How Do Genome and Capsid Fluctuations Determine the Translation Efficiencies of RNA Viruses?

许多病毒，包括动物和植物病原体，具有非常简单的基因组和生命周期，但人们对它们的基因在感染宿主后如何开始工作知之甚少。本项目研究由单个RNA分子包裹在蛋白的球形外壳（衣壳）内构成的植物病毒，并将采用分子生物学和物理学的方法和技术对该病毒进行研究。要回答的主要问题是病毒基因组（由RNA而不是DNA组成）是如何从细胞内的衣壳中被拉出来的。目前，加州大学洛杉矶分校与历史上的黑人学院和大学（HBCU）、加州州立大学多明格斯山分校（其70%的人口为少数族裔）和中国（通过加州大学洛杉矶分校的跨学科科学技术学生（CSST）项目）之间的项目将使不同的本科生在未来三个夏天参与研究。这项研究的科学目标集中在基因组直接转化为感染细胞细胞质中蛋白质产物的病毒，而不是基因组涉及DNA复制和转录的更复杂的病毒，因此需要进入宿主细胞的细胞核。在这项工作中测试的一个特殊假设是，病毒基因组可以与核糖体机制结合，并在保护它的衣壳保持完整的情况下表达其基因。当基因组从完整的衣壳中波动并启动其基因表达（转化为蛋白质产物）时，将使用几种单病毒颗粒方法试图捕捉基因组的末端。最先进的物理技术，包括高分辨率低温电子显微镜结构测定，以及能够分别操纵病毒基因组和衣壳的光学和磁性“镊子”，将在整个项目中得到利用。

Many viruses, including animal and plant pathogens, have very simple genomes and life cycles, and yet little is known about how their genes start working once they have infected their host. This project studies plant virus made of a single RNA molecule packaged inside a spherical shell of protein (capsid), and this virus will be investigated using methods and techniques of molecular biology and physics. The main question that will be answered is how virus genome (which is made of RNA instead of DNA) is pulled out of the capsid inside the cell. Programs currently in place between UCLA and Historically Black Colleges and Universities (HBCU), California State University Dominguez Hills (with its 70% population of under-represented minorities), and China (through UCLA's Cross-disciplinary Students in Science and Technology [CSST] program) will enable the participation of diverse undergraduate students in research during the next three summers. The scientific aims of this research are focused on viruses whose genomes are directly translated into protein products in the cytoplasm of infected cells, as opposed to more complicated viruses whose genomes involve DNA replication and transcription and hence need to enter the nucleus of their host cells. The particular hypothesis being tested in this work is the possibility that the viral genome can engage with the ribosomal machinery and have its genes expressed even as the capsid protecting it remains intact. Several single-virus-particle methods will be used in attempts to catch an end of the genome as it fluctuates out of the intact capsid and initiates its gene expression (translation into protein products). State-of-the-art physical techniques, including high-resolution cryoelectron microscopy structure determination, and optical and magnetic "tweezers" capable of manipulating separately both the viral genome and its capsid, will be exploited throughout the project.