Cui, Tanxing; Mowrey, David; Bondarenko, Vasyl; Tillman, Tommy; Ma, Dejian; Landrum, Elizabeth; Perez-Aguilar, Jose Manuel; He, Jing; Wang, Wei; Saven, Jeffery G.; Eckenhoff, Roderic G.; Tang, Pei; Xu, Yan
NMR structure and dynamics of a designed water-soluble transmembrane domain of nicotinic acetylcholine receptor
BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES, 1818:617-626, MAR 2012

The nicotinic acetylcholine receptor (nAChR) is an important therapeutic target for a wide range of pathophysiological conditions, for which rational drug designs often require receptor structures at atomic resolution. Recent proof-of-concept studies demonstrated a water-solubilization approach to structure determination of membrane proteins by NMR (Slovic et al.. PNAS, 101: 1828-1833, 2004; Ma et al., PNAS, 105: 16537-42, 2008). We report here the computational design and experimental characterization of WSA, a water-soluble protein with similar to 83% sequence identity to the transmembrane (TM) domain of the nAChR alpha 1 subunit. Although the design was based on a low-resolution structural template, the resulting high-resolution NMR structure agrees remarkably well with the recent crystal structure of the TM domains of the bacterial Gloeobacter violaceus pentameric ligand-gated ion channel (GLIC), demonstrating the robustness and general applicability of the approach. NMR T-2 dispersion measurements showed that the TM2 domain of the designed protein was dynamic, undergoing conformational exchange on the NMR timescale. Photoaffinity labeling with isoflurane and propofol photolabels identified a common binding site in the immediate proximity of the anesthetic binding site found in the crystal structure of the anesthetic-GLIC complex. Our results illustrate the usefulness of high-resolution NMR analyses of water-solubilized channel proteins for the discovery of potential drug binding sites. (C) 2011 Elsevier B.V. All rights reserved.

DOI:10.1016/j.bbamem.2011.11.021

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