Structure and function of Borna disease virus polymerase

项目概要/摘要 非节段负链（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、尼帕病毒、埃博拉病毒）。大多数NNS RNA病毒在细胞质中复制， 而博尔纳病病毒1（BoDV-1），一种独特的NNS RNA病毒，在细胞核中复制。BoDV- 1是动物和人类致命神经系统疾病的病原体，尽管在罕见的情况下。有趣的是， 内源性博尔纳病毒样元件被发现作为古博尔纳病毒的化石存在于各种 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 不仅要了解博纳病毒的基本生物学，还要开发治疗靶点， 具有人畜共患潜力的博纳病毒。该项目的目标是阐明RNA的酶作用， 转录中由BoDV-1 L和P蛋白组成的依赖性RNA聚合酶（RdRp）复合物， 复制的我们推测（1）BoDV-1 L蛋白具有进行基因组测序的酶活性， （2）多聚体P蛋白在维持转录和复制中起着结构性作用。 L蛋白的转录活性状态。这些假设将通过具体目标来验证以阐明 （1）BoDV-1 L蛋白在RNA合成和加工中的作用，以及（2）P蛋白在 转录活性RdRp复合物。在目标1中，我们将剖析 基因组的独特末端和具有BoDV-1 L-P复合物的mRNA上的5′-末端帽核心结构。 在目标2中，我们将解决BoDV-1 L-P复合物的3D结构，并研究活化机制。 L蛋白和多聚体P蛋白在RNA合成中的相互作用。总的来说，这项研究将推动我们的 了解BoDV-1的L蛋白如何进行RNA合成和加工， 因子P蛋白此外，本研究将揭示RdRp之间的结构相似性和差异 核和细胞质复制的NNS RNA病毒的复合物。

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.