Making Sense of Voltage Sensors

描述（由申请人提供）：电压门控通道是包含三个关键结构元素的膜蛋白：离子传导孔域（PD），可以区分K+， Na+和Ca2+离子；PD内的栅极，使闭合状态下的离子流动最小化；以及电压感应域（VSD），检测膜电压的变化并触发栅极的开启和关闭。一个基本的实验问题是很难通过晶体学捕获膜中vsd的关键原子细节。该项目（Stephen White，主任）旨在通过协同使用特定氘化、中子衍射、中子反射率和分子动力学模拟，获得流体脂质双层中vsd的关键结构信息。该方案由六个紧密相连的项目和一个重要的合作组成：核心A.行政核心。斯蒂芬·怀特，PI。该核心为整个项目提供行政支持。核心B.中子散射核心。斯蒂芬·怀特，PI。中子核心为将在NIST中子研究中心进行的中子衍射/反射率测量提供技术和培训支持。核心c有机合成核心，理查德·钱伯林，PI。有机合成核心将提供新的特殊氘化化合物，如脂类和氨基酸，并将进行vsd和通道的半合成。它将设在加州大学欧文分校。项目1：通道和电压传感器域的分子动力学模拟。道格拉斯·托比亚斯，PI。这个项目位于加州大学欧文分校，致力于MD模拟，这是项目2和项目3中大多数实验工作的基础和灵感。项目2。脂质双层中电压传感器分子的中子衍射研究。斯蒂芬·怀特，PI。实验旨在了解双层中KvAP VSD的相互作用，KvAP S4螺旋与多层双层中脂质的相互作用，以及双层中VSD阻断毒素VSTxl毒素的处置。项目3。跨膜电化学电位对电压门控钾通道结构影响的研究。J.肯特·布莱西，私家侦探。该项目位于宾夕法尼亚大学，旨在将vsd和整个钾通道整合到单个系链脂质双分子层中，并通过时间分辨x射线反射率和中子反射率观察跨膜电化学电位诱导的传感器和通道的结构变化。协作。钾通道生物物理学。肯顿·斯沃茨，PI。斯沃茨博士在国家科学研究院的实验室有一个很有影响力的研究项目，专门研究电压门控离子通道的机制。他的工作直接集中在电压传感器结构域的分子基础及其与vsd阻断毒素的相互作用。

DESCRIPTION (provided by applicant): Voltage-gated channels are membrane proteins that contain three crucial structural elements: an ion conduction pore domain (PD) that can distinguish K+ from Na+ and Ca2+ ions; a gate within the PD that minimizes the flow of ions in the closed state; and voltage-sensing domains (VSD) that detect changes in membrane voltage and trigger opening and closing of the gate. A fundamental experimental problem is the difficulty of capturing critical atomic details of VSDs in membranes by crystallography. This program project (Stephen White, Director) is designed to obtain critical structural information about VSDs in fluid lipid bilayers through the concerted use of specific deuteration, neutron diffraction, neutron reflectivity, and molecular dynamics simulations. The Program consists of six closely interlocked Projects and an important collaboration: Core A. Administrative Core. Stephen White, PI. This core provides administrative support for the entire Program. Core B. Neutron Scattering Core. Stephen White, PI. The neutron Core provides technical and training support for neutron diffraction/reflectivity measurements that will be carried out at the NIST Center for Neutron Research. Core C. Organic Synthesis Core, Richard Chamberlin, PI. The Organic Synthesis Core will provide novel specifically deuterated compounds, such as lipids and amino acids, and will carry out semi-syntheses of VSDs and channels. It will be located at UC Irvine. Project 1 Molecular Dynamics Simulations of Channels and Voltage Sensor Domains. Douglas Tobias, PI. Located at UC Irvine, this project is devoted to MD simulations that underlie-and inspire-most of the experimental work in projects 2 and 3. Project 2. Neutron Diffraction Studies of Voltage Sensor Molecules in Lipid Bilayers. Stephen White, PI. The experiments are directed toward a structural understanding of the interactions of the KvAP VSD in bilayers, the interaction of the KvAP S4 helix with lipids in multilamellar bilayers, and the disposition of the VSD-blocking toxin VSTxl toxin in bilayers. Project 3. Structural Studies of Voltage-Gated Potassium Channels as a Function of Transmembrane Electrochemical Potential. J. Kent Blasie, PI. Located at the University of Pennsylvania, this project is directed toward incorporating VSDs and whole potassium channels into single, tethered lipid bilayers and to observe by time-resolved x-ray reflectivity and neutron reflectivity structural changes in the sensors and channels induced by transmembrane electrochemical potentials. Collaboration. Potassium Channel Biophysics. Kenton Swartz, PI. Dr. Swartz's laboratory at the NINDS has an influential research program devoted to the mechanism of voltage gated ion channels. His work focuses directly on the molecular basis of voltage sensor domains and their interactions with VSD-blocking toxins.