Potyvirus genome-linked protein, VPg, directly affects wheat germ in vitro translation -: Interactions with translation initiation factors eif4f and eifiso4f
Potyvirus genome-linked protein, VPg, directly affects wheat germ in vitro translation -: Interactions with translation initiation factors eif4f and eifiso4f
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DOI：
10.1074/jbc.m703356200
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发表时间：
2008-01-18
影响因子：
4.8
通讯作者：
Goss, Dixie J.
中科院分区：
文献类型：
--
作者：
Khan, Mateen A.;Miyoshi, Hiroshi;Goss, Dixie J.
马铃薯Y病毒基因组连锁蛋白VPg与翻译起始因子eIF4E和eIFiso4E相互作用，但其在蛋白质合成中的作用尚未阐明。我们表明，另外的VPg小麦胚芽提取物导致的无帽病毒mRNA的翻译和抑制加帽病毒mRNA的翻译增强。这为未加帽的病毒mRNA提供了显著的竞争优势。为了理解这些效应的分子基础，我们已经表征了VPg与eIF4F、eIFiso4F和来自烟草蚀纹病毒的结构化RNA（TEV RNA）的相互作用。当VPg与eIF4F形成复合物时，与单独的eIF4F相比，对TEV RNA的亲和力增加了4倍以上（分别为19.4和79.0 nM）。eIF4F与TEV RNA的结合亲和力与翻译效率相关。VPg增强eIFiso4F与TEV RNA的结合1.6倍（178 nM与108 nM相比）。eIF4F和eIFiso4F与VPg的动力学研究显示，与eIF4F中心点VPg相比，eIFiso4F中心点VPg的结合快2.6倍。eIFiso4F的解离速率类似于eIF4F与VPg的解离速率的2.9倍。这些数据表明eIFiso4F可与eIF4F动力学竞争VPg结合。本文提供的定量数据表明了一种模型，其中eIF4F中心点VPg相互作用通过增加eIF4F对TEV RNA的亲和力来增强帽非依赖性翻译。这是VPg直接参与翻译启动的第一个证据。
Potyvirus genome linked protein, VPg, interacts with translation initiation factors eIF4E and eIFiso4E, but its role in protein synthesis has not been elucidated. We show that addition of VPg to wheat germ extract leads to enhancement of uncapped viral mRNA translation and inhibition of capped viral mRNA translation. This provides a significant competitive advantage to the uncapped viral mRNA. To understand the molecular basis of these effects, we have characterized the interaction of VPg with eIF4F, eIFiso4F, and a structured RNA derived from tobacco etch virus (TEV RNA). When VPg formed a complex with eIF4F, the affinity for TEV RNA increased more than 4-fold compared with eIF4F alone (19.4 and 79.0 nM, respectively). The binding affinity of eIF4F to TEV RNA correlates with translation efficiency. VPg enhanced eIFiso4F binding to TEV RNA 1.6-fold ( 178 nM compared with 108 nM). Kinetic studies of eIF4F and eIFiso4F with VPg show similar to 2.6-fold faster association for eIFiso4F center dot VPg as compared with eIF4F center dot VPg. The dissociation rate was similar to 2.9-fold slower for eIFiso4F than eIF4F with VPg. These data demonstrate that eIFiso4F can kinetically compete with eIF4F for VPg binding. The quantitative data presented here suggest a model where eIF4F center dot VPg interaction enhances cap-independent translation by increasing the affinity of eIF4F for TEV RNA. This is the first evidence of direct participation of VPg in translation initiation.