mRNA- and factor-driven dynamic variability controls eIF4F-cap recognition for translation initiation.
mRNA- and factor-driven dynamic variability controls eIF4F-cap recognition for translation initiation.
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DOI：
10.1093/nar/gkac631
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发表时间：
2022-08-12
影响因子：
14.9
通讯作者：
O'Leary, Sean E.
中科院分区：
文献类型：
--
作者：
Cetin, Burak;O'Leary, Sean E.
eIF4F对mRNA 5 '帽的识别是真核生物翻译控制的关键因素。长期以来，人们一直认为eIF4F - mrna相互作用的动力学差异可以介导mrna之间的翻译效率差异，最近的转录组研究揭示了eIF4F与差异翻译mrna相互作用的显著异质性。然而，详细的动力学信息只存在于eIF4F与短模型rna的相互作用中。我们开发并应用了单分子荧光方法来直接观察酿酒酵母eIF4F亚基与全长聚腺苷化mrna的实时相互作用。我们发现eIF4E-mRNA的关联率与mRNA长度呈线性反相关。eIF4G-mRNA的相互作用加速了eIF4E-mRNA与mRNA长度成比例的关联，eIF4A不依赖于eif4f的活性也是如此，尽管帽端-近端二级结构在确定最终的关联率方面仍然起着重要作用。eIF4F-mRNA的相互作用仍然以eIF4G的作用为主，但不同mrna在不同程度上受到eIF4A和ATP的调节。我们还发现，eif4a催化的ATP水解在初始eIF4F•mRNA复合物形成后将eIF4E，以及可能的eIF4E•eIF4G从mRNA中挤出，这提示了一种为核糖体募集准备mRNA 5 '端的机制。我们的研究结果支持mrna特异性、因子驱动的eIF4F关联率在动态控制翻译中的作用。
mRNA 5′ cap recognition by eIF4F is a key element of eukaryotic translational control. Kinetic differences in eIF4F–mRNA interactions have long been proposed to mediate translation-efficiency differences between mRNAs, and recent transcriptome-wide studies have revealed significant heterogeneity in eIF4F engagement with differentially-translated mRNAs. However, detailed kinetic information exists only for eIF4F interactions with short model RNAs. We developed and applied single-molecule fluorescence approaches to directly observe real-time Saccharomyces cerevisiae eIF4F subunit interactions with full-length polyadenylated mRNAs. We found that eIF4E–mRNA association rates linearly anticorrelate with mRNA length. eIF4G–mRNA interaction accelerates eIF4E–mRNA association in proportion to mRNA length, as does an eIF4F-independent activity of eIF4A, though cap-proximal secondary structure still plays an important role in defining the final association rates. eIF4F–mRNA interactions remained dominated by effects of eIF4G, but were modulated to different extents for different mRNAs by the presence of eIF4A and ATP. We also found that eIF4A-catalyzed ATP hydrolysis ejects eIF4E, and likely eIF4E•eIF4G from the mRNA after initial eIF4F•mRNA complex formation, suggesting a mechanism to prepare the mRNA 5′ end for ribosome recruitment. Our results support a role for mRNA-specific, factor-driven eIF4F association rates in kinetically controlling translation.
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