Structural Foundations of Nicotinic Acetylcholine Receptor Function

项目摘要 在整个神经系统中，烟碱乙酰胆碱受体（nAChR）的任务是促进快速的神经传导。 通过将化学信号转换为电脉冲来实现细胞之间的通信。当乙酰胆碱 当nAChR释放到突触中时，膜结合的nAChR结合小的有机分子并打开受体 孔响应，允许细胞外离子的选定子集流入细胞。破坏正常 nAChR功能可导致严重和衰弱的神经系统疾病，如肌无力综合征 和某些癫痫病我们实验室的一个主要重点是揭示三维 nAChR的结构允许它们执行其生理任务。因为我们断言， 受体结构如何赋予功能将使我们能够更有效地干预nAChR的设置， 神经系统疾病。最近确定的高分辨率nAChR结构揭示了一个保守的 孔衬和外围α-螺旋之间的电荷-电荷相互作用，在第一次实验中并不明显。 发表的nAChR结构。该建议试图通过以下方式确定这种保守相互作用的功能： 将受体结构的精确修饰与最先进的单通道电生理学相结合。我 初步工作表明，这种跨膜电荷-电荷相互作用对细胞的稳定性至关重要。 受体的开放状态和nAChR固有的均匀开放通道电流。所以我 假设孔隙内衬和外围之间普遍保守电荷-电荷相互作用 跨膜α-螺旋增强门控效率并促进nAChR中的均匀离子渗透。测试 这一假设我将打破孔周边电荷电荷相互作用使用诱变和探测 使用单通道电生理学检测所得受体的功能。首先，我将确定离子渗透 突变体和野生型受体的特征（aim 1）。然后我会确定怀尔德的门控能量 型和突变型受体（AIM 2）。实现这两个目标将有助于提供一个机制框架 需要了解和治疗由异常nAChR功能驱动的疾病。

Project Summary Throughout the nervous system, nicotinic acetylcholine receptors (nAChRs) are tasked with facilitating rapid communication between cells by converting a chemical signal to an electrical impulse. When acetylcholine is released into the synapse, membrane bound nAChRs bind the small organic molecule and open the receptor pore in response, allowing a selected subset of extracellular ions to flow into the cell. Disruption of normal nAChR function can result in severe and debilitating neurological diseases, such as myasthenic syndromes and certain epileptic disorders. A major emphasis of our laboratory is uncovering how the three dimensional structure of nAChRs allows them to perform their physiologic task. For we assert that a basic understanding of how receptor structure endows function will allow us to more effectively intervene in the setting of nAChR- driven neurological diseases. Recently determined high-resolution nAChR structures reveal a conserved charge-charge interaction between pore-lining and peripheral α-helices that was not apparent in the first published nAChR structures. This proposal seeks to determine the function of this conserved interaction by pairing precise modifications to receptor structure with state-of-the-art single channel electrophysiology. My preliminary work shows that this transmembrane charge-charge interaction is critical for the stability of the open state of the receptor and for the uniform open channel current inherent to nAChRs. Therefore I hypothesize that a universally conserved charge-charge interaction between pore-lining and peripheral transmembrane a-helices enhances gating efficiency and facilitates uniform ion permeation in nAChRs. To test this hypothesis I will break the pore-peripheral charge-charge interaction using mutagenesis and probe the function of resultant receptors using single channel electrophysiology. First, I will determine the ion permeation characteristics of the mutant and wild-type receptors (aim 1). Then I will determine the gating energetics of wild type and mutant receptors (aim 2). Accomplishing these two aims will help provide the mechanistic framework required to understand and treat diseases driven by abnormal nAChR function.