Molecular mechanisms of centipede toxin SsTx-4 inhibition of inwardly rectifying potassium channels.
Molecular mechanisms of centipede toxin SsTx-4 inhibition of inwardly rectifying potassium channels.
复制标题
蜈蚣毒素SsTx-4抑制内向整流钾通道的分子机制
DOI：
10.1016/j.jbc.2021.101076
复制
发表时间：
2021-09
期刊：
影响因子：
--
通讯作者：
Liu Z
中科院分区：
文献类型：
--
作者：
Tang D;Xu J;Li Y;Zhao P;Kong X;Hu H;Liang S;Tang C;Liu Z
内向整流钾通道(KIR)是重要的药物靶点，Kir1.1、Kir4.1和胰腺Kir6.2/SUR1通道的拮抗剂分别是治疗高血压、抑郁症和糖尿病的潜在候选药物。然而，作用于KIRS的多肽毒素很少被识别，它们的相互作用机制在很大程度上仍然难以捉摸。在这里，我们证明了蜈蚣毒素SsTx-4有效地抑制了Kir1.1、Kir4.1和Kir6.2/SUR1通道的纳微摩尔亲和力，并利用膜片钳分析和定点突变深入研究了毒素-通道相互作用的分子基础。其他KIR包括Kir2.1~2.4、Kir4.2和Kir7.1对SsTx-4具有抗性。此外，SsTx-4对KIR的内向和外向电流有不同程度的抑制作用，可能是由K+的“敲除”效应引起的，提示SsTx-4毒素具有物理上阻断K+传导途径的外孔阻滞剂的作用。突变分析进一步支持了这一结论，突变分析表明位于Kir6.2/ΔC26通道外前庭的M137是介导与SsTx-4相互作用的关键残基。另一方面，SsTx-4中与这些KIR通道结合的分子决定因素只有部分重叠，K13和F44是共同的关键残基。最重要的是，K11A、P15A和Y16A突变毒素对Kir6.2的亲和力和/或选择性有所提高，而R12A突变毒素对Kir4.1的亲和力增强。据我们所知，SsTx-4是第一个具有Kir4.1抑制活性的多肽毒素。本研究为设计基于SsTx-4模板分子的Kir6.2/SUR1通道特异性拮抗剂提供了有益的启示，并可能有助于开发新的降糖药物。
Inwardly rectifying potassium channels (Kirs) are important drug targets, with antagonists for the Kir1.1, Kir4.1, and pancreatic Kir6.2/SUR1 channels being potential drug candidates for treating hypertension, depression, and diabetes, respectively. However, few peptide toxins acting on Kirs are identified and their interacting mechanisms remain largely elusive yet. Herein, we showed that the centipede toxin SsTx-4 potently inhibited the Kir1.1, Kir4.1, and Kir6.2/SUR1 channels with nanomolar to submicromolar affinities and intensively studied the molecular bases for toxin–channel interactions using patch-clamp analysis and site-directed mutations. Other Kirs including Kir2.1 to 2.4, Kir4.2, and Kir7.1 were resistant to SsTx-4 treatment. Moreover, SsTx-4 inhibited the inward and outward currents of Kirs with different potencies, possibly caused by a K+ “knock-off” effect, suggesting the toxin functions as an out pore blocker physically occluding the K+-conducting pathway. This conclusion was further supported by a mutation analysis showing that M137 located in the outer vestibule of the Kir6.2/ΔC26 channel was the key residue mediating interaction with SsTx-4. On the other hand, the molecular determinants within SsTx-4 for binding these Kir channels only partially overlapped, with K13 and F44 being the common key residues. Most importantly, K11A, P15A, and Y16A mutant toxins showed improved affinity and/or selectivity toward Kir6.2, while R12A mutant toxin had increased affinity for Kir4.1. To our knowledge, SsTx-4 is the first characterized peptide toxin with Kir4.1 inhibitory activity. This study provides useful insights for engineering a Kir6.2/SUR1 channel–specific antagonist based on the SsTx-4 template molecule and may be useful in developing new antidiabetic drugs.
登录
查看更多内容
影响因子：
3.7
作者：
Hu J;Qiu S;Yang F;Cao Z;Li W;Wu Y
通讯作者：
Wu Y
影响因子：
2.9
作者：
Jin, WL;Lu, Z
通讯作者：
Lu, Z
外侧缰核中的星形胶质细胞 Kir4.1 驱动抑郁症中的神经元爆发
影响因子：
64.8
作者：
Cui, Yihui;Yang, Yan;Hu, Hailan
通讯作者：
Hu, Hailan
影响因子：
3.4
作者：
HEGINBOTHAM, L;LU, Z;MACKINNON, R
通讯作者：
MACKINNON, R
影响因子：
3.6
作者：
Bhave, Gautam;Chauder, Brian A.;Denton, Jerod S.
通讯作者：
Denton, Jerod S.