Ougland Rune, Zhang Chun-Mei, Liiv Aivar, Johansen Rune F, Seeberg Erling, Hou Ya-Ming, Remme Jaanus, Falnes Pål Ø
Centre for Molecular Biology and Neuroscience and Institute of Medical Microbiology, Rikshospitalet University Hospital, NO-0027 Oslo, Norway.
Mol Cell. 2004 Oct 8;16(1):107-16. doi: 10.1016/j.molcel.2004.09.002.
Deleterious 1-methyladenine (1-meA) and 3-methylcytosine (3-meC) lesions are introduced into nucleic acids by methylating agents. It was recently demonstrated that the E. coli AlkB protein and a human homolog, hABH3, can demethylate these lesions both in DNA and RNA. To elucidate the biological significance