Maly Jan, Emigh Aiyana M, DeMarco Kevin R, Furutani Kazuharu, Sack Jon T, Clancy Colleen E, Vorobyov Igor, Yarov-Yarovoy Vladimir
Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA, United States.
Biophysics Graduate Group, University of California, Davis, Davis, CA, United States.
Front Pharmacol. 2022 Sep 16;13:966463. doi: 10.3389/fphar.2022.966463. eCollection 2022.
The voltage-gated potassium channel, K11.1, encoded by the human -Related Gene (hERG), is expressed in cardiac myocytes, where it is crucial for the membrane repolarization of the action potential. Gating of the hERG channel is characterized by rapid, voltage-dependent, C-type inactivation, which blocks ion conduction and is suggested to involve constriction of the selectivity filter. Mutations S620T and S641A/T within the selectivity filter region of hERG have been shown to alter the voltage dependence of channel inactivation. Because hERG channel blockade is implicated in drug-induced arrhythmias associated with both the open and inactivated states, we used Rosetta to simulate the effects of hERG S620T and S641A/T mutations to elucidate conformational changes associated with hERG channel inactivation and differences in drug binding between the two states. Rosetta modeling of the S641A fast-inactivating mutation revealed a lateral shift of the F627 side chain in the selectivity filter into the central channel axis along the ion conduction pathway and the formation of four lateral fenestrations in the pore. Rosetta modeling of the non-inactivating mutations S620T and S641T suggested a potential molecular mechanism preventing F627 side chain from shifting into the ion conduction pathway during the proposed inactivation process. Furthermore, we used Rosetta docking to explore the binding mechanism of highly selective and potent hERG blockers - dofetilide, terfenadine, and E4031. Our structural modeling correlates well with much, but not all, existing experimental evidence involving interactions of hERG blockers with key residues in hERG pore and reveals potential molecular mechanisms of ligand interactions with hERG in an inactivated state.
由人类相关基因（hERG）编码的电压门控钾通道K11.1在心肌细胞中表达，对动作电位的膜复极化至关重要。hERG通道的门控具有快速、电压依赖性的C型失活特征，这种失活会阻断离子传导，提示其涉及选择性过滤器的收缩。hERG选择性过滤器区域内的S620T和S641A/T突变已被证明会改变通道失活的电压依赖性。由于hERG通道阻断与开放和失活状态下的药物性心律失常有关，我们使用Rosetta来模拟hERG S620T和S641A/T突变的影响，以阐明与hERG通道失活相关的构象变化以及两种状态下药物结合的差异。S641A快速失活突变的Rosetta建模显示，选择性过滤器中F627侧链沿离子传导途径向中央通道轴横向移动，并在孔中形成四个横向小孔。非失活突变S620T和S641T的Rosetta建模提示了一种潜在的分子机制，可防止F627侧链在拟议的失活过程中移入离子传导途径。此外，我们使用Rosetta对接来探索高选择性和强效hERG阻滞剂——多非利特、特非那定和E4031的结合机制。我们的结构建模与许多（但不是全部）现有的涉及hERG阻滞剂与hERG孔中关键残基相互作用的实验证据密切相关，并揭示了配体与失活状态下hERG相互作用的潜在分子机制。
