The genomes of RNA viruses contain regulatory elements of varying complexity. Many plus-strand RNA viruses employ largescale intra-genomic RNA-RNA interactions as a means to control viral processes. Here, we describe an elaborate RNA structure formed by multiple distant regions in a tombusvirus genome that activates transcription of a viral subgenomic mRNA. The initial step in assembly of this intramolecular RNA complex involves the folding of a large viral RNA domain, which generates a discontinuous binding pocket. Next, a distally-located protracted stem-loop RNA structure docks, via base-pairing, into the binding site and acts as a linchpin that stabilizes the RNA complex and activates transcription. A multi-step RNA folding pathway is proposed in which rate-limiting steps contribute to a delay in transcription of the capsid protein-encoding viral subgenomic mRNA. This study provides an exceptional example of the complexity of genome-scale viral regulation and offers new insights into the assembly schemes utilized by large intra-genomic RNA structures.

中文翻译：

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通过逐步大规模折叠 RNA 病毒基因组来激活病毒转录。


RNA 病毒的基因组包含不同复杂性的调控元件。许多正链 RNA 病毒利用大规模基因组内 RNA-RNA 相互作用作为控制病毒过程的手段。在这里，我们描述了由烟草病毒基因组中多个遥远区域形成的复杂RNA结构，该结构激活病毒亚基因组mRNA的转录。这种分子内 RNA 复合物组装的第一步涉及大病毒 RNA 结构域的折叠，从而产生不连续的结合袋。接下来，位于远端的延长茎环RNA结构通过碱基配对对接至结合位点，并充当稳定RNA复合物并激活转录的关键。提出了一种多步骤 RNA 折叠途径，其中限速步骤有助于延迟编码衣壳蛋白的病毒亚基因组 mRNA 的转录。这项研究为基因组规模病毒调控的复杂性提供了一个特殊的例子，并为大型基因组内 RNA 结构所利用的组装方案提供了新的见解。