Rotavirus genomes are distributed between eleven distinct RNA molecules, all of which must be selectively co-packaged during virus assembly. This likely occurs through sequence-specific RNA interactions facilitated by the RNA chaperone NSP2. Here, we report that NSP2 auto-regulates its chaperone activity through its C-terminal region (CTR) that promotes RNA-RNA interactions by limiting its helix-unwinding activity. Unexpectedly, structural proteomics data revealed that the CTR does not directly interact with RNA, whilst accelerating RNA release from NSP2. Cryo-electron microscopy reconstructions of an NSP2-RNA complex reveal a highly conserved acidic patch poised towards RNA. Virus replication was abrogated by charge-disrupting mutations within the acidic patch but completely restored by charge-preserving mutations. Mechanistic similarities between NSP2 and the unrelated bacterial RNA chaperone Hfq suggest that accelerating RNA dissociation whilst promoting inter-molecular RNA interactions may be a widespread strategy of RNA chaperone recycling.

中文翻译：

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轮状病毒RNA伴侣置换和RNA退火的结构基础

轮状病毒基因组分布在11个不同的RNA分子之间，在病毒组装过程中必须选择性地将它们全部包装在一起。这很可能是通过RNA伴侣NSP2促进的序列特异性RNA相互作用而发生的。在这里，我们报告NSP2通过其C末端区域（CTR）通过限制其螺旋展开活性来促进RNA-RNA相互作用而自动调节其伴侣活性。出乎意料的是，结构蛋白质组学数据显示CTR不会直接与RNA相互作用，而会加速NSP2中RNA的释放。NSP2-RNA复合物的低温电子显微镜重建显示了一个高度保守的酸性贴片，其朝向RNA。酸性复制中的破坏电荷的突变消除了病毒复制，但由于保留电荷的突变而使病毒复制完全恢复。