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Structures of Gating Intermediates in a K+ channel
Ravikumar Reddi1, Kimberly Matulef2, Erika Riederer2
1Program in Chemical Biology, Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, OR 97239, United States. Electronic address: https://twitter.com/Ravi_K_Reddi.
Journal of Molecular Biology
|October 10, 2021
Summary
Studies on a KcsA channel mutant reveal how ion conduction is regulated. Altered ion occupancy at the S2 site is crucial for potassium (K+) channel inactivation.
Area of Science:
- Biophysics
- Structural Biology
- Molecular Biology
Background:
- Potassium (K+) channel function relies on coordinated activation and inactivation gates.
- Understanding the allosteric coupling between these gates is critical for channel regulation.
Purpose of the Study:
- To investigate the allosteric coupling mechanism in K+ channels.
- To elucidate the role of a conserved W67 residue in KcsA channel gating.
Main Methods:
- Utilized continuous wave Electron Paramagnetic Resonance (EPR) spectroscopy.
- Performed structural studies on a W67F mutant KcsA channel.
- Analyzed pH dependence of channel activation.
Main Results:
- The W67F mutation significantly reduced KcsA channel inactivation and increased activation rates.
- EPR revealed an altered pH dependence of activation for the W67F mutant.
- Structural analysis identified pre-open and pre-inactivated intermediate states.
- Open-state structures showed altered ion occupancy at the S2 site.
Conclusions:
- The W67F mutation provides insights into K+ channel allosteric gating.
- Ion occupancy at the S2 site is essential for K+ channel inactivation.
- Key nodes in the allosteric pathway were identified through intermediate state structures.
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