Three-dimensional architecture and gating mechanism of a K+ channel studied by EPR spectroscopy.
The transmembrane organization of a potassium channel from Streptomyces lividans has been studied using site-directed spin labeling techniques and electron paramagnetic resonance spectroscopy. In the tetrameric channel complex, two alpha-helices were identified per monomer and assigned to the amino acid sequence. Probe mobility and accessibility data clearly establish that the first helix (TM1) is located in the perimeter of the channel, showing extensive protein-lipid contacts, while the second helix (TM2) is closer to the four-fold symmetric axis of the channel, lining the intracellular vestibule. A large conformational change in the C-terminal end of TM2 was measured when comparing conditions that favor either the open or closed states. The present data suggest that the diameter of the internal vestibule increases with channel opening.
Perozo
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Department of Molecular Physiology and Biological Physics and Center for Structural Biology, University of Virginia Health Sciences Center, Charlottesville 22906-0011, USA. eperozo@virginia.edu
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Cuello
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D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000235:genetics; D004578:Electron Spin Resonance Spectroscopy; D015640:Ion Channel Gating; D008565:Membrane Proteins / Q000737:chemistry; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000737:chemistry; D015221:Potassium Channels / Q000737:chemistry* / Q000235:genetics; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D051637:Shaker Superfamily of Potassium Channels; D013302:Streptomyces
D001426:Bacterial Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D015221:Potassium Channels; D051637:Shaker Superfamily of Potassium Channels; C107790:prokaryotic potassium channel; D003545:Cysteine