Persson B C, Gustafsson C, Berg D E, Björk G R
Department of Microbiology, University of Umeå, Sweden.
Proc Natl Acad Sci U S A. 1992 May 1;89(9):3995-8. doi: 10.1073/pnas.89.9.3995.
One of the most abundant modified nucleosides in tRNA is 5-methyluridine (m5U or rT, ribothymidine). The enzyme tRNA(m5U54)methyltransferase [S-adenosyl-L-methionine:tRNA (uracil-5-)-methyltransferase, EC 2.1.1.35] (the trmA gene product) catalyzes S-adenosylmethionine-dependent methylation of the uracil in position 54 (T psi C loop) in all Escherichia coli tRNAs to form m5U. Hitherto no modified nucleoside in tRNA has been shown to be essential for growth, although their importance in fine tuning the function of tRNA is well established. In this paper, we show that the structural gene trmA is essential for viability, although the known catalytic activity of the tRNA(m5U54)methyltransferase is not.
转运RNA（tRNA）中最丰富的修饰核苷之一是5-甲基尿苷（m5U或rT，即核糖胸苷）。tRNA（m5U54）甲基转移酶[S-腺苷-L-甲硫氨酸：tRNA（尿嘧啶-5-）-甲基转移酶，EC 2.1.1.35]（trmA基因产物）催化所有大肠杆菌tRNA中第54位（TψC环）尿嘧啶的S-腺苷甲硫氨酸依赖性甲基化，形成m5U。迄今为止，虽然tRNA中的修饰核苷在微调tRNA功能方面的重要性已得到充分证实，但尚未有证据表明tRNA中的修饰核苷对生长至关重要。在本文中，我们表明结构基因trmA对生存能力至关重要，尽管tRNA（m5U54）甲基转移酶的已知催化活性并非如此。
