VOLTAGE-GATING MECHANISM OF POTASSIUM CHANNELS

钾通道的电压门控机制

基本信息

批准号：
7955620
负责人：
FATEMEH KHALILI-ARAGHI
金额：
$ 3.83万
依托单位：
UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-08-01 至 2010-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7955620
关键词：
Agreement Animals Architecture Arginine Ataxia Bioinformatics Cardiac Cardiovascular Diseases Cations Cell membrane Cells Charge Chimera organism Collaborations Computer Retrieval of Information on Scientific Projects Database Coupled Environment Family Funding Grant Human Institution Insulin Integral Membrane Protein Ion Channel Ions Life Lipid Bilayers Medical Membrane Modeling Molecular Molecular Conformation Movement Muscle Cells Nervous system structure Neurologic Neurons Philadelphia Play Positioning Attribute Potassium Potassium Channel Proteins Regulation Research Research Personnel Resolution Resources Rest Role Science Signal Transduction Simulate Sodium Channel Source Staging Structural Models Structure System Transmembrane Domain United States National Institutes of Health Water Work electric field electrical potential member programs response sensor simulation voltage

项目摘要

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Voltage-gated potassium (Kv) channels (http://www.ks.uiuc.edu/Research/kvchannel/)are integral membrane proteins present in all three domains of life. In a specializedclass of animal cell, known as excitable cells - including neurons, muscle cells, andendocrine cells - Kv channels work with other cation channels (sodium and calciumchannels) to regulate the electrical activity and signaling of the cell [1]. Kv channelsactivate (open and close) in response to changes in the electrical potential acrossthe cell membrane allowing passive and selective conduction of K+ ions through thechannel. Potassium conduction is directed by the electrochemical gradient acrossthe cell membrane and can achieve very high rates, while still discriminating againstall other cations (including the smaller Na+ ions) [1]. In addition to electrical signalingin nervous systems, Kv channels play an important role in the regulationof cardiac excitability and regulation of insulin release. In humans, malfunction ofthese channels can result in neurological or cardiovascular diseases such as long QTsyndrome or episodic ataxia [2].The crystal structures of Kv1.2 [3, 4], a member of the Shaker K+ channel family,have provided the first view of the molecular architecture of a mammalian potassiumchannel in a putative open state at 3.9 ¿A resolution. However, the structure of thechannel in the closed state is still unknown.In collaboration with the Yarov-Yarovoy and Roux labs, the Resource has developedan atomic model for the closed state of the channel. The initial model was generatedusing the structure prediction program ROSETTA [5, 6]. The open and closedstate models of the channel [7] were refined in several stages of molecular dynamicssimulation. Each model was simulated in explicit water/membrane environment inthe presence of an electric field. A total of 400ns of simulations were required toobtain stable conformations of the channel, for the systems containing 100,000 or350,000 atoms.To study the gating mechanism of Kv1.2, the gating charge that is transferredacross the membrane upon activation of the channel is calculated from 900 ns ofall-atom MD simulation of the two protein states. The contribution of individualcharged residues of the channel to the total gating charge is determined, showingthat positions of four conserved arginines within the transmembrane region aretightly coupled to the membrane voltage, and that their movement drives the transitionof the channel between the two states. The results are in agreement withexperimental values obtained for the gating charge [8, 9], indicating that the refinedmodels of Kv1.2 are representatives of the two functional states of Kv channels.BIBLIOGRAPHY[1] B. Hille. Ionic channels of excitable membranes. Sinauer Associates, Sunderland,MA, 2nd edition, 1992.[2] G. J. Siegal, B. W. Agranoff, R. W. Albers, S. K. Fisher, and M. D. Uhler. Basicneurochemistry, molecular, cellular, and medical aspects. Lippincott Williams andWilkins, Philadelphia, 6th edition, 1999.[3] S. B. Long, E. B. Campbell, and R. MacKinnon. Crystal structure of a mammalianvoltage-dependent Shaker family K+ channel. Science, 309:897903, 2005.[4] X. Tao and R. MacKinnon. Functional analysis of Kv1.2 and paddle chimera kvchannels in planar lipid bilayers. J. Mol. Biol., 382:2433, 2008.[5] P. Bradley, K. M. S. Misura, and D. Baker. Toward high-resolution de novo structureprediction for small proteins. Science, 309:18681871, 2005.[6] V. Yarov-Yarovoy, D. Baker, and W. A. Catterall. Voltage sensor conformations inthe open and closed states in ROSETTA structural models of K+ channels. Proc.Natl. Acad. Sci. USA, 103:72927297, 2006.[7] M. M. Pathak, V. Yarov-Yarovoy, G. Agrawal, B. Roux, P. Barth, S. Kohout,F. Tombola, and E. Y. Isacoff. Closing in on the resting state of the Shaker K+channel. Neuron, 56:124140, 2007.[8] S. Seoh, D. Sigg, D. M. Papazian, and F. Bezanilla. Voltage-sensing residues in theS2 and S4 segments of the Shaker K+ channel. Neuron, 16:11591167, 1996.[9] S. K. Aggarwal and R. MacKinnon. Contribution of the S4 segment to the gatingcharge in the Shaker K+ channel. Neuron, 16:11691177, 1996.

