering (DLS).