Structural studies of the eIF4E-VPg complex reveal a direct competition for capped RNA: Implications for translation
Structural studies of the eIF4E-VPg complex reveal a direct competition for capped RNA: Implications for translation
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DOI：
10.1073/pnas.1904752116
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发表时间：
2019-11-26
影响因子：
11.1
通讯作者：
Borden, Katherine L. B.
中科院分区：
文献类型：
--
作者：
de Oliveira, Luciana Coutinho;Volpon, Laurent;Borden, Katherine L. B.
病毒改变了我们对哺乳动物RNA加工的理解，包括促进发现RNA 5'端的甲基-7-鸟苷（m（7）G）帽。m（7）G帽是RNA结合真核生物翻译起始因子eIF 4 E所必需的，并与植物和动物界的翻译机制相关。马铃薯Y病毒属衍生的病毒基因组连接蛋白（VPg）与病毒基因组RNA（gRNA）的5'端共价结合，并与宿主eIF 4 E结合以成功感染。解释这些观察结果的不同模型提出了eIF 4 E接合的未知模式或VPg对m（7）G帽结合位点的竞争。为了剖析这些可能性，我们解析了VPg的结构，揭示了以前未知的三维（3D）折叠，并使用NMR和生物物理技术表征了VPg-eIF 4 E复合物。VPg直接结合eIF 4 E的帽结合位点并竞争m（7）G帽类似物结合。在人类细胞中，VPg抑制eIF 4 E依赖的RNA输出、翻译和致癌转化。此外，VPg与eIF 4 E-eIF 4G形成三聚体复合物，eIF 4 E结合VPg-荧光素酶RNA缀合物，并且这些VPg-RNA缀合物是翻译的模板。信息学分析显示VPg和人类驱动蛋白EGS之间的结构相似性。一致地，EG 5以与VPg类似的方式直接结合eIF 4 E，表明这种形式的接合在马铃薯Y病毒属之外是相关的。总之，我们揭示了一种前所未有的控制和参与eIF 4 E的模式，并表明VPg-RNA缀合物在功能上参与eIF 4 E。因此，马铃薯Y病毒VPg提供了一种独特的模型系统来询问eIF 4 E。
Viruses have transformed our understanding of mammalian RNA processing, including facilitating the discovery of the methyl-7-guanosine (m(7)G) cap on the 5' end of RNAs. The m(7)G cap is required for RNAs to bind the eukaryotic translation initiation factor eIF4E and associate with the translation machinery across plant and animal kingdoms. The potyvirus-derived viral genome-linked protein (VPg) is covalently bound to the 5' end of viral genomic RNA (gRNA) and associates with host eIF4E for successful infection. Divergent models to explain these observations proposed either an unknown mode of eIF4E engagement or a competition of VPg for the m(7)G cap-binding site. To dissect these possibilities, we resolved the structure of VPg, revealing a previously unknown 3-dimensional (3D) fold, and characterized the VPg-eIF4E complex using NMR and biophysical techniques. VPg directly bound the cap-binding site of eIF4E and competed for m(7)G cap analog binding. In human cells, VPg inhibited eIF4E-dependent RNA export, translation, and oncogenic transformation. Moreover, VPg formed trimeric complexes with eIF4E-eIF4G, eIF4E bound VPg-luciferase RNA conjugates, and these VPg-RNA conjugates were templates for translation. Informatic analyses revealed structural similarities between VPg and the human kinesin EGS. Consistently, EG5 directly bound eIF4E in a similar manner to VPg, demonstrating that this form of engagement is relevant beyond potyviruses. In all, we revealed an unprecedented modality for control and engagement of eIF4E and show that VPg-RNA conjugates functionally engage eIF4E. As such, potyvirus VPg provides a unique model system to interrogate eIF4E.