K V 1.2 channel-specific blocker from Mesobuthus eupeus scorpion venom: Structural basis of selectivity

Neuropharmacology. 2018 Dec;143:228-238. doi: 10.1016/j.neuropharm.2018.09.030. Epub 2018 Sep 22.

Abstract

Scorpion venom is an unmatched source of selective high-affinity ligands of potassium channels. There is a high demand for such compounds to identify and manipulate the activity of particular channel isoforms. The objective of this study was to obtain and characterize a specific ligand of voltage-gated potassium channel KV1.2. As a result, we report the remarkable selectivity of the peptide MeKTx11-1 (α-KTx 1.16) from Mesobuthus eupeus scorpion venom to this channel isoform. MeKTx11-1 is a high-affinity blocker of KV1.2 (IC50 ∼0.2 nM), while its activity against KV1.1, KV1.3, and KV1.6 is 10 000, 330 and 45 000 fold lower, respectively, as measured using the voltage-clamp technique on mammalian channels expressed in Xenopus oocytes. Two substitutions, G9V and P37S, convert MeKTx11-1 to its natural analog MeKTx11-3 (α-KTx 1.17) having 15 times lower activity and reduced selectivity to KV1.2. We produced MeKTx11-1 and MeKTx11-3 as well as their mutants MeKTx11-1(G9V) and MeKTx11-1(P37S) recombinantly and demonstrated that point mutations provide an intermediate effect on selectivity. Key structural elements that explain MeKTx11-1 specificity were identified by molecular modeling of the toxin-channel complexes. Confirming our molecular modeling predictions, site-directed transfer of these elements from the pore region of KV1.2 to KV1.3 resulted in the enhanced sensitivity of mutant KV1.3 channels to MeKTx11-1. We conclude that MeKTx11-1 may be used as a selective tool in neurobiology.

Keywords: Ion channel; Molecular dynamics; Neurotoxin; Peptides; Potassium channel; Scorpion toxin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Blattellidae
  • Humans
  • Kv1.2 Potassium Channel / antagonists & inhibitors*
  • Kv1.2 Potassium Channel / metabolism
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Molecular Dynamics Simulation
  • Mutagenesis, Site-Directed
  • Neurotoxins / chemistry
  • Neurotoxins / pharmacology
  • Oocytes
  • Patch-Clamp Techniques
  • Potassium Channel Blockers / chemistry
  • Potassium Channel Blockers / pharmacology*
  • Rats
  • Recombinant Proteins
  • Scorpions
  • Structure-Activity Relationship
  • Xenopus laevis

Substances

  • Kv1.2 Potassium Channel
  • Neurotoxins
  • Potassium Channel Blockers
  • Recombinant Proteins