3IFX : Crystal structure of the Spin-labeled KcsA mutant V48R1

  • John A. Cieslak (Contributor)
  • Pamela J Focia (Contributor)
  • Adrian Gross (Contributor)



Experimental Technique/Method:X-RAY DIFFRACTION, EPR
Release Date:2010-02-09
Deposition Date:2009-07-26
Revision Date:2011-07-13#2011-07-27
Molecular Weight:57147.72
Macromolecule Type:Protein
Residue Count:516
Atom Site Count:2829

Electron spin-echo envelope modulation (ESEEM) spectroscopy is a well-established technique for the study of naturally occurring paramagnetic metal centers. The technique has been used to study copper complexes, hemes, enzyme mechanisms, micellar water content, and water permeation profiles in membranes, among other applications. In the present study, we combine ESEEM spectroscopy with site-directed spin labeling (SDSL) and X-ray crystallography in order to evaluate the technique's potential as a structural tool to describe the native environment of membrane proteins. Using the KcsA potassium channel as a model system, we demonstrate that deuterium ESEEM can detect water permeation along the lipid-exposed surface of the KcsA outer helix. We further demonstrate that (31)P ESEEM is able to identify channel residues that interact with the phosphate headgroup of the lipid bilayer. In combination with X-ray crystallography, the (31)P data may be used to define the phosphate interaction surface of the protein. The results presented here establish ESEEM as a highly informative technique for SDSL studies of membrane proteins.
Date made available2010

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