2. Academic Validation
  3. A potent and Kv1.3-selective analogue of the scorpion toxin HsTX1 as a potential therapeutic for autoimmune diseases

A potent and Kv1.3-selective analogue of the scorpion toxin HsTX1 as a potential therapeutic for autoimmune diseases

  • Sci Rep. 2014 Mar 28:4:4509. doi: 10.1038/srep04509.
M Harunur Rashid 1,  Redwan Huq 2,  Mark R Tanner 3,  Sandeep Chhabra 4,  Keith K Khoo 4,  Rosendo Estrada 5,  Vikas Dhawan 5,  Satendra Chauhan 5,  Michael W Pennington 5,  Christine Beeton 6,  Serdar Kuyucak 7,  Raymond S Norton 4
Affiliations

Affiliations

  • 1 1] Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia [2] School of Physics, University of Sydney, New South Wales 2006, Australia.
  • 2 1] Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA [2] Graduate Program in Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.
  • 3 1] Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA [2] Interdepartmental Graduate Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
  • 4 Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia.
  • 5 Peptides International, 11621 Electron Drive, Louisville, KY 40299, USA.
  • 6 Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.
  • 7 School of Physics, University of Sydney, New South Wales 2006, Australia.
PMID: 24676092 DOI: 10.1038/srep04509
Abstract

HsTX1 toxin, from the scorpion Heterometrus spinnifer, is a 34-residue, C-terminally amidated peptide cross-linked by four disulfide bridges. Here we describe new HsTX1 analogues with an Ala, Phe, Val or Abu substitution at position 14. Complexes of HsTX1 with the voltage-gated potassium channels Kv1.3 and Kv1.1 were created using docking and molecular dynamics simulations, then umbrella sampling simulations were performed to construct the potential of mean force (PMF) of the ligand and calculate the corresponding binding free energy for the most stable configuration. The PMF method predicted that the R14A mutation in HsTX1 would yield a > 2 kcal/mol gain for the Kv1.3/Kv1.1 selectivity free energy relative to the wild-type peptide. Functional assays confirmed the predicted selectivity gain for HsTX1[R14A] and HsTX1[R14Abu], with an affinity for Kv1.3 in the low picomolar range and a selectivity of more than 2,000-fold for Kv1.3 over Kv1.1. This remarkable potency and selectivity for Kv1.3, which is significantly up-regulated in activated effector memory cells in humans, suggest that these analogues represent valuable leads in the development of therapeutics for autoimmune diseases.

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