There has been recent interest in trying to understand the connection between transfer RNA (tRNA) posttranscriptional modifications and changes in-cellular environmental conditions. Here, we report on the identification of the modified nucleoside 5-methylcytidine (m 5 C) in Escherichia coli tRNAs. This modification was determined to be present at position 49 of tRNA Tyr-QUA-II. Moreover, m 5 C levels in this tRNA are significantly elevated under high reactive oxygen specieis (ROS) conditions in E. coli cells. We identified the known ribosomal RNA methyltransferase rsmF as the enzyme responsible for m 5 C synthesis in tRNA and enzyme transcript levels are responsive to elevated levels of ROS in the cell. We further find that changes in m 5 C levels in this tRNA are not specific to Fenton-like reaction conditions elevating ROS, but heat shock can also induce increased modification of tRNA Tyr-QUA-II. Altogether, this work illustrates how cells adapt to changing environmental conditions through variations in tRNA modification profiles.

中文翻译：

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应激诱导的大肠杆菌 tRNA 修饰在可变环中产生 5-甲基胞苷


最近，人们试图了解转移 RNA （tRNA） 转录后修饰与细胞环境条件变化之间的联系。在这里，我们报告了大肠杆菌 tRNA 中修饰核苷 5-甲基胞苷 （m 5 C） 的鉴定。确定这种修饰存在于 tRNA Tyr-QUA-II 的 49 位。此外，在大肠杆菌细胞的高活性氧物种 （ROS） 条件下，该 tRNA 中的 m 5 C 水平显着升高。我们确定了已知的核糖体 RNA 甲基转移酶 rsmF 作为负责 tRNA 中 m 5 C 合成的酶，酶转录水平对细胞中 ROS 水平的升高有反应。我们进一步发现，该 tRNA 中 m 5 C 水平的变化并非特定于升高 ROS 的 Fenton 样反应条件，但热休克也可以诱导 tRNA Tyr-QUA-II 的修饰增加。总而言之，这项工作说明了细胞如何通过 tRNA 修饰谱的变化来适应不断变化的环境条件。