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Structure. 2011 Nov 9;19(11):1549-61. doi: 10.1016/j.str.2011.10.009.

Toward the fourth dimension of membrane protein structure: insight into dynamics from spin-labeling EPR spectroscopy.

Author information

1
Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA. hassane.mchaourab@vanderbilt.edu

Abstract

Trapping membrane proteins in the confines of a crystal lattice obscures dynamic modes essential for interconversion between multiple conformations in the functional cycle. Moreover, lattice forces could conspire with detergent solubilization to stabilize a minor conformer in an ensemble thus confounding mechanistic interpretation. Spin labeling in conjunction with electron paramagnetic resonance (EPR) spectroscopy offers an exquisite window into membrane protein dynamics in the native-like environment of a lipid bilayer. Systematic application of spin labeling and EPR identifies sequence-specific secondary structures, defines their topology and their packing in the tertiary fold. Long range distance measurements (60 Å-80 Å) between pairs of spin labels enable quantitative analysis of equilibrium dynamics and triggered conformational changes. This review highlights the contribution of spin labeling to bridging structure and mechanism. Efforts to develop methods for determining structures from EPR restraints and to increase sensitivity and throughput promise to expand spin labeling applications in membrane protein structural biology.

PMID:
22078555
PMCID:
PMC3224804
DOI:
10.1016/j.str.2011.10.009
[Indexed for MEDLINE]
Free PMC Article

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