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Solution structure of the HsapBK K+ channel voltage-sensor paddle sequence.
Sofia Unnerståle1, Jesper Lind, Evangelos Papadopoulos
1Department of Biochemistry and Biophysics, Center for Biomembrane Research, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.
Biochemistry
|May 22, 2009
Summary
Researchers determined the NMR structure of a key voltage-sensor fragment from the HsapBK potassium channel. This reveals a helix-turn-helix motif, aiding understanding of potassium channel gating mechanisms.
Area of Science:
- Structural Biology
- Biophysics
- Molecular Neuroscience
Background:
- Voltage-gated potassium channels are crucial for regulating cell membrane potential.
- The S3b-S4 segment forms the voltage-sensor paddle, mediating channel gating.
- Understanding the structure of this fragment is key to elucidating channel function.
Purpose of the Study:
- To determine the NMR solution structure of the S3b-S4 voltage-sensor fragment of the HsapBK potassium channel.
- To investigate the interaction between the S3b-S4 fragment and dodecylphosphocholine (DPC) micelles.
- To compare the structure with other voltage-gated potassium channels.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy, including PFG NMR for diffusion coefficient determination.
- Solution structure determination of the peptide-DPC complex.
- Analysis of secondary structure motifs and residue positioning.
Main Results:
- The first structure of the S3b-S4 fragment from a BK channel was determined.
- A well-defined complex between the S3b-S4 peptide and DPC micelles was confirmed.
- A helix-turn-helix motif was observed, consistent with crystal structures of other K(v) channels.
- Critical arginine residues were found on the surface, similar to K(v) channels.
Conclusions:
- The S3b-S4 fragment of HsapBK potassium channel adopts a stable structure in DPC micelles.
- The determined structure provides insights into the voltage-sensing mechanism of BK channels.
- Structural similarities and differences with K(v) channels may explain variations in paddle movement and gating.
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