Hyodo Kiwamu, Nagai Hikari, Okuno Tetsuro
Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan.
Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
Virology. 2017 Dec;512:74-82. doi: 10.1016/j.virol.2017.09.008. Epub 2017 Sep 21.
The genome of red clover necrotic mosaic virus is divided into two positive-stranded RNA molecules of RNA1 and RNA2, which have no 5' cap structure and no 3' poly(A) tail. Previously, we showed that any mutations in the cis-acting RNA replication elements of RNA2 abolished its cap-independent translational activity, suggesting a strong link between RNA replication and translation. Here, we investigated the functions of the 5' untranslated region (UTR) of RNA2 and revealed that the basal stem-structure (5'BS) predicted in the 5' UTR is essential for robust RNA replication. Interestingly, RNA2 mutants with substitution or deletion in the right side of the 5'BS showed strong translational activity, despite their impaired replication competency. Furthermore, nucleotide sequences other than the 5'BS of the 5' UTR were essential to facilitate the replication-associated translation. Overall, these cis-acting RNA elements seem to coordinately regulate the balance between RNA replication and replication-associated translation.
红三叶草坏死花叶病毒的基因组被分为RNA1和RNA2两个正链RNA分子,它们没有5'帽结构,也没有3'聚腺苷酸尾。此前,我们发现RNA2的顺式作用RNA复制元件中的任何突变都会消除其不依赖帽的翻译活性,这表明RNA复制与翻译之间存在紧密联系。在此,我们研究了RNA2的5'非翻译区(UTR)的功能,发现5'UTR中预测的基础茎结构(5'BS)对于强大的RNA复制至关重要。有趣的是,在5'BS右侧有取代或缺失的RNA2突变体尽管复制能力受损,但仍表现出很强的翻译活性。此外,5'UTR的5'BS以外的核苷酸序列对于促进与复制相关的翻译至关重要。总体而言,这些顺式作用RNA元件似乎协同调节RNA复制与复制相关翻译之间的平衡。