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Published on: January 10, 2011
Conformational exchange in the potassium channel blocker ShK
Naoto Iwakawa1,2, Nicola J Baxter2, Dorothy C C Wai3
1Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku Katsura, Nishikyo-Ku, Kyoto, 615-8510, Japan.
High hydrostatic pressure reveals the active structure of ShK, a sea anemone peptide blocking potassium channels. This conformational insight aids in developing treatments for autoimmune diseases like psoriasis.
Area of Science:
- Biophysics
- Structural Biology
- Pharmacology
Background:
- ShK is a sea anemone peptide that blocks Kv1.1 and Kv1.3 potassium channels.
- An optimized ShK analogue is in clinical trials for autoimmune diseases.
- ShK's functional conformational exchange has been difficult to characterize.
Purpose of the Study:
- To characterize the functional conformational exchange of ShK.
- To identify the structural changes associated with ShK's active state.
- To understand how ShK binds to Kv1.3 potassium channels.
Main Methods:
- Utilized high hydrostatic pressure to stabilize ShK's alternative state.
- Monitored chemical shift changes under varying pressure.
- Employed molecular dynamics simulations to interpret structural data.
Main Results:
- Identified distinct low- and high-pressure states of ShK.
- Localized structural changes primarily to the Cys17-Cys32 disulfide bond.
- Observed alterations in the Lys22-Tyr23 pair and the 21-24 helix, increasing Lys22 solvent exposure.
Conclusions:
- High pressure effectively probes ShK's functional conformational states.
- The Cys17-Cys32 disulfide conformation is critical for ShK's activity.
- Structural insights provide a basis for designing more potent Kv1.3 channel blockers.
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