Satellite RNA-Derived Small Interfering RNA satsiR-12 Targeting the 3′ Untranslated Region of Cucumber Mosaic Virus Triggers Viral RNAs for Degradation
Satellite RNA-Derived Small Interfering RNA satsiR-12 Targeting the 3′ Untranslated Region of Cucumber Mosaic Virus Triggers Viral RNAs for Degradation
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DOI：
10.1128/jvi.05806-11
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发表时间：
2011-12-01
影响因子：
5.4
通讯作者：
Guo, Hui-Shan
中科院分区：
文献类型：
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作者：
Zhu, Hui;Duan, Cheng-Guo;Guo, Hui-Shan
RNA沉默通过靶向辅助病毒及其卫星RNA（satRNA）提供针对RNA病毒的保护。推测与Argonaute（AGO）蛋白结合的病毒衍生的小干扰RNA（vsiRNA）参与沉默过程。在这里，我们表明，靶向病毒RNA的vsiRNA触发宿主RNA依赖性RNA聚合酶6（RDR 6）介导的病毒RNA降解。我们证实，satRNA衍生的小干扰RNA（satsiRNA）可以与不同的AGO蛋白在植物。最常克隆的satsiR-12被预测在3'非翻译区（3' UTR）的上游区域与黄瓜花叶病毒（CMV）RNA不完全匹配。此外，人工satsiR-12（asatsiR-12）介导了具有satsiR-12靶位点的绿色荧光蛋白（GFP）传感器构建体的切割。asatsiR-12还介导了2b缺陷型CMV（CMV Delta 2b）感染的本氏烟草中病毒RNA的减少。在其中RDR 6沉默的CMV Delta 2b感染的RDR 6 i植物中未观察到减少。在用含有2b的CMV感染后，在任一基因型的植物中均未观察到病毒RNA的减少，表明在RDR 6存在下asatsiR-12介导的病毒RNA减少被2b蛋白抑制。我们的结果表明，satsiR-12靶向CMV RNA的3' UTR触发了RDR 6依赖性抗病毒沉默。在2b和satRNA存在下，野生型CMV RNA和抗satsiR-12突变体RNA 1的竞争实验证明了2b蛋白对CMV RNA的satsiR-12相关降解的抑制作用，揭示了2b蛋白在天然CMV感染中的实质性抑制功能。我们的数据为satsiRNA在病毒感染的最终结果中宿主、病毒和satRNA之间的稳态相互作用中的重要生物学功能提供了证据。
RNA silencing provides protection against RNA viruses by targeting both the helper virus and its satellite RNA (satRNA). Virus-derived small interfering RNAs (vsiRNAs) bound with Argonaute (AGO) proteins are presumed participants in the silencing process. Here, we show that a vsiRNA targeted to virus RNAs triggers the host RNA-dependent RNA polymerase 6 (RDR6)-mediated degradation of viral RNAs. We confirmed that satRNA-derived small interfering RNAs (satsiRNAs) could be associated with different AGO proteins in planta. The most frequently cloned satsiRNA, satsiR-12, was predicted to imperfectly match to Cucumber mosaic virus (CMV) RNAs in the upstream area of the 3' untranslated region (3' UTR). Moreover, an artificial satsiR-12 (asatsiR-12) mediated cleavage of a green fluorescent protein (GFP) sensor construct harboring the satsiR-12 target site. asatsiR-12 also mediated reduction of viral RNAs in 2b-deficient CMV (CMV Delta 2b)-infected Nicotiana benthamiana. The reduction was not observed in CMV Delta 2b-infected RDR6i plants, in which RDR6 was silenced. Following infection with 2b-containing CMV, the reduction in viral RNAs was not observed in plants of either genotype, indicating that the asatsiR-12-mediated reduction of viral RNAs in the presence of RDR6 was inhibited by the 2b protein. Our results suggest that satsiR-12 targeting the 3' UTR of CMV RNAs triggered RDR6-dependent antiviral silencing. Competition experiments with wild-type CMV RNAs and anti-satsiR-12 mutant RNA1 in the presence of 2b and satRNA demonstrate the inhibitory effect of the 2b protein on the satsiR-12-related degradation of CMV RNAs, revealing a substantial suppressor function of the 2b protein in native CMV infection. Our data provide evidence for the important biological functions of satsiRNAs in homeostatic interactions among the host, virus, and satRNA in the final outcome of viral infection.