Boiteux Céline, Vorobyov Igor, French Robert J, French Christopher, Yarov-Yarovoy Vladimir, Allen Toby W
School of Applied Sciences and Health Innovations Research Institute, RMIT University, Melbourne, VIC 3001, Australia;
Department of Chemistry, University of California, Davis, CA 95616;
Proc Natl Acad Sci U S A. 2014 Sep 9;111(36):13057-62. doi: 10.1073/pnas.1408710111. Epub 2014 Aug 18.
Voltage-gated sodium (Nav) channels are important targets in the treatment of a range of pathologies. Bacterial channels, for which crystal structures have been solved, exhibit modulation by local anesthetic and anti-epileptic agents, allowing molecular-level investigations into sodium channel-drug interactions. These structures reveal no basis for the "hinged lid"-based fast inactivation, seen in eukaryotic Nav channels. Thus, they enable examination of potential mechanisms of use- or state-dependent drug action based on activation gating, or slower pore-based inactivation processes. Multimicrosecond simulations of NavAb reveal high-affinity binding of benzocaine to F203 that is a surrogate for FS6, conserved in helix S6 of Domain IV of mammalian sodium channels, as well as low-affinity sites suggested to stabilize different states of the channel. Phenytoin exhibits a different binding distribution owing to preferential interactions at the membrane and water-protein interfaces. Two drug-access pathways into the pore are observed: via lateral fenestrations connecting to the membrane lipid phase, as well as via an aqueous pathway through the intracellular activation gate, despite being closed. These observations provide insight into drug modulation that will guide further developments of Nav inhibitors.
电压门控钠（Nav）通道是一系列疾病治疗中的重要靶点。已解析出晶体结构的细菌通道表现出受局部麻醉剂和抗癫痫药物的调制作用，这使得能够在分子水平上研究钠通道与药物的相互作用。这些结构并未揭示真核Nav通道中基于“铰链盖”的快速失活的基础。因此，它们能够基于激活门控或基于孔的较慢失活过程来研究使用依赖性或状态依赖性药物作用的潜在机制。对NavAb的多微秒模拟显示，苯佐卡因与F203具有高亲和力结合，F203是FS6的替代物，在哺乳动物钠通道结构域IV的螺旋S6中保守，同时还存在低亲和力位点，这些位点被认为可稳定通道的不同状态。由于苯妥英在膜与水 - 蛋白质界面处的优先相互作用，其表现出不同的结合分布。观察到两种进入孔道的药物途径：一种是通过连接到膜脂质相的侧向小孔，另一种是通过细胞内激活门的水性途径，尽管激活门处于关闭状态。这些观察结果为药物调制提供了见解，将指导Nav抑制剂的进一步开发。
