Multiple elements in the eIF4G1 N-terminus promote assembly of elF4G1•PABP mRNPs in vivo
Multiple elements in the eIF4G1 N-terminus promote assembly of elF4G1•PABP mRNPs in vivo
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DOI：
10.1038/emboj.2010.312
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发表时间：
2011-01-19
期刊：
影响因子：
11.4
通讯作者：
Hinnebusch, Alan G.
中科院分区：
文献类型：
--
作者：
Park, Eun-Hee;Walker, Sarah E.;Hinnebusch, Alan G.
eIF 4G是eIF 4F复合物的支架亚基，其与eIF 4 E和多聚腺苷酸结合蛋白（PABP）的结合结构域被认为可增强激活的eIF 4F中心点mRNA中心点PABP复合物的形成，该复合物能够募集43 S前起始复合物。我们发现酵母eIF 4G 1的N-末端结构域（NTD）中的RNA结合区（RNA 1）可以在功能上替代PABP结合片段，以拯救eIF 4G 1 -459突变体的功能，该突变体因eIF 4 E结合而受损。在细胞提取物中测定RNA依赖性PABP-eIF 4G缔合表明，RNA 1、PABP结合结构域和这些片段之间的两个保守元件（Box 1和Box 2）在形成天然eIF 4G中心点mRNA中心点PABP复合物中具有重叠功能。体外实验证实了RNA 1在稳定eIF 4G-mRNA结合中的作用，并进一步表明RNA 1和Box 1除了促进RNA结合外，还通过eIF 4G 1 NTD促进PABP结合。我们的研究结果表明，PABP-eIF 4G协会只是几个相互作用，稳定eIF 4F中心点mRNA复合物之一，并强调，闭环mRNP形成通过PABP-eIF 4G相互作用是不必要的在体内。有趣的是，eIF 4G 1中的另外两个RNA结合区域在eIF 4F中心点mRNA组装的下游具有关键功能。The EMBO Journal（2011）30，302-316. doi：10.1038/daj.2010.312; 2010年12月7日在线发布
eIF4G is the scaffold subunit of the eIF4F complex, whose binding domains for eIF4E and poly(A)-binding protein (PABP) are thought to enhance formation of activated eIF4F center dot mRNA center dot PABP complexes competent to recruit 43S pre-initiation complexes. We found that the RNA-binding region (RNA1) in the N-terminal domain (NTD) of yeast eIF4G1 can functionally substitute for the PABP-binding segment to rescue the function of an eIF4G1-459 mutant impaired for eIF4E binding. Assaying RNA-dependent PABP-eIF4G association in cell extracts suggests that RNA1, the PABP-binding domain, and two conserved elements (Box1 and Box2) between these segments have overlapping functions in forming native eIF4G center dot mRNA center dot PABP complexes. In vitro experiments confirm the role of RNA1 in stabilizing eIF4G-mRNA association, and further indicate that RNA1 and Box1 promote PABP binding, in addition to RNA binding, by the eIF4G1 NTD. Our findings indicate that PABP-eIF4G association is only one of several interactions that stabilize eIF4F center dot mRNA complexes, and emphasize that closed-loop mRNP formation via PABP-eIF4G interaction is non-essential in vivo. Interestingly, two other RNA-binding regions in eIF4G1 have critical functions downstream of eIF4F center dot mRNA assembly. The EMBO Journal (2011) 30, 302-316. doi:10.1038/emboj.2010.312; Published online 7 December 2010