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Toward a Structural View of hERG Activation by the Small-Molecule Activator ICA-105574.
Journal of Chemical Information and Modeling ( IF 5.6 ) Pub Date : 2020-01-09 , DOI: 10.1021/acs.jcim.9b00737
Eva-Maria Zangerl-Plessl 1 , Martin Berger 2 , Martina Drescher 2 , Yong Chen 2 , Wei Wu 3 , Nuno Maulide 2 , Michael Sanguinetti 3 , Anna Stary-Weinzinger 1
Affiliation  

Outward current conducted by human ether-à-go-go-related gene type 1 (hERG1) K+ channels is important for action potential repolarization in the human ventricle. Rapid, voltage-dependent inactivation greatly reduces outward currents conducted by hERG1 channels and involves conformational changes in the ion selectivity filter (SF). Recently, compounds have been found that activate hERG1 channel function by modulating gating mechanisms such as reducing inactivation. Such activating compounds could represent a novel approach to prevent arrhythmias associated with prolonged ventricular repolarization associated with inherited or acquired long QT syndrome. ICA-105574 (ICA), a 3-nitro-n-(4-phenoxyphenyl) benzamide derivative activates hERG1 by strongly attenuating pore-type inactivation. We previously mapped the putative binding site for ICA to a hydrophobic pocket located between two adjacent subunits. Here, we used the recently reported cryoelectron microscopy structures of hERG1 to elucidate the structural mechanisms by which ICA influences the stability of the SF. By combining molecular dynamics simulations, voltage-clamp electrophysiology, and the synthesis of novel ICA derivatives, we provide atomistic insights into SF dynamics and propose a structural link between the SF and S6 segments. Further, our study highlights the importance of the nitro moiety, at the meta position of the benzamide ring, for the activity of ICA and reveals that the (bio)isosteric substitution of this side chain can switch the activity to weak inhibitors. Our findings indicate that ICA increases the stability of the SF to attenuate channel inactivation, and this action requires a fine-tuned compound geometry.

中文翻译:

探索小分子激活剂 ICA-105574 激活 hERG 的结构。

人 ether-à-go-go 相关基因 1 (hERG1) K+ 通道传导的外向电流对于人心室动作电位复极化非常重要。快速、电压依赖性失活大大减少了 hERG1 通道传导的外向电流,并涉及离子选择性过滤器 (SF) 的构象变化。最近,已经发现化合物可以通过调节门控机制(例如减少失活)来激活 hERG1 通道功能。这种激活化合物可以代表一种预防心律失常的新方法,该心律失常与遗传性或获得性长QT综合征相关的心室复极延长有关。ICA-105574 (ICA) 是一种 3-硝基-n-(4-苯氧基苯基) 苯甲酰胺衍生物,通过强烈减弱孔型失活来激活 hERG1。我们之前将 ICA 的假定结合位点映射到位于两个相邻亚基之间的疏水口袋。在这里,我们使用最近报道的 hERG1 的冷冻电镜结构来阐明 ICA 影响 SF 稳定性的结构机制。通过结合分子动力学模拟、电压钳电生理学和新型 ICA 衍生物的合成,我们提供了对 SF 动力学的原子学见解,并提出了 SF 和 S6 片段之间的结构联系。此外,我们的研究强调了苯甲酰胺环间位硝基部分对于 ICA 活性的重要性,并揭示了该侧链的(生物)等排取代可以将活性转变为弱抑制剂。我们的研究结果表明 ICA 增加了 SF 的稳定性以减弱通道失活,而这种作用需要微调复合几何结构。
更新日期:2020-01-09
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