The isolated voltage sensing domain of the Shaker potassium channel forms a voltage-gated cation channel
Abstract
Domains in macromolecular complexes are often considered structurally and functionally conserved while energetically coupled to each other. In the modular voltage-gated ion channels the central ion-conducting pore is surrounded by four voltage sensing domains (VSDs). Here, the energetic coupling is mediated by interactions between the S4-S5 linker, covalently linking the domains, and the proximal C-terminus. In order to characterize the intrinsic gating of the voltage sensing domain in the absence of the pore domain, the Shaker Kv channel was truncated after the 4th transmembrane helix S4 (Shaker-iVSD). Shaker-iVSD showed significantly altered gating kinetics and formed a cation-selective ion channel with a strong preference for protons. Ion conduction in Shaker-iVSD developed despite identical primary sequence, indicating an allosteric influence of the pore domain. Shaker-iVSD also displays pronounced 'relaxation'. Closing of the pore correlates with entry into relaxation suggesting that the two processes are energetically related.
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Author details
Funding
Canadian Institutes of Health Research (MOP-136894)
- Rikard Blunck
Natural Sciences and Engineering Research Council of Canada (DG- 327201-2012)
- Rikard Blunck
Canadian Institutes of Health Research (MOP-102689)
- Rikard Blunck
Natural Sciences and Engineering Research Council of Canada (CDMC-CREATE postdoctoral fellowship)
- Juan Zhao
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: This study was performed in strict accordance with the guidelines of the CDEA of Université de Montréal (licence No. 16-033).
Copyright
© 2016, Zhao & Blunck
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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