Structural Studies on Prokaryotic Potassium Channels

描述（由申请方提供）：离子通道有助于产生膜电位、受体电位和动作电位。它们是神经科学中许多细胞的基本特征：兴奋性的分子构建块。这些蛋白质涉及所有可兴奋组织的生理学和病理生理学，是许多疾病过程（包括癫痫和心律失常）的基础，并且是临床医学中使用的基本药物的主要靶标。钾通道是结构上相关的离子通道的大超家族的系统发育创始者，所述超家族包括核苷酸门控通道、钠通道和钙通道。钾通道通常由四个相同的亚基以四重对称的方式组装而成。这种相当简单的结构蓝图和只有一种亚基类型的实质性实用优势使钾通道成为一个研究较多的模型系统。钾通道有两个重要的特性：它们选择性地接纳钾而不是钠，并且它们在功能过程中改变其结构，称为门控。该提案探讨了钾通道中的门控转换。我们将使用半胱氨酸扫描诱变，定点自旋标记，定点质量标记，X射线晶体学和电生理学的组合来研究三个原核钾通道的门控转换：KcsA，MthK和KvAP。 这项提案的长期目标是在结构水平上了解离子通道的功能特性。

DESCRIPTION (provided by applicant): Ion channels are instrumental in the generation of membrane potential, receptor potential, and action potential. They are the molecular building blocks for what is an essential characteristic of many cells in neuroscience: excitability. These proteins are implicated in the physiology and pathophysiology of all excitable tissues, underlie many disease processes including epilepsies and arrhythmias, and are major targets of essential drugs used in clinical medicine. Potassium channels are the phylogenetic founders of a large superfamily of structurally related ion channels that includes nucleotide gated channels, sodium channels, and calcium channels. Potassium channels are typically assembled from four identical subunits in a four-fold symmetrical fashion. This rather simple structural blueprint and the substantial practical advantage of only one subunit type have made potassium channels a much studied model system. Potassium channels exhibit two important properties: they selectively admit potassium over sodium and they change their structure during function in a process called gating. This proposal explores the gating transition in potassium channels. We will use a combination of cysteine scanning mutagenesis, site-directed spin labeling, site-directed mass tagging, X-ray crystallography, and electrophysiology to study the gating transition in three prokaryotic potassium channels: KcsA, MthK, and KvAP. The long term goal of this proposal is to understand functional properties of ion channels at a structural level.