Analysis of a 3′-translation enhancer in a tombusvirus:: A dynamic model for RNA-RNA interactions of mRNA termini
Analysis of a 3′-translation enhancer in a tombusvirus:: A dynamic model for RNA-RNA interactions of mRNA termini
复制标题
DOI：
10.1261/rna.69506
复制
发表时间：
2006-07-01
期刊：
影响因子：
4.5
通讯作者：
White, K. Andrew
中科院分区：
文献类型：
--
作者：
Fabian, Marc R.;White, K. Andrew
番茄丛矮病毒（Tomato bushy stunt virus）是一种（+）链RNA病毒，既不是5 ′-加帽的，也不是3 ′-聚腺苷酸化的。相反，病毒蛋白的翻译由RNA元件介导，即位于其3'非翻译区（UTR）的3'-帽非依赖性翻译增强子（3 'CITE）。3 'CITE被认为是将翻译机制募集到病毒信息中，而3' CITE和5' UTR之间的长距离RNA-RNA相互作用被认为是将43 S核糖体亚基递送到病毒mRNA的5'端。在这里，我们提供了第一个证据表明，5'非翻译区和3' CITE物理相互作用。突变分析表明，这种RNA-RNA相互作用在体外的形成与体内的有效翻译密切相关，从而支持其功能相关性。对3 'CITE的其他分析证实了总体Y形RNA二级结构，并证明了许多次要结构特征对于病毒mRNA的有效翻译的重要性。对5' UTR作用的功能研究表明，尽管不存在帽结构，但43 S亚基在5'端装载并在3'方向扫描。这些结果表明，5 '-3' RNA-RNA相互作用可能被破坏扫描核糖体亚基，并提出了一个动态模型的mRNA末端的相互作用在主动翻译。
Tomato bushy stunt virus is a (+)-strand RNA virus that is neither 5'-capped nor 3'-polyadenylated. Translation of viral proteins is instead mediated by an RNA element, the 3'-cap-independent translational enhancer (3'CITE), which is located in its 3' untranslated region (UTR). The 3'CITE is proposed to recruit the translational machinery to the viral message, while a long-distance RNA-RNA interaction between the 3'CITE and 5' UTR is thought to deliver the 43S ribosomal subunit to the 5' end of the viral mRNA. Here we provide the first evidence that the 5' UTR and 3'CITE interact physically. Mutational analysis showed that formation of this RNA-RNA interaction in vitro correlates well with efficient translation in vivo, thus supporting its functional relevance. Other analyses of the 3'CITE confirmed an overall Y-shaped RNA secondary structure and demonstrated the importance of numerous minor structural features for efficient translation of viral mRNAs. Functional studies on the role of the 5' UTR revealed that despite the absence of a cap structure, 43S subunits load at the very 5' end and scan in a 3' direction. These results indicate that the 5'-3' RNA-RNA interaction is likely disrupted by scanning ribosomal subunits and suggest a dynamic model for the interaction of mRNA termini during active translation.