The efficiency of translation termination is determined by the nature of the stop codon as well as its context. In eukaryotes, recognition of the A-site stop codon and release of the polypeptide are mediated by release factors eRF1 and eRF3, respectively. Translation termination is modulated by other factors which either directly interact with release factors or bind to the E-site and modulate the activity of the peptidyl transferase center. Previous studies suggested that the Saccharomyces cerevisiae ABCF ATPase New1 is involved in translation termination and/or ribosome recycling, however, the exact function remained unclear. Here, we have applied 5PSeq, single-particle cryo-EM and readthrough reporter assays to provide insight into the biological function of New1. We show that the lack of New1 results in ribosomal stalling at stop codons preceded by a lysine or arginine codon and that the stalling is not defined by the nature of the C-terminal amino acid but rather by the identity of the tRNA isoacceptor in the P-site. Collectively, our results suggest that translation termination is inefficient when ribosomes have specific tRNA isoacceptors in the P-site and that the recruitment of New1 rescues ribosomes at these problematic termination contexts.

中文翻译：

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ABCF ATP 酶 New1 可解决与 P 位点中的特定 tRNAArg 和 tRNALys 同工受体相关的翻译终止缺陷


翻译终止的效率取决于终止密码子的性质及其上下文。在真核生物中，A 位点终止密码子的识别和多肽的释放分别由释放因子 eRF1 和 eRF3 介导。翻译终止受其他因子的调节，这些因子要么直接与释放因子相互作用，要么与 E 位点结合并调节肽基转移酶中心的活性。先前的研究表明，酿酒酵母 ABCF ATP 酶 New1 参与翻译终止和/或核糖体循环，然而，确切的功能仍不清楚。在这里，我们应用了 5PSeq、单颗粒冷冻电镜和通读报告基因分析，以深入了解 New1 的生物学功能。我们表明，缺乏 New1 导致核糖体停滞在赖氨酸或精氨酸密码子前面的终止密码子处，并且停滞不是由 C 末端氨基酸的性质定义的，而是由 P 位点的 tRNA 同工受体的身份定义的。总的来说，我们的结果表明，当核糖体在 P 位点具有特定的 tRNA 同工受体时，翻译终止是低效的，并且 New1 的募集在这些有问题的终止环境中拯救了核糖体。