Mechanism of activation at the selectivity filter of the KcsA K+ channel
Abstract
Potassium channels are opened by ligands and/or membrane potential. In voltage-gated K+ channels and the prokaryotic KcsA channel, conduction is believed to result from opening of an intracellular constriction that prevents ion entry into the pore. On the other hand, numerous ligand-gated K+ channels lack such gate, suggesting that they may be activated by a change within the selectivity filter, a narrow region at the extracellular side of the pore. Using molecular dynamics simulations and electrophysiology measurements, we show that ligand-induced conformational changes in the KcsA channel removes steric restraints at the selectivity filter, thus resulting in structural fluctuations, reduced K+ affinity, and increased ion permeation. Such activation of the selectivity filter may be a universal gating mechanism within K+ channels. The occlusion of the pore at the level of the intracellular gate appears to be secondary.
Article and author information
Author details
Funding
Swiss National Science Foundation (SNF Professorship No PP00P3_139205)
- Simon Bernèche
FP7 European Union (Human Brain Project No 604102)
- Simon Bernèche
NIH Office of the Director (R01GM088352)
- Crina M Nimigean
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Kenton J Swartz, National Institutes of Health, United States
Version history
- Received: February 8, 2017
- Accepted: October 5, 2017
- Accepted Manuscript published: October 10, 2017 (version 1)
- Version of Record published: November 3, 2017 (version 2)
Copyright
© 2017, Heer et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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