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Structure and physiological function of the human KCNQ1 channel voltage sensor intermediate state
Keenan C Taylor1,2, Po Wei Kang3, Panpan Hou3
1Department of Biochemistry, Vanderbilt University, Nashville, United States.
Elife
|February 26, 2020
Summary
Researchers determined the intermediate structure of the human KCNQ1 voltage-gated potassium channel voltage sensor domain. This finding reveals how KCNQ1 channels contribute to cardiac and epithelial functions.
Area of Science:
- Molecular Biology
- Biophysics
- Structural Biology
Background:
- Voltage-gated ion channels are crucial for cellular electrical signaling.
- Their voltage sensor domains (VSDs) cycle through resting, intermediate, and activated states.
- The intermediate VSD conformation structure has been difficult to determine experimentally.
Purpose of the Study:
- To determine the three-dimensional structure of the human KCNQ1 VSD in its intermediate state.
- To functionally map the determinants of S4 helix motion during channel activation.
- To demonstrate the physiological relevance of intermediate state KCNQ1 conductance.
Main Methods:
- Experimental determination of the KCNQ1 VSD intermediate state structure.
- Site-directed mutagenesis and electrophysiology in Xenopus laevis oocytes.
- Voltage-clamp fluorometry.
Main Results:
- The first experimental 3D structure of the human KCNQ1 VSD in the intermediate state was determined.
- Key determinants of S4 helix movement from the intermediate to the activated state were identified.
- Intermediate state conductance was shown to contribute to KCNQ1 channel function.
Conclusions:
- This study elucidates the structure of the VSD intermediate state for KCNQ1.
- The intermediate state's conductivity is vital for KCNQ1's dual role in cardiac (IKs) and epithelial currents.
- Understanding this state provides insights into ion channel gating mechanisms and versatility.
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