Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, United States.
Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, United States.
Elife. 2021 Aug 12;10:e70619. doi: 10.7554/eLife.70619.
-methylation of G37 is required for a subset of tRNAs to maintain the translational reading-frame. While loss of mG37 increases ribosomal +1 frameshifting, whether it incurs additional translational defects is unknown. Here, we address this question by applying ribosome profiling to gain a genome-wide view of the effects of mG37 deficiency on protein synthesis. Using as a model, we show that mG37 deficiency induces ribosome stalling at codons that are normally translated by mG37-containing tRNAs. Stalling occurs during decoding of affected codons at the ribosomal A site, indicating a distinct mechanism than that of +1 frameshifting, which occurs after the affected codons leave the A site. Enzyme- and cell-based assays show that mG37 deficiency reduces tRNA aminoacylation and in some cases peptide-bond formation. We observe changes of gene expression in mG37 deficiency similar to those in the stringent response that is typically induced by deficiency of amino acids. This work demonstrates a previously unrecognized function of mG37 that emphasizes its role throughout the entire elongation cycle of protein synthesis, providing new insight into its essentiality for bacterial growth and survival.
mG37 的甲基化对于一组 tRNA 维持翻译读框是必需的。虽然 mG37 的缺失会增加核糖体 +1 移码，但它是否会导致额外的翻译缺陷尚不清楚。在这里，我们通过核糖体图谱应用来解决这个问题，从而获得 mG37 缺乏对蛋白质合成影响的全基因组视图。我们以 作为模型，表明 mG37 缺乏会诱导核糖体在正常由含有 mG37 的 tRNA 翻译的密码子处停顿。停顿发生在受影响的密码子在核糖体 A 位解码期间，表明这是一种与 +1 移码不同的机制，+1 移码发生在受影响的密码子离开 A 位之后。酶和基于细胞的测定表明，mG37 缺乏会降低 tRNA 的氨酰化，在某些情况下会降低肽键的形成。我们观察到 mG37 缺乏时基因表达的变化与通常由氨基酸缺乏引起的严格反应相似。这项工作证明了 mG37 的一个以前未被认识的功能，强调了它在蛋白质合成的整个延伸循环中的作用，为其对细菌生长和存活的必要性提供了新的见解。
