The Potassium Channel Blocker ShK Toxin: Dynamics and Conformational Heterogeneity in Solution — ASN Events
  1. Schedule
  2. Session Five - Poster Session A
  3. The Potassium Channel Blocker ShK Toxin: Dynamics and Conformational Heterogeneity in Solution

The Potassium Channel Blocker ShK Toxin: Dynamics and Conformational Heterogeneity in Solution (#139)

Jeff Chang 1 , Sandeep Chhabra 1 , Inbal Sher 2 , Christine Beeton 3 , Jordan Chill 2 , Raymond Norton 1
  1. Monash University, Parkville, VIC, Australia
  2. Chemistry, Bar Ilan University, Tel Aviv, Israel
  3. Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, USA

ShK, a 35-residue peptide isolated from the sea anemone Stichodactyla helianthus, is a potent blocker of the potassium channel Kv1.3. The disease-relevant TEM cells (effector-memory T cells) from multiple sclerosis (MS) patients express high levels of Kv1.3 channels, blockade of which by ShK inhibits T-cell proliferation and ameliorate the disease in animal model [1]. Therefore it is possible to selectively suppress the TEM cells with a Kv1.3-specific inhibitor without compromising other immune responses. This makes ShK a valuable therapeutic lead. In order to advance the current structure-based design of ShK analogues with high Kv1.3-specificity, we have established an expression system [2] that allows efficient uniform isotope labelling for NMR studies. The chimeric KcsA channel (In Which residues 374-386 in the Shaker channel follows the Kv1.3 sequence) was used in the NMR studies [3]. NMR spectra of channel-bound isotope-labelled ShK were acquired and significant changes in chemical shifts between the bound and free spectra were observed, suggesting some structural changes. To gain a better understanding of the conformational space available to ShK in solution, backbone 15N relaxation parameters, including 15N relaxation dispersion measurements, have been undertaken. The local dynamics may affect how ShK binds to the potassium channel as binding presumably locks the peptide into one of the exchanging conformations. In conclusion, the results will be invaluable in refining our understanding of the interaction between ShK and the target Kv1.3, leading to the design of novel ShK analogues with increased specificity for Kv1.3. New analogues with high Kv1.3-specificity will serve as potential therapeutics for MS.

  1. Beeton, C., et al., Kv1.3 channels are a therapeutic target for T cell-mediated autoimmune diseases. Proc Natl Acad Sci U S A, 2006. 103(46): p. 17414-9.
  2. Chang, S.C., et al., Expression and isotopic labelling of the potassium channel blocker ShK toxin as a thioredoxin fusion protein in bacteria. Toxicon, 2012. 60(5): p. 840-850.
  3. Chill, J.H., et al., NMR study of the tetrameric KcsA potassium channel in detergent micelles. Protein Sci, 2006. 15(4): p. 684-98.