Schmidt W, Arnold H H, Kersten H
Nucleic Acids Res. 1975 Jul;2(7):1043-51. doi: 10.1093/nar/2.7.1043.
Ribothymidine (m5u) in tRNAs of M. lysodeikticus is not derived from methionine. The results indicate that as in tRNAs of B. subtilis a tetrahydrofolate derivative is involved in the formation of m5U, whereas methionine serves as precursor in the biosynthesis of m7G, m1A and m6A. Ribothymidine also occurs in 23S rRNA of B. subtilis and M. lysodeikticus. Approximately 2-3 moles of m5U residues were found per mole of 23S rRNA. In contrast to m5U residues present in tRNAs of B. subtilis and M. lysodeikticus, ribothymidine in 23S rRNA of these organisms and of E. coli is synthesized via S-adenosylmethionine. m6A and m1G, present in E. coli rRNAs, were not detected in rRNAs of (methyl-14C) methionine labeled B. subtilis and M. lysodeikticus.
溶壁微球菌tRNA中的核糖胸腺嘧啶核苷（m5U）并非源自甲硫氨酸。结果表明，与枯草芽孢杆菌的tRNA情况一样，一种四氢叶酸衍生物参与了m5U的形成，而甲硫氨酸是m7G、m1A和m6A生物合成的前体。核糖胸腺嘧啶核苷也存在于枯草芽孢杆菌和溶壁微球菌的23S rRNA中。每摩尔23S rRNA中大约发现2 - 3摩尔的m5U残基。与枯草芽孢杆菌和溶壁微球菌tRNA中存在的m5U残基不同，这些生物体以及大肠杆菌23S rRNA中的核糖胸腺嘧啶核苷是通过S - 腺苷甲硫氨酸合成的。在以（甲基 - 14C）甲硫氨酸标记的枯草芽孢杆菌和溶壁微球菌的rRNA中未检测到大肠杆菌rRNA中存在的m6A和m1G。
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