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件的膜蛋白：可以区分K+与Na+和Ca 2+离子的离子传导孔结构域（PD）; PD内的门，其在关闭状态下最小化离子流;以及检测膜电压变化并触发门的打开和关闭的电压感应结构域（VSD）。一个基本的实验问题是通过结晶学捕获膜中VSD的关键原子细节的困难。该计划项目（斯蒂芬白色，主任）的目的是通过特定的氘，中子衍射，中子反射率和分子动力学模拟的协调使用，以获得关键的结构信息VSD在流体脂质双层。该计划包括六个密切相关的项目和一个重要的合作：核心A。行政核心。斯蒂芬白色，PI。该核心为整个方案提供行政支助。核心B。中子散射核心。斯蒂芬白色，PI。中子堆芯为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·张伯伦，PI。有机合成核心将提供新的特定氘代化合物，如脂质和氨基酸，并将进行VSD和通道的半合成。它将位于UC Irvine。项目1通道和电压传感器结构域的分子动力学模拟。道格拉斯托拜厄斯，PI。位于加州大学欧文分校，该项目致力于MD模拟，支持并激发了项目2和3中的大部分实验工作。项目2.脂质双层膜中电压传感分子的中子衍射研究。斯蒂芬白色，PI。该实验是针对结构的理解KvAP VSD的双层中的相互作用，KvAP S4螺旋与脂质在多层双层中的相互作用，和VSD阻断毒素VSTxl毒素在双层中的处置。项目3。跨膜电化学电位对电压门控钾通道结构的影响。J.肯特·布雷西，PI。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拴系的脂质双层中，并通过时间分辨的X射线反射率和中子反射率观察跨膜电化学电位引起的传感器和通道的结构变化。协作钾通道生物物理学。P.S. Swartz，PI。Swartz博士在NINDS的实验室有一个有影响力的研究项目，致力于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.