Campus Units

Chemistry

Document Type

Article

Publication Version

Accepted Manuscript

Publication Date

6-2-2009

Journal or Book Title

Biochemistry

Volume

48

Issue

27

First Page

6361

Last Page

6368

DOI

10.1021/bi900716s

Abstract

The dynamic and structural properties of membrane proteins are intimately affected by the lipid bilayer. One property of membrane proteins is uniaxial rotational diffusion, which depends on the membrane viscosity and thickness. This rotational diffusion is readily manifested in solid-state NMR spectra as characteristic line shapes and temperature-dependent line narrowing or broadening. We show here that this whole-body uniaxial diffusion is suppressed in lipid bilayers mimicking the composition of eukaryotic cell membranes, which are rich in cholesterol and sphingomyelin. We demonstrate this membrane-induced immobilization on the transmembrane peptide of the influenza A M2 (AM2-TM) proton channel protein. At physiological temperature, AM2-TM undergoes uniaxial diffusion faster than ∼105 s−1 in DLPC, DMPC, and POPC bilayers, but the motion is slowed by 2 orders of magnitude, to <103 s−1, in a cholesterol-rich virus envelope−mimetic membrane (“viral membrane”). The immobilization is manifested as near rigid-limit 2H quadrupolar couplings and 13C−1H, 15N−1H, and 13C−15N dipolar couplings for all labeled residues. The immobilization suppresses intermediate time scale broadening of the NMR spectra, thus allowing high-sensitivity and high-resolution spectra to be measured at physiological temperature. The conformation of the protein in the viral membrane is more homogeneous than in model PC membranes, as evidenced by the narrow 15N lines. The immobilization of the M2 helical bundle by the membrane composition change indicates the importance of studying membrane proteins in environments as native as possible. It also suggests that eukaryote−mimetic lipid membranes may greatly facilitate structure determination of membrane proteins by solid-state NMR.

Comments

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Biochemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see 10.1021/bi900716s. Posted with permission.

Copyright Owner

American Chemical Society

Language

en

File Format

application/pdf

Published Version

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