Plant virus interactions with insect viruses

我们建议利用这个计划项目赠款作为一个机会来探索一系列不同的重要生物学问题。这些主题与PPG的合作主题非常契合，并将使我的实验室能够探索结构病毒学的几个新的、重要的途径。这笔赠款的一个主要主题是使用结构生物学方法来研究植物病毒传播媒介所涉及的过程。利用黄瓜花叶病毒(CMV)作为通过没有辅助蛋白的蚜虫传播的病毒的模型，我们计划研究与蚜虫口器相互作用的结构基序，这是蚜虫传播所必需的。初步工作已经确定了蚜虫传播的表面残留物。我们建议扩展当前CMV模型的分辨率。这一技术与免疫学和低温电子显微镜技术相结合，将可以用来研究蚜虫和病毒之间的相互作用。对于POTY病毒，一种辅助蛋白HC-Pro需要通过蚜虫传播。HC-Pro的N-末端结构域富含半胱氨酸，负责媒介传播和在植物中的系统传播。作为了解植物病毒传播的第三种方法，我们正在进行对豆荚斑驳病毒(CPMoV)的结构研究。我们已经确定了CPMoV的低分辨率(约23埃)结构，其衣壳组织与番茄丛矮病毒(TBSV)的另一成员非常相似。然而，与TBSV不同的是，CPMoV对核糖核酸酶不敏感--核糖核酸酶被认为是甲虫传播它的关键属性。这种病毒的结构细节应该可以解释核糖核酸酶敏感性差异的原因。我们将启动对黄病毒非结构蛋白的结晶学研究。虽然这项工作才刚刚开始，但PPG将促进这些医学上重要病毒的合作努力。

We propose to use this Program Project Grant as an opportunity to explore a diverse set of important biological issues. The topics fit in well with the collaborative theme of this PPG and will allow my laboratory to explore several new, important avenues of structural virology. A major theme of this grant is to use structural biology methods to examine the processes involved in the vector transmission of plant viruses. Using cucumber mosaic virus (CMV) as a model for viruses that are transmitted via aphids without helper proteins, we plan to examine the structural motifs that interact with aphid mouthparts and are required for aphid transmission. Preliminary work has identified surface residues for aphid transmission. We propose to extend the resolution of the current CMV model. This, combined with immunological and cryo-TEM techniques, will allow use to examine aphid-virus interactions. With poty viruses, a helper protein, HC-Pro, is required to be transmitted by aphids. The N-terminal domain of HC-Pro is cysteine rich and is responsible for vector transmission and systemic spread throughout the plant. As a third approach to understanding transmission of plant viruses, we are pursuing structural studies on the carmovirus, cowpea mottle virus (CPMoV). We have determined the low resolution (approximately 23 angstroms) structure of CPMoV, and the capsid organization is very similar to that of another member of the Tombusviridae tomato bushy stunt virus (TBSV). However, unlike TBSV, CPMoV is not sensitive to RNAse- a property thought to be essential for its transmission by beetles. Structural details of this virus should elucidate the reason underlying these differences in RNAse sensitivity. We will initiate crystallographic studies on the non-structural proteins of the flaviviruses. While this work is just beginning, the PPG will facilitate collaborative efforts on these medically important viruses.