Structure and function of Borna disease virus polymerase

项目摘要/摘要 非分段负链(NNS)RNA病毒是高度多样化的真核病毒，包括 重要的人类病原体(例如狂犬病、尼帕、埃博拉)。大多数NNS RNA病毒都是在黑色素瘤的细胞质中复制的 博尔纳病病毒1(BoDV-1)是一种独特的NNS RNA病毒，可在细胞核内复制。BoDV- 1是动物和人类致命神经疾病的病原体，尽管在极少数情况下。有趣的是， 内源性博尔纳病毒样分子作为古代博尔纳病毒的化石在各种不同的基因组中被发现 包括人类在内的脊椎动物，表明博尔纳病毒和脊椎动物之间存在相互作用 进化过程中的宿主。因此，阐明博尔纳病毒在宿主细胞中复制的独特策略是重要的。 不仅要了解博尔纳病毒的基本生物学，而且要开发针对 具有人畜共患病潜力的博尔纳病毒。这个项目的目标是阐明RNA的酶作用- 由BoDV-1、L和P蛋白组成的转录和转录依赖核糖核酸聚合酶复合体 复制。我们推测(1)BoDV-1 L蛋白具有进行基因组测定的酶活性 转录和复制；(2)多聚体P蛋白在维持 L蛋白的转录活性状态。这些假说将通过特定的目的来验证，以澄清 BDV-1 L蛋白在核糖核酸合成和加工中的作用和(2)P蛋白在病毒形成中的作用 转录活性的RdRp复合体。在目标1中，我们将剖析形成的机制 基因组的独特末端和mRNAs上的5‘末端帽核心结构与BoDV-1 L-P复合体。 在目标2中，我们将求解BoDV-1 L-P复合体的三维结构，并研究其激活机制 L蛋白和多聚体P蛋白在核糖核酸合成中的差异。总的来说，这项研究将推动我们的 了解BoDV-1的L蛋白及其辅助蛋白如何进行核糖核酸的合成和加工 P因子蛋白。此外，本研究将揭示RdRp和RdRp在结构上的相似和差异 核质复制NNS RNA病毒的复合体。

Project Summary/Abstract Non-segmented negative strand (NNS) RNA viruses are highly diversified eukaryotic viruses including significant human pathogens (e.g., rabies, Nipah, Ebola). Most NNS RNA viruses replicate in the cytoplasm of host cells, whereas Borna disease virus 1 (BoDV-1), a unique NNS RNA virus, replicates in the nucleus. BoDV- 1 is a causative agent of fatal neurological diseases in animals and humans, although in rare cases. Interestingly, endogenous bornavirus-like elements were discovered as fossils of ancient bornaviruses in genomes of various vertebrates including humans, indicating that there have been interactions between bornaviruses and vertebrate hosts during evolution. Thus, elucidation of unique strategies of bornaviruses to replicate in host cells is important not only to understand the basic biology of bornaviruses but also to develop therapeutic targets against bornaviruses with zoonotic potential. The goal of this project is to elucidate the enzymatic roles of the RNA- dependent RNA polymerase (RdRp) complex composed of the BoDV-1 L and P proteins in transcription and replication. We hypothesize that (1) the BoDV-1 L protein has enzymatic activities to carry out genome transcription and replication and (2) the multimeric P protein plays structural roles in maintaining a transcriptionally active state of the L protein. These hypotheses will be tested by the specific aims to elucidate the roles of (1) the BoDV-1 L protein in RNA synthesis and processing and (2) the P protein in the formation of a transcriptionally active RdRp complex. In Aim 1, we will dissect the mechanisms underlying the formation of the unique termini of the genome and the 5′-terminal cap core structure on mRNAs with the BoDV-1 L-P complex. In Aim 2, we will solve a 3D structure of the BoDV-1 L-P complex and investigate the mechanism of the activation of the L protein with the multimeric P protein in RNA synthesis. Collectively, this study will advance our understanding of how the L protein of BoDV-1 carries out RNA synthesis and processing together with its co- factor P protein. Furthermore, this study will reveal structural similarities and differences between RdRp complexes of nuclear- and cytoplasmic- replicating NNS RNA viruses.