Structural basis of nicotinic acetylcholine receptor gating and toxin inhibition

烟碱型乙酰胆碱受体是治疗神经退行性疾病、成瘾和精神疾病的靶点 生病了。这些五聚体配基门控离子通道是Cys-loop受体的典型成员 超级家族，在中枢和外周神经系统中调节快速的神经传递。 关于尼古丁受体生物物理学和药理学的基本问题仍然存在，这在很大程度上是由于 有限的高分辨率构造信息。我们建议确定两个分子的高分辨率结构 用单粒子冷冻电子显微镜研究原型烟碱受体亚型 基于分子动力学模拟和电生理学的机械假说。我们的第一个目标是 肌型烟碱受体，五聚体受体超家族的创始成员。基因突变 该通道以及针对该受体的自身免疫抗体会导致肌无力综合征。我们的第二个 靶点是人的α7尼古丁受体。在尼古丁受体中，α7在几个方面都是例外的：它 在生理上作为同戊异构体组装，它在大脑中大量表达，但也在非 电可兴奋的细胞类型，它对钙离子有很高的渗透性，并且在微秒内就会脱敏。这个 受体是神经退行性疾病、成瘾和炎症的靶点。我们建议使用单人 粒子低温电子显微镜结合诱变、电生理学和分子动力学 模拟阐明通道激活、配基识别和离子渗透的机制 明确的烟碱受体亚型，以定义一般机制和特殊属性。

Nicotinic acetylcholine receptors are therapeutic targets for neurodegenerative disorders, addiction, and mental illness. These pentameric ligand-gated ion channels are prototypical members of the Cys-loop receptor superfamily, which mediate fast neurotransmission throughout the central and peripheral nervous systems. Fundamental questions about nicotinic receptor biophysics and pharmacology remain, due in large part to the limited high-resolution structural information. We propose to determine high-resolution structures of two archetypal nicotinic receptor subtypes using single particle cryo-electron microscopy and investigate structure- based mechanistic hypotheses using molecular dynamics simulations and electrophysiology. Our first target is the muscle-type nicotinic receptor, the founding member of the pentameric receptor superfamily. Mutations in the channel, as well as autoimmune antibodies to the receptor, cause myasthenic syndromes. Our second target is the human α7 nicotinic receptor. α7 is exceptional among nicotinic receptors in several ways: it assembles physiologically as a homopentamer, it is expressed abundantly in the brain but also in non- electrically excitable cell types, it has a high permeability to Ca2+, and it desensitizes in microseconds. The receptor is a target in neurodegenerative disease, addiction and inflammation. We propose to use single particle cryo-electron microscopy combined with mutagenesis, electrophysiology and molecular dynamics simulations to elucidate mechanisms of channel activation, ligand recognition and ion permeation in these two distinctinctive nicotinic receptor subtypes to define general mechanisms and idiosyncratic properties.