Cap-independent translation conferred by the 5′ leader of tobacco etch virus is eukaryotic initiation factor 4G dependent
Cap-independent translation conferred by the 5′ leader of tobacco etch virus is eukaryotic initiation factor 4G dependent
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DOI：
10.1128/jvi.75.24.12141-12152.2001
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发表时间：
2001-12-01
影响因子：
5.4
通讯作者：
Gallie, DR
中科院分区：
文献类型：
--
作者：
Gallie, DR
烟草蚀纹病毒（TEV）基因组RNA的5'前导序列指导从天然脱帽病毒mRNA的有效翻译。TEV 143核苷酸前导序列内的两个不同区域即使存在于双顺反子mRNA的顺反子间区域中也赋予帽非依赖性体内翻译，这表明TEV前导序列含有内部核糖体进入位点（IRES）。在这项研究中，对TEV IRES活性的要求进行了研究。TEV IRES在竞争性条件下体外增强单顺反子或双顺反子mRNA的翻译，即，在高RNA浓度下或在部分耗尽真核起始因子4F（eIF4F）和eIFiso4F（植物中的两种帽结合复合物）的裂解物中。当eIF4F和eIFiso4F中减少的裂解物补充有eIF4F（或在较小程度上补充有eIFiso4F）时，TEV IRES在这些条件下赋予的翻译优势丧失，但当补充有eIF4E、eIFiso4E、eIF4A或eIF4B时则不会丧失。eIF4G是eIF4F的大亚基，负责TEV IRES赋予的竞争优势。TEV IRES活性通过poly（A）结合蛋白适度增强。这些观察结果表明，TEV IRES通过特异性涉及eIF4G的机制指导帽非依赖性翻译。
The 5' leader of tobacco etch virus (TEV) genomic RNA directs efficient translation from the naturally uncapped viral mRNA. Two distinct regions within the TEV 143-nucleotide leader confer cap-independent translation in vivo even when present in the intercistronic region of a discistronic mRNA, indicating that the TEV leader contains an internal ribosome entry site (IRES). In this study, the requirements for TEV IRES activity were investigated. The TEV IRES enhanced translation of monocistronic or dicistronic mRNAs in vitro under competitive conditions, i.e., at high RNA concentration or in lysate partially depleted of eukaryotic initiation factor 4F (eIF4F) and eIFiso4F, the two cap binding complexes in plants. The translational advantage conferred by the TEV IRES under these conditions was lost when the lysate reduced in eIF4F and eIFiso4F was supplemented with eIF4F (or, to a lesser extent, eIFiso4F) but not when supplemented with eIF4E, eIFiso4E, eIF4A, or eIF4B. eIF4G, the large subunit of eIF4F, was responsible for the competitive advantage conferred by the TEV IRES. TEV IRES activity was enhanced moderately by the poly(A)-binding protein. These observations suggest that the TEV IRES directs cap-independent translation through a mechanism that involves eIF4G specifically.