3IFX

Crystal structure of the Spin-labeled KcsA mutant V48R1

Summary for 3IFX

• Entry DOI: 10.2210/pdb3ifx/pdb
• Descriptor: Voltage-gated potassium channel, POTASSIUM ION, S-[(1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)methyl] methanesulfonothioate, ... (5 entities in total)
• Functional Keywords: potassium channel, spin-labeled protein, membrane protein, cell membrane, ion transport, ionic channel, membrane, transmembrane, transport, voltage-gated channel
• Biological source: Streptomyces lividans
• Cellular location: Cell membrane; Multi-pass membrane protein: P0A334
• Total number of polymer chains: 4
• Total formula weight: 57147.72

Authors

Cieslak, J.A.,Focia, P.J.,Gross, A. (deposition date: 2009-07-26, release date: 2010-02-09, Last modification date: 2024-11-20)

Primary citation

Cieslak, J.A.,Focia, P.J.,Gross, A.
Electron Spin-Echo Envelope Modulation (ESEEM) Reveals Water and Phosphate Interactions with the KcsA Potassium Channel
Biochemistry, 49:1486-1494, 2010

PubMed Abstract: 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.

PubMed: 20092291
DOI: 10.1021/bi9016523

Experimental method

EPR
X-RAY DIFFRACTION (3.56 Å)