Department of Biological Sciences, Mississippi State University, Starkville, MS 39759, USA.
Curr Opin Virol. 2021 Apr;47:32-37. doi: 10.1016/j.coviro.2020.12.004. Epub 2021 Jan 15.
Viroids are single-stranded circular noncoding RNAs that infect plants. The noncoding nature indicates that viroids must harness their RNA genomes to redirect host machinery for infection. Therefore, the viroid model provides invaluable opportunities for delineating fundamental principles of RNA structure-function relationships and for dissecting the composition and mechanism of RNA-related cellular machinery. There are two viroid families, Pospiviroidae and Avsunviroidae. Members of both families replicate via the RNA-based rolling-circle mechanism with some variations. Viroid replication is generally divided into three steps: transcription, cleavage, and ligation. Decades of studies have uncovered numerous viroid RNA structures with a regulatory role in replication and multiple enzymes critical for the three replication steps. This review discusses these findings and highlights the latest discoveries. Future studies will continue to elucidate regulatory factors and mechanism of host machinery exploited by viroids and provide new insights into host-viroid interactions in the context of pathogenesis.
类病毒是感染植物的单链环状非编码 RNA。非编码性质表明，类病毒必须利用其 RNA 基因组来重新引导宿主机制以进行感染。因此，类病毒模型为阐明 RNA 结构-功能关系的基本原理以及解析与 RNA 相关的细胞机制的组成和机制提供了宝贵的机会。有两个类病毒家族，Pospiviroidae 和 Avsunviroidae。这两个家族的成员都通过 RNA 为基础的滚环机制进行复制，有一些变化。类病毒的复制通常分为转录、切割和连接三个步骤。数十年来的研究揭示了许多具有复制调节作用的类病毒 RNA 结构以及对三个复制步骤至关重要的多种酶。本文讨论了这些发现，并强调了最新的发现。未来的研究将继续阐明类病毒利用的调节因子和宿主机制的机制，并在发病机制的背景下为宿主-类病毒相互作用提供新的见解。
