mRNA 5′ cap recognition by eIF4F is a key step in eukaryotic translational control. While different mRNAs respond differently to eIF4F–directed regulation, the molecular basis for this variability remains unclear. We developed single-molecule fluorescence assays to directly observe eIF4F–mRNA interactions. We uncovered a complex interplay of mRNA features with factor activities that differentiates cap recognition between mRNAs. eIF4E–cap association rates are anticorrelated with mRNA length. eIF4A leverages ATP binding to differentially accelerate eIF4E–mRNA association; the extent of this acceleration correlates with translation efficiency in vivo. eIF4G lengthens eIF4E–cap binding to persist on the initiation timescale. The full eIF4F complex discriminates between mRNAs in an ATP-dependent manner. After eIF4F–mRNA binding, eIF4E is ejected from the cap by eIF4A ATP hydrolysis. Our results suggest features throughout mRNA coordinate in controlling cap recognition at the 5ʹ end, and suggest a model for how eIF4F–mRNA dynamics establish mRNA sensitivity to translational control processes.

中文翻译：

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mRNA 和因子驱动的动态变异性控制用于翻译起始的 eIF4F-Cap 识别。

eIF4F 识别 mRNA 5' 帽是真核翻译控制的关键步骤。虽然不同的 mRNA 对 eIF4F 定向调控的反应不同，但这种变异性的分子基础仍不清楚。我们开发了单分子荧光分析来直接观察 eIF4F-mRNA 的相互作用。我们发现了 mRNA 特征与区分 mRNA 之间帽子识别的因子活性之间复杂的相互作用。eIF4E-cap 关联率与 mRNA 长度反相关。eIF4A 利用 ATP 结合来差异加速 eIF4E-mRNA 结合；这种加速的程度与体内翻译效率相关。eIF4G 延长 eIF4E-cap 结合以在起始时间尺度上持续存在。完整的 eIF4F 复合物以 ATP 依赖性方式区分 mRNA。eIF4F-mRNA结合后，eIF4E 通过 eIF4A ATP 水解从帽中弹出。我们的结果表明整个 mRNA 协调的特征在控制 5ʹ 末端的帽识别方面，并提出了一个关于 eIF4F-mRNA 动力学如何建立 mRNA 对翻译控制过程的敏感性的模型。