While the centrality of posttranscriptional modifications to RNA biology has long been acknowledged, the function of the vast majority of modified sites remains to be discovered. Illustrative of this, there is not yet a discrete biological role assigned for one of the most highly conserved modifications, 5-methyluridine at position 54 in tRNAs (m 5 U54). Here, we uncover contributions of m 5 U54 to both tRNA maturation and protein synthesis. Our mass spectrometry analyses demonstrate that cells lacking the enzyme that installs m 5 U in the T-loop (TrmA in Escherichia coli , Trm2 in Saccharomyces cerevisiae ) exhibit altered tRNA modification patterns. Furthermore, m 5 U54-deficient tRNAs are desensitized to small molecules that prevent translocation in vitro. This finding is consistent with our observations that relative to wild-type cells, trm2Δ cell growth and transcriptome-wide gene expression are less perturbed by translocation inhibitors. Together our data suggest a model in which m 5 U54 acts as an important modulator of tRNA maturation and translocation of the ribosome during protein synthesis.

中文翻译：

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保守的 5-甲基尿苷 tRNA 修饰调节核糖体易位


虽然转录后修饰对 RNA 生物学的重要性早已被人们所认识，但绝大多数修饰位点的功能仍有待发现。说明这一点的是，对于 tRNA 中 54 位的 5-甲基尿苷（m 5 U54）。在这里，我们揭示了 m 的贡献5 U54 参与 tRNA 成熟和蛋白质合成。我们的质谱分析表明，细胞缺乏安装 m 的酶。 5 T 环路中的 U（TrmA 中大肠杆菌, Trm2 中酿酒酵母）表现出改变的 tRNA 修饰模式。此外，米5 U54 缺陷的 tRNA 对小分子不敏感，可防止体外易位。这一发现与我们的观察结果一致，相对于野生型细胞， trm2Δ细胞生长和转录组范围内的基因表达受易位抑制剂的干扰较小。我们的数据共同提出了一个模型，其中 m 5 U54 在蛋白质合成过程中充当 tRNA 成熟和核糖体易位的重要调节剂。