Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, CU, Ciudad de México 04510, Mexico.
Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center, Houston, TX 77030, USA.
Biochim Biophys Acta Proteins Proteom. 2023 Jul 1;1871(4):140906. doi: 10.1016/j.bbapap.2023.140906. Epub 2023 Mar 12.
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.
钾通道在调节许多生理过程中起着关键作用，因此，它们正常功能的改变可能导致多种疾病的发展。因此，寻找能够调节这些通道活性的化合物是一个研究热点。钾通道蝎毒素分为六个亚家族（α、β、γ、κ、δ 和 λ）。然而，长链β-KTx 亚家族的实验结构和功能分析尚缺乏。在这项研究中，我们重组表达了 Tityus costatus 和 Lychas mucronatus 蝎毒液中的 TcoKIK 和 beta-KTx14.3 毒素。通过核磁共振确定了这些β-KTx 毒素的三维结构。在这两种毒素中，N 端区域无结构，而 C 端具有经典的 CSα/β 基序。TcoKIK 对蛙 Shaker 和人 KCNQ1 钾通道没有明显的活性；然而，beta-KTx14.3 能够阻断 KCNQ1 通道。通过分子动力学模拟研究了毒素-通道相互作用模式。结果表明，这种毒素可以与 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。发现并表征了一种能够抑制 KCNQ1 的毒素，为未来开发治疗 KCNQ1 钾通道功能障碍引起的人类疾病的新型药物铺平了道路。
蝎毒素已被证明很少能阻断人类 KCNQ1 通道，该通道参与心脏过程的调节。在这项研究中，我们获得了重组 beta-KTx14.3 和 TcoKIK 毒素，并通过核磁共振确定了它们的 3D 结构。电生理学研究和分子动力学模型用于研究这两种毒素与人类 KCNQ1（主要是心脏复极化的驱动通道）之间的相互作用，发现 beta-KTx14.3 能有效阻断该通道。我们的研究结果为开发基于新型毒素的药物提供了新的思路，用于治疗涉及 KCNQ1 样通道的心脏通道病。
