Viroid models to study evolution of RNA trafficking motifs for host adaptation

包括类病毒和病毒在内的感染性RNA必须在细胞之间运输以建立全身感染。这个项目解决了非编码RNA结构基序在宿主适应中的作用。它测试了以下假设：（i）感染性RNA可以快速进化新的三维（3D）基序，用于作为宿主适应的手段进行运输，以及（ii）不同的感染性RNA可以进化不同的运输基序，用于适应相同的宿主。这一假设是从下列观察中得出的。首先，当马铃薯纺锤块茎类病毒（PSTVd）的一个称为环19的特定基序被消除以消除实验宿主植物本氏烟草（Nicotiana benthamiana）中的贩运（但不是复制）时，一个新的环（环19*）进化以恢复贩运。其次，一些类病毒，如啤酒花矮化类病毒（HSVd），在序列上与PSTVd有显著差异，但也能感染N。系统性地使用本萨米亚那。为了检验这一假设，将进行以下实验：1）阐明环19的3D结构并确定环19* 是否类似地结构化，2）确定环19和环19* 起作用的细胞边界，和3）执行基因组-广泛的HSVd运输基序的突变鉴定，并将它们与已经确定的PSTVd基序进行相似性和差异性比较。贡献了关于感染性RNA进化的分子机制的新知识，以及控制不同RNA系统性运输的统一和独特原则。开发的新研究工具和实验系统也可能有助于改变RNA结构-功能关系的一般原理。该项目将培训本科生/研究生开发尖端的跨学科方法来研究基本的生物学问题，并帮助加强小学/初中/高中学生的科学教育，包括传统上代表性不足的群体。

Infectious RNAs including viroids and viruses must traffic between cells in order to establish systemic infection. This project addresses the role of noncoding RNA structural motifs for trafficking in host adaptation. It tests the hypothesis that (i) an infectious RNA can rapidly evolve new three-dimensional (3D) motifs for trafficking as a means of host adaptation, and (ii) different infectious RNAs can evolve distinct trafficking motifs for adaptation to the same host. This hypothesis was developed from the following observations. First, when a particular motif, called loop 19, of Potato spindle tuber viroid (PSTVd) was obliterated to abolish trafficking (but not replication) in the experimental host plant Nicotiana benthamiana, a new loop (loop 19*) evolved to restore trafficking. Second, some viroids, such as Hop stunt viroid (HSVd), differ significantly in sequences from PSTVd but also can infect N. benthamiana systemically. To test this hypothesis, the following experiments will be performed: 1) to elucidate the 3D structure of loop 19 and determine whether loop 19* is similarly structured, 2) to determine the cellular boundary at which loop 19 and loop 19* function, and 3) to perform a genome-wide mutational identification of HSVd trafficking motifs and compare them with the PSTVd motifs that have already been identified for similarities and differences.This project will contribute new knowledge about the molecular mechanisms underlying the evolution of infectious RNAs and broadly the unifying and unique principles controlling the systemic trafficking of different RNAs. New research tools and experimental systems developed may also help transform research on the general principles of RNA structure-function relationships. This project will train undergraduate/graduate students in developing cutting-edge cross-disciplinary approaches to study fundamental biological problems, and help enhance science education for elementary/middle/high school students, including traditionally underrepresented groups.