Evidence that avian reovirus σNS is an RNA chaperone: implications for genome segment assortment.
Evidence that avian reovirus σNS is an RNA chaperone: implications for genome segment assortment.
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DOI：
10.1093/nar/gkv639
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发表时间：
2015-08-18
影响因子：
14.9
通讯作者：
Tuma R
中科院分区：
文献类型：
--
作者：
Borodavka A;Ault J;Stockley PG;Tuma R
呼肠孤病毒是人类、动物和植物的重要病原体，含有10-12个双链基因组RNA片段。控制这些病毒基因组片段的分类和包装的机制仍然知之甚少。病毒基因组片段前体之间的RNA-蛋白质和RNA-RNA相互作用参与了这一过程。虽然非结构病毒核糖核酸结合蛋白，如禽呼肠孤病毒σNS，是病毒复制所必需的，但它们帮助包装的机制尚不清楚。在这里，我们证明了σNS在体外组装成稳定的拉长六聚体，它以高亲和力结合单链核酸，但几乎没有序列特异性。利用系综和单分子荧光光谱，我们发现σNS还与部分双链的核糖核酸结合，导致逐渐的螺旋解旋。该六聚体可以与多个RNA分子结合，并表现出链退火活性，从而介导亚稳定的分子内茎环向更稳定的异双链的转化。我们证明，在片段分类和包装过程中，ARVRNANS作为σ伴侣促进了基因组前体之间的特定RNARNA相互作用。
Reoviruses are important human, animal and plant pathogens having 10–12 segments of double-stranded genomic RNA. The mechanisms controlling the assortment and packaging of genomic segments in these viruses, remain poorly understood. RNA–protein and RNA–RNA interactions between viral genomic segment precursors have been implicated in the process. While non-structural viral RNA-binding proteins, such as avian reovirus σNS, are essential for virus replication, the mechanism by which they assist packaging is unclear. Here we demonstrate that σNS assembles into stable elongated hexamers in vitro, which bind single-stranded nucleic acids with high affinity, but little sequence specificity. Using ensemble and single molecule fluorescence spectroscopy, we show that σNS also binds to a partially double-stranded RNA, resulting in gradual helix unwinding. The hexamer can bind multiple RNA molecules and exhibits strand-annealing activity, thus mediating conversion of metastable, intramolecular stem-loops into more stable heteroduplexes. We demonstrate that the ARV σNS acts as an RNA chaperone facilitating specific RNA–RNA interactions between genomic precursors during segment assortment and packaging.