Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 110, Issue 32, Pages 13008-13013Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1305563110
Keywords
membrane protein; ion channel; solid-state NMR spectroscopy
Categories
Funding
- Nederlandse Organisatie voor Wetenschappelijk Onderzoek [700.56.442, 700.11.344, 700.58.102]
- Max Planck Society
- Deutsche Forschungsgemeinschaft [Be 2345/5-1, Po137, 40-1, 41-1]
- European Union Contract [Bio-NMR 261863]
- National Institutes of Health/National Institute of General Medical Sciences [GM087519]
- Hertie Foundation
- Federation of European Biochemical Societies
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Potassium (i.e., K+) channels allow for the controlled and selective passage of potassium ions across the plasma membrane via a conserved pore domain. In voltage-gated K+ channels, gating is the result of the coordinated action of two coupled gates: an activation gate at the intracellular entrance of the pore and an inactivation gate at the selectivity filter. By using solid-state NMR structural studies, in combination with electrophysiological experiments and molecular dynamics simulations, we show that the turret region connecting the outer transmembrane helix (transmembrane helix 1) and the pore helix behind the selectivity filter contributes to K+ channel inactivation and exhibits a remarkable structural plasticity that correlates to K+ channel inactivation. The transmembrane helix 1 unwinds when the K+ channel enters the inactivated state and rewinds during the transition to the closed state. In addition to well-characterized changes at the K+ ion coordination sites, this process is accompanied by conformational changes within the turret region and the pore helix. Further spectroscopic and computational results show that the same channel domain is critically involved in establishing functional contacts between pore domain and the cellular membrane. Taken together, our results suggest that the interaction between the K+ channel turret region and the lipid bilayer exerts an important influence on the selective passage of potassium ions via the K+ channel pore.
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