Structural mechanism of K channel modulation by cellular redox state

细胞氧化还原态调节 K 通道的结构机制

• 批准号: 7841391
• 负责人: Ming Zhou
• 金额: $ 33.33万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7841391
• 关键词: Architecture; Binding; Catalysis; Cell membrane; Cells; Communication; Complex; Coupled; Coupling; Diffuse; Family; Goals; Heart; Hormones; Hypoxia; Integral Membrane Protein; Membrane; Membrane Potentials; Molecular; Molecular Conformation; NADP; Neurons; Oxidation-Reduction; Oxidative Stress; Oxidoreductase; Physiological Processes; Physiology; Potassium Channel; Proteins; Reagent; Research Personnel; Resolution; Rest; Side; Structure; Testing; Therapeutic; X-Ray Crystallography; base; cofactor; macromolecule; member; potassium ion; programs; response; therapeutic development; voltage

Voltage-dependent potassium channels (Kv) are integral membrane proteins that, in response to membrane voltage changes, catalyze potassium ions to diffuse across the cell membrane. Kv channels regulate membrane excitability and are essential to many physiological processes such as the rhythmic beating of heart, the communication between neurons, and the secretion of hormones. The beta subunit (Kvp) of the Shaker type Kv channels (Kv1) permanently attaches to the intracellular side of a channel and is implicated in channel modulation during oxidative stresses and hypoxic conditions. Sequence conservation suggests that Kvp resembles an aldo-keto reductase (AKR), and the crystal structure of a Kvp showed that it has a canonical AKR fold, a tightly bound cofactor nicotinamide adenine dinucleotide phosphate (NADPH), and highly conserved catalytic residues in the right geometry for catalysis to happen. However, the enzymatic activity of Kvp has never been demonstrated. The overall objectives of this proposal are to examine how Kvp as a functional AKR modulates channel function, to investigate how the enzymatic activity is coupled to channel activities, and to develop an atomic level understanding of the coupling mechanism. The long-term goals of the project are to understand the physiology of Kvp, and the principles governing Kv channel modulations. We have recently identified several Kvp substrates, and demonstrated that Kvp is a functional aldo-keto reductase. We also found that the substrates modulates channel function only when a Kvp is co- expressed. These exciting new results led us to hypothesize that: 1) the AKR function of Kvp is coupled to Kv channel functions; 2) the coupling is achieved through interactions between intracellular domains and Kvp 3) different redox states of Kvp have different conformations that induce a conformational change of a channel domain. To test these hypotheses, we propose the following three specific aims: Aim 1: To examine the functional coupling between channel activities and the AKR activity of Kvp. Aim 2: To investigate the molecular bases of the coupling mechanism. Aim 3: To investigate the structural bases of the coupling. Results from this project will help us understand modulations of the various Kv channel families, and will help develop therapeutic reagents that target the macromolecule complex.

电压依赖性钾通道（Kv）是一种膜蛋白， 电压变化，催化钾离子扩散穿过细胞膜。Kv通道调节 膜的兴奋性，是必不可少的许多生理过程，如有节奏的跳动， 心脏，神经元之间的交流，以及激素的分泌。β亚单位（Kvp）的 振荡器型Kv通道（Kv 1）永久附着在通道的细胞内侧，并与细胞内的细胞内信号传导有关。 在氧化应激和缺氧条件下的通道调节中。序列保守性表明 Kvp类似于醛酮还原酶（AKR），Kvp的晶体结构表明它具有 典型AKR折叠，紧密结合的辅因子烟酰胺腺嘌呤二核苷酸磷酸（NADPH），和 高度保守的催化残基在正确的几何结构中催化作用的发生。然而，酶 KVP的活性从未得到证实。本提案的总体目标是研究KVP如何 作为功能性AKR调节通道功能，研究酶活性如何与 通道活动，并开发一个原子级的耦合机制的理解。长期 该项目的目标是了解Kvp的生理学，以及Kv通道的原理 调制我们最近鉴定了几种Kvp底物，并证明Kvp是一种功能性的 醛酮还原酶我们还发现，只有当Kvp是共同的时，底物才能调节通道功能。 表达。这些令人兴奋的新结果使我们假设：1）Kvp的AKR功能与 Kv通道功能; 2）通过胞内结构域与Kvp之间的相互作用实现偶联 3)Kvp的不同氧化还原态具有不同的构象，其诱导了一种 信道域为了验证这些假设，我们提出了以下三个具体目标： 目的1：研究Kvp的AKR活性与通道活性之间的功能耦合。 目的2：探讨偶联机理的分子基础. 目的3：研究耦合的结构基础。 该项目的结果将有助于我们了解各种KV通道家族的调制，并将有助于 开发靶向大分子复合物的治疗试剂。