Molecular biology of viral capsids

描述(申请人提供)：病毒衣壳蛋白是病毒过程的重要调节者，从翻译到RNA复制，到RNA包装，以及细胞天然免疫反应的调节。在含有被包装成单独的病毒粒子的分段基因组的病毒中，衣壳蛋白必须协调每个RNA的活动。该项目的总体目标是更好地了解RNA病毒感染的早期步骤。也就是说，衣壳是如何与病毒粒子内的病毒RNA相互作用并促进进入细胞的？雀麦花叶病毒(BMV)将是本研究的模型病毒。BMV是一种无包膜的节段性正链RNA病毒，在顺式和反式作用因子、复制酶复合体的形成以及病毒依赖RNA合成的机制等方面做出了显著贡献。初步结果表明，BMV衣壳的一个富含精氨酸的基序有助于选择性地包裹BMV RNA，并作为细胞穿透信号。后一组观察结果导致了一种假设，即植物病毒通过蛋白质转导机制进入细胞。该项目包含两个目标，第一个目标是通过结合冷冻电子显微镜和单颗粒重建、RNA构象和RNA-衣壳相互作用的生化图谱以及相互作用如何影响感染过程的分子遗传学分析来了解病毒粒子的结构。第二个目的是利用荧光标记的多肽和病毒、共聚焦显微镜和电子显微镜来阐明细胞穿透肽和病毒衣壳进入细胞的机制。这项工作将有助于更好地理解病毒感染过程。 与公共卫生相关：病毒衣壳蛋白在病毒感染过程中有许多重要的作用，从调节翻译到保护病毒基因组免受细胞天然免疫检测。这一建议包含一套全面的实验，以研究感染植物的RNA病毒的衣壳蛋白如何与病毒RNA相互作用，在包裹过程中重新配置RNA的形状，并介导进入细胞。从拟议的研究中获得的信息将有助于对病毒结构、蛋白质-RNA相互作用以及病毒如何进入细胞的新见解。

DESCRIPTION (provided by applicant): Viral capsid proteins are important regulators of viral processes from translation, to RNA replication, to RNA packaging, and the modulation of cellular innate immune responses. In viruses with segmented genomes that are packaged into separate virions, the capsid protein must coordinate the activities for each of the RNAs. The overall goal of this project is to better understand the early steps in an RNA virus infection. That is, how does the capsid interact with the viral RNAs within the virion and facilitate entry into cells? Brome mosaic virus (BMV) will be the model virus for this study. BMV is a nonenveloped segmented positive-strand RNA virus that has served as a model system with notable contributions to the cis- and trans-acting factors, the formation of the replicase complex, and the mechanism of viral RNA-dependent RNA synthesis. Preliminary results showed that an arginine-rich motif of the BMV capsid contributes to the selective encapsidation of BMV RNAs and acts as a cell-penetration signal. The latter set of observations led to the hypothesis that plant viruses gain entry into cells through a protein transduction mechanism. This project contains two aims, the first will seek to understand the architecture of the virion through a combination of cryoelectron microscopy and single particle reconstruction, biochemical mapping of RNA conformation and RNA-capsid interaction, and a molecular genetic analysis of how the interactions will influence the infection process. The second aim seeks to elucidate the mechanism of cell entry of the cell-penetration peptides and the viral capsid using fluorescently-labeled peptides and viruses, confocal microscopy and electron microscopy. The work will lead to improved understanding of the viral infection process. PUBLIC HEALTH RELEVANCE: Viral capsid proteins have many essential roles during a virus infection, from the regulation of translation to the protection of the viral genome against cellular innate immune detection. This proposal contains a comprehensive set of experiments to examine how the capsid protein of a plant-infecting RNA virus interacts with the viral RNA, reconfigures the shape of the RNA during encapsidation, and mediates entry into cells. The information gained from the proposed studies will contribute new insights to virus architecture, protein-RNA interactions, and how viruses gain entry into the cell.