Distinct Regions of Human eIF3 Are Sufficient for Binding to the HCV IRES and the 40S Ribosomal Subunit
Distinct Regions of Human eIF3 Are Sufficient for Binding to the HCV IRES and the 40S Ribosomal Subunit
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DOI：
10.1016/j.jmb.2010.07.054
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发表时间：
2010-10-22
影响因子：
5.6
通讯作者：
Cate, Jamie H. D.
中科院分区：
文献类型：
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作者：
Cai, Qi;Todorovic, Aleksandar;Cate, Jamie H. D.
丙型肝炎病毒（HCV）基因组RNA的翻译始于其5 '非翻译区的内部核糖体进入位点（IRES），并且需要翻译起始因子的最小子集，即真核起始因子（eIF） 2和eIF3。低分辨率结构信息揭示了HCV IRES RNA如何结合人eIF3和40S核糖体亚基并定位起始密码子。然而，HCV IRES RNA与翻译机制之间相互作用的确切性质仍然未知。通过有限的蛋白水解和质谱分析，我们发现人类eIF3的不同区域足以与HCV IRES RNA和40S亚基结合。值得注意的是，eIF3亚基eIF3b受到HCV IRES RNA结合的保护，但与eIF3e、eIF3f、eIF3h和eIF31亚基相比，eIF3b暴露在复合物中。有限的蛋白水解表明，eIF3与40S核糖体亚基的结合是通过许多冗余相互作用发生的，这些相互作用可以相互补偿。这些数据表明HCV IRES如何结合eIF3的特定区域以靶向病毒基因组RNA的翻译机制，并为完整的人类eIF3结构建模提供了框架。(C) 2010 Elsevier Ltd.版权所有。
Translation of the hepatitis C virus (HCV) genomic RNA initiates from an internal ribosome entry site (IRES) in its 5 ' untranslated region and requires a minimal subset of translation initiation factors to occur, namely eukaryotic initiation factor (eIF) 2 and eIF3. Low-resolution structural information has revealed how the HCV IRES RNA binds human eIF3 and the 40S ribosomal subunit and positions the start codon for initiation. However, the exact nature of the interactions between the HCV IRES RNA and the translational machinery remains unknown. Using limited proteolysis and mass spectrometry, we show that distinct regions of human eIF3 are sufficient for binding to the HCV IRES RNA and the 40S subunit. Notably, the eIF3 subunit eIF3b is protected by HCV IRES RNA binding, yet is exposed in the complex when compared to subunits eIF3e, eIF3f, eIF3h, and eIF31. Limited proteolysis reveals that eIF3 binding to the 40S ribosomal subunit occurs through many redundant interactions that can compensate for each other. These data suggest how the HCV IRES binds to specific regions of eIF3 to target the translational machinery to the viral genomic RNA and provide a framework for modeling the architecture of intact human eIF3. (C) 2010 Elsevier Ltd. All rights reserved.