Mechanism of BK Channel Gating

我们的长期目标是了解BK通道激活的分子机制。BK型K+ 通道被电压和细胞内Ca 2+激活。这些通道在调节肌肉中很重要 收缩，神经传输和昼夜节律起搏器输出，并已被证明与 高血压、精神分裂症、癫痫和阵发性运动障碍。这些渠道正在进行， 神经元缺血、创伤和认知能力下降的治疗靶点。电压传感器和Ca 2+结合 已确定BK通道中的站点。然而，传感器之间的耦合的结构基础和 位于不同结构域中的激活门仍然难以捉摸。的一个中心问题 BK通道门控的关键步骤是这些不同的结构域如何相互作用， 调节传感器和激活门之间的耦合。这项提议的动机是长期以来- 期待和最近解决了整个BK通道的原子结构。这些结构提供了新的见解， 传感器-孔耦合的基本机制可能不同于先前的理解。的 结构和功能的研究导致了回答这个问题的一般假设： 电压传感器结构域（VSD）、胞质结构域（CTD）和孔-门结构域（PGD）都起作用 到传感器-孔隙耦合。我们提出了三个具体的目标来检验这一假设的三个关键方面： 1)VSD-孔耦合中的VSD-PGD相互作用，2）VSD-孔和Ca ~（2+）-孔中的VSD-CTD相互作用， 孔偶联，以及3）PGD和CTD之间的肽接头在VSD孔和Ca 2+孔中的作用 联轴节.我们将使用新的基于结构的筛选方法来鉴定调节通道的化合物， 功能通道蛋白中的这些化合物和突变将作为探针来指示结构性的蛋白质。 这些基序是BK通道中传感器-孔耦合的关键。研究突变的生物物理学， 调节剂到通道结构上将使我们能够理解 生理刺激打开BK通道。这些研究的结果将确定新的结合位点，化学 药物改变通道功能的核心和新机制，这将直接帮助药物开发 目标是BK频道我们对BK通道的研究可能为了解其他离子通道提供了新的思路 具有相似结构和功能特征的通道。

Our long-term goal is to understand the molecular mechanisms of BK channel activation. BK-type K+ channels are activated by voltage and intracellular Ca2+. These channels are important in modulating muscle contraction, neural transmission and circadian pacemaker output, and have been shown to associate with hypertension, schizophrenia, epilepsy and paroxysmal dyskinesia. These channels are being pursued as therapeutic targets for neuronal ischemia, trauma and cognitive decline. The voltage sensor and Ca2+ binding sites in BK channels have been identified. However, the structural basis for the coupling between sensors and the activation gate, which are located in different structural domains, still remains elusive. A central question in this crucial step of BK channel gating is how these different structural domains interact with one another to mediate the coupling between the sensors and the activation gate. This proposal is motivated by the long- awaited and recently solved atomic structures of a whole BK channel. These structures offer new insights on fundamental mechanisms of sensor-pore coupling that may differ from the previous understanding. The structure and functional studies lead to a general hypothesis for answering this question: interactions among the voltage sensor domain (VSD), the cytosolic domain (CTD), and the pore-gate domain (PGD) all contribute to the sensor-pore coupling. We propose three specific aims to examine three key aspects of this hypothesis: 1) the VSD-PGD interactions in VSD-pore coupling, 2) the VSD-CTD interactions in both VSD-pore and Ca2+- pore couplings, and 3) the role of a peptide linker between PGD and CTD in both the VSD-pore and Ca2+-pore couplings. We will use novel structure based screening methods to identify compounds that modulate channel function. These compounds and mutations in the channel protein will serve as probes to indicate the structural motifs that are key to the sensor-pore coupling in BK channels. Threading the biophysics of mutations and modulators onto the channel structures will allow us to understand the molecular mechanisms of how physiological stimuli open BK channels. The results of these studies will identify novel binding sites, chemical cores and new mechanisms of altering channel function by drugs, which will directly help drug development targeting BK channels. Our studies on BK channels may provide insights for the understanding of other ion channels that share similar structural and functional characteristics.