该子项目是利用该技术的众多研究子项目之一资源由 NIH/NCRR 资助的中心拨款提供。研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金，因此可以出现在其他 CRISP 条目中列出的机构是。中心，不一定是研究者的机构。电压门控钾 (Kv) 通道 (http://www.ks.uiuc.edu/Research/kvchannel/) 是存在于生命所有三个领域的完整膜蛋白，存在于一类特殊的动物细胞中，称为可兴奋细胞。 - 包括神经元、肌肉细胞和内分泌细胞 - Kv 通道与其他阳离子通道（钠和钙通道）一起调节细胞的电活动和信号传导 [1]，以响应细胞的变化。跨细胞膜的电位允许 K+ 离子通过通道进行被动和选择性传导。钾离子传导是由跨细胞膜的电化学梯度引导的，并且可以实现非常高的速率，同时仍能区分所有其他阳离子（包括较小的 Na+）。除了神经系统中的电信号传导之外，Kv 通道在人类的心脏兴奋性和胰岛素释放调节中也发挥着重要作用，这些通道的功能障碍可能导致神经或心血管疾病，例如长时间。 QT 综合征或阵发性共济失调 [2]。Shaker K+ 通道家族成员 Kv1.2 [3, 4] 的晶体结构首次提供了哺乳动物钾通道处于假定开放状态的分子结构视图。 3.9 ¿然而，关闭状态下的通道结构仍然未知。Resource 与 Yarov-Yarovoy 和 Roux 实验室合作，开发了通道关闭状态的原子模型，并使用该结构生成了初始模型。预测程序 ROSETTA [5, 6]。通道的开放和关闭状态模型 [7] 在分子动力学模拟的几个阶段中进行了模拟，并在存在电场的情况下进行。全部的对于包含 100,000 或 350,000 个原子的系统，需要 400ns 的模拟才能获得通道的稳定构象。为了研究 Kv1.2 的门控机制，在通道激活时跨膜转移的门控电荷计算为 900确定了两种蛋白质状态的 ns 全原子 MD 模拟，通道的各个带电残基对总门控电荷的贡献，显示了的位置。跨膜区域内的四个保守的精氨酸与膜电压紧密耦合，它们的运动驱动通道在两种状态之间的转变，结果与门控电荷的实验值一致[8, 9]。 Kv1.2 的精制模型代表了 Kv 通道的两种功能状态。参考书目 [1] B. Hille 的可兴奋膜离子通道。马萨诸塞州桑德兰，第 2 版，1992 年。[2] G. J. Siegal、B. W. Agranoff、R. W. Albers、S. K. Fisher 和 M. D. Uhler。基础神经化学、分子、细胞和医学方面，费城，第 6 版。 3] S. B. Long、E. B. Campbell 和 R. MacKinnon。哺乳动物电压依赖性 Shaker 家族 K+ 通道的晶体结构，科学，309:897 903, 2005。[4] X. Tai 和 R. MacKinnon。平面脂质双层中 Kv1.2 和桨嵌合体 kv 通道的功能分析。生物学，382：24 33，2008。[5] Misura 和 D. Baker。《科学》杂志，309：1868 1871，2005 年。[6] V. Yarov-Yarovoy、D. Baker 和 W. A. Catterall。美国国家科学院院刊 ROSETTA 结构模型。 103:7292 7297, 2006。[7] M. M. Pathak、V. Yarov-Yarovoy、G. Agrawal、B. Roux、P. Barth、S. Kohout、F. Tombola 和 E. Y. Isacoff。摇床 K+ 神经元，56:124 140，2007 年。[8] S. Seoh、D. Sigg、D. M. Papazian 和 F. Bezanilla。Shaker K+ 通道 S2 和 S4 片段中的电压感应残基，16:1159 1167，1996。[9] S. K. Aggarwal 和 R. MacKinnon。 S4 段对 Shaker K+ 通道中的门控电荷的贡献。 16：1169 1177，1996 年。