N-Terminally extended analogues of the K⁺ channel toxin from Stichodactyla helianthus as potent and selective blockers of the voltage-gated potassium channel Kv1.3

FEBS J. 2015 Jun;282(12):2247-59. doi: 10.1111/febs.13294. Epub 2015 Apr 23.

Abstract

The voltage-gated potassium channel Kv1.3 is an important target for the treatment of autoimmune diseases and asthma. Blockade of Kv1.3 by the sea anemone peptide K⁺-channel toxin from Stichodactyla helianthus (ShK) inhibits the proliferation of effector memory T lymphocytes and ameliorates autoimmune diseases in animal models. However, the lack of selectivity of ShK for Kv1.3 over the Kv1.1 subtype has driven a search for Kv1.3-selective analogues. In the present study, we describe N-terminally extended analogues of ShK that contain a negatively-charged Glu, designed to mimic the phosphonate adduct in earlier Kv1.3-selective analogues, and consist entirely of common protein amino acids. Molecular dynamics simulations indicated that a Trp residue at position [-3] of the tetrapeptide extension could form stable interactions with Pro377 of Kv1.3 and best discriminates between Kv1.3 and Kv1.1. This led to the development of ShK with an N-terminal Glu-Trp-Ser-Ser extension ([EWSS]ShK), which inhibits Kv1.3 with an IC₅₀ of 34 pm and is 158-fold selective for Kv1.3 over Kv1.1. In addition, [EWSS]ShK is more than 2900-fold more selective for Kv1.3 over Kv1.2 and KCa3.1 channels. As a highly Kv1.3-selective analogue of ShK based entirely on protein amino acids, which can be produced by recombinant expression, this peptide is a valuable addition to the complement of therapeutic candidates for the treatment of autoimmune diseases.

Keywords: N-terminal extension; ShK; electrophysiology; molecular dynamics; potassium channels.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Inflammatory Agents, Non-Steroidal / chemistry
  • Anti-Inflammatory Agents, Non-Steroidal / metabolism
  • Anti-Inflammatory Agents, Non-Steroidal / pharmacology*
  • Binding Sites
  • Cell Line
  • Cnidarian Venoms*
  • Drug Design*
  • Isoenzymes / antagonists & inhibitors
  • Isoenzymes / chemistry
  • Isoenzymes / metabolism
  • Kinetics
  • Kv1.3 Potassium Channel / antagonists & inhibitors*
  • Kv1.3 Potassium Channel / chemistry
  • Kv1.3 Potassium Channel / genetics
  • Kv1.3 Potassium Channel / metabolism
  • Mice
  • Models, Molecular*
  • Molecular Dynamics Simulation
  • Mutant Proteins / chemistry
  • Mutant Proteins / metabolism
  • Mutant Proteins / pharmacology*
  • Neurotoxins / chemistry
  • Neurotoxins / genetics
  • Neurotoxins / metabolism
  • Neurotoxins / pharmacology
  • Oligopeptides / chemistry
  • Oligopeptides / genetics
  • Oligopeptides / metabolism
  • Oligopeptides / pharmacology
  • Patch-Clamp Techniques
  • Potassium Channel Blockers / chemistry
  • Potassium Channel Blockers / metabolism
  • Potassium Channel Blockers / pharmacology*
  • Protein Conformation
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / metabolism
  • Recombinant Fusion Proteins / pharmacology
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Sea Anemones
  • Structure-Activity Relationship

Substances

  • Anti-Inflammatory Agents, Non-Steroidal
  • Cnidarian Venoms
  • Isoenzymes
  • Kcna3 protein, mouse
  • Kv1.3 Potassium Channel
  • Mutant Proteins
  • Neurotoxins
  • Oligopeptides
  • Potassium Channel Blockers
  • Recombinant Fusion Proteins
  • Recombinant Proteins