CONFORMATIONAL DYNAMICS OF ICOSAHEDRAL VIRUSES PROBED BY SAXS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 许多病毒的蛋白质衣壳对环境信号做出动态反应，如DNA或RNA包装、受体结合以及pH或离子组成的变化。结果，它们经历了构象变化，涉及数百个蛋白质亚基和核酸的协同重组。小角X射线散射(SAXS)非常适合于监测溶液中的这些结构变化。我们建议使用SAXS来监测在两种二十面体病毒颗粒中观察到的动态构象变化：1)由420个相同亚基组成的空噬菌体头部衣壳(HK97噬菌体)；2)由240个相同衣壳蛋白和包膜RNA组成的单链RNA昆虫病毒(N-omega-V四病毒)。我们获得的数据将用于生成低分辨率的3D重建，以及使用奇异值分解(SVD)对时间分辨的结构变化进行定量分析。所提出的研究的主要智力目标是在这些大规模和复杂的组装的大规模构象变化中测量亚基之间的协同程度，并探索动力学和平衡中间态的存在。通过定量解决这些问题，我们希望更好地了解病毒的功能，并启发未来以抗病毒化合物和中和抗体为靶点的衣壳蛋白的策略。

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. The protein capsids of many viruses respond dynamically to environmental signals such as DNA or RNA packaging, receptor binding, and changes in pH or ionic composition. As a result, they undergo conformational changes that involve the concerted reorganization of hundreds of protein subunits and nucleic acid. Small-angle x-ray scattering (SAXS) is ideally suited to monitoring these structural changes in solution. We propose to use SAXS to monitor the dynamic conformational changes observed in two types of icosahedral virus particles, 1) an empty phage head capsid composed of 420 identical subunits (HK97 bacteriophage) and 2) a ssRNA insect virus composed of 240 identical capsid proteins and encapsidated RNA (N-omega-V tetravirus). The data we obtain will be used for generating low-resolution 3D reconstructions as well as for quantitative analysis of time-resolved structural changes using Singular Value Decomposition (SVD). The primary intellectual goals of the proposed studies are to measure the extent of cooperativity among subunits during large-scale conformational changes of these massive and complex assemblies, and to probe for the existence of kinetic and equilibrium intermediate states. By quantitatively addressing these issues we hope to better understand virus function and to enlighten future strategies for targeting capsids with antiviral compounds and neutralizing antibodies.