Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia; Biological Faculty, Lomonosov Moscow State University, Moscow, 119992, Russia.
Toxicology and Pharmacology, University of Leuven, Leuven, 3000, Belgium.
Neuropharmacology. 2018 Dec;143:228-238. doi: 10.1016/j.neuropharm.2018.09.030. Epub 2018 Sep 22.
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 K1.2. 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 K1.2 (IC ∼0.2 nM), while its activity against K1.1, K1.3, and K1.6 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 K1.2. 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 K1.2 to K1.3 resulted in the enhanced sensitivity of mutant K1.3 channels to MeKTx11-1. We conclude that MeKTx11-1 may be used as a selective tool in neurobiology.
蝎毒液是选择性高亲和力钾通道配体的无与伦比的来源。人们强烈需要此类化合物来鉴定和操纵特定通道同工型的活性。本研究的目的是获得并表征电压门控钾通道 K1.2 的特异性配体。结果，我们报告了 Mesobuthus eupeus 蝎毒液中肽 MeKTx11-1（α-KTx 1.16）对该通道同工型的显著选择性。MeKTx11-1 是 K1.2 的高亲和力阻断剂（IC∼0.2 nM），而其对 K1.1、K1.3 和 K1.6 的活性分别低 10000、330 和 45000 倍，这是通过在表达于非洲爪蟾卵母细胞的哺乳动物通道上使用电压钳技术测量的。两个取代，G9V 和 P37S，将 MeKTx11-1 转化为其天然类似物 MeKTx11-3（α-KTx 1.17），其活性降低 15 倍，对 K1.2 的选择性降低。我们重组表达了 MeKTx11-1 和 MeKTx11-3 及其突变体 MeKTx11-1(G9V)和 MeKTx11-1(P37S)，并证明点突变对选择性具有中间作用。通过毒素-通道复合物的分子建模确定了解释 MeKTx11-1 特异性的关键结构元素。证实了我们的分子建模预测，将这些元件从 K1.2 的孔区域定向转移到 K1.3 中，导致突变体 K1.3 通道对 MeKTx11-1 的敏感性增强。我们得出结论，MeKTx11-1 可作为神经生物学中的选择性工具。
