1. K V 1.2 channel-specific blocker from Mesobuthus eupeus scorpion venom: Structural basis of selectivity.
- Author
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Kuzmenkov AI, Nekrasova OV, Peigneur S, Tabakmakher VM, Gigolaev AM, Fradkov AF, Kudryashova KS, Chugunov AO, Efremov RG, Tytgat J, Feofanov AV, and Vassilevski AA
- Subjects
- Amino Acid Sequence, Animals, Blattellidae, Humans, 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, Rats, Recombinant Proteins, Scorpions, Structure-Activity Relationship, Xenopus laevis, Kv1.2 Potassium Channel antagonists & inhibitors, Potassium Channel Blockers pharmacology
- 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 K
V 1.2. 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 KV 1.2 (IC50 ∼0.2 nM), while its activity against KV 1.1, KV 1.3, and KV 1.6 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 KV 1.2. 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 KV 1.2 to KV 1.3 resulted in the enhanced sensitivity of mutant KV 1.3 channels to MeKTx11-1. We conclude that MeKTx11-1 may be used as a selective tool in neurobiology., (Copyright © 2018 Elsevier Ltd. All rights reserved.)- Published
- 2018
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