钾通道在调节许多生理过程中起关键作用,因此,它们正常功能的改变会导致几种疾病的发展。因此,寻找能够调节这些通道活性的化合物构成了一个紧张的研究领域。钾蝎子毒素分为六个亚家族(α,β,γ,κ,δ,和λ)。然而,缺乏长链β-KTx亚家族的实验结构和功能分析。因此,在这项研究中,我们重组产生了存在于Tityuscostatus和Lychasmucronatus蝎子毒液中的毒素TcoKIK和β-KTx14.3,分别。通过核磁共振确定这些β-KTx毒素的3D结构。在这两种毒素中,N端区域是非结构化的,而C端具有经典的CSα/β基序。TcoKIK对青蛙振动筛和人类KCNQ1钾通道没有任何明显的活性;然而,β-KTx14.3能够阻断KCNQ1通道。使用分子动力学模拟研究了毒素-通道相互作用模式。结果表明,该毒素可以与KCNQ1形成稳定的极性-极性和疏水相互作用网络,涉及两个分子伴侣中的关键保守残基。能够抑制KCNQ1的毒素的发现和表征为未来开发用于治疗由这种钾通道功能失调引起的人类疾病的新型药物铺平了道路。重要声明:蝎子毒素已被证明很少阻断人类KCNQ1通道,参与心脏过程的调节。在这项研究中,我们获得了重组β-KTx14.3和TcoKIK毒素,并通过核磁共振确定了它们的3D结构。然后采用电生理研究和分子动力学模型来检查这两种毒素与人KCNQ1之间的相互作用,人KCNQ1是心脏复极化的主要驱动通道;发现β-KTx14.3可以有效地阻断该通道。我们的发现为开发新的基于毒素的药物提供了见解,用于治疗涉及KCNQ1样通道的心脏通道病。
Potassium channels play a key role in regulating many physiological processes, thus, alterations in their proper functioning can lead to the development of several diseases. Hence, the search for compounds capable of regulating the activity of these channels constitutes an intense field of investigation. Potassium scorpion toxins are grouped into six subfamilies (α, β, γ, κ, δ, and λ). However, experimental structures and functional analyses of the long chain β-KTx subfamily are lacking. In this study, we recombinantly produced the toxins TcoKIK and beta-KTx14.3 present in the venom of Tityus costatus and Lychas mucronatus scorpions, respectively. The 3D structures of these β-KTx toxins were determined by nuclear magnetic resonance. In both toxins, the N-terminal region is unstructured, while the C-terminal possesses the classic CSα/β motif. TcoKIK did not show any clear activity against frog Shaker and human KCNQ1 potassium channels; however, beta-KTx14.3 was able to block the KCNQ1 channel. The toxin-channel interaction mode was investigated using molecular dynamics simulations. The results showed that this toxin could form a stable network of polar-to-polar and hydrophobic interactions with KCNQ1, involving key conserved residues in both molecular partners. The discovery and characterization of a toxin capable of inhibiting KCNQ1 pave the way for the future development of novel drugs for the treatment of human diseases caused by the malfunction of this potassium channel. STATEMENT OF SIGNIFICANCE: Scorpion toxins have been shown to rarely block human KCNQ1 channels, which participate in the regulation of cardiac processes. In this study, we obtained recombinant beta-KTx14.3 and TcoKIK toxins and determined their 3D structures by nuclear magnetic resonance. Electrophysiological studies and molecular dynamics models were employed to examine the interactions between these two toxins and the human KCNQ1, which is the major driver channel of cardiac repolarization; beta-KTx14.3 was found to block effectively this channel. Our findings provide insights for the development of novel toxin-based drugs for the treatment of cardiac channelopathies involving KCNQ1-like channels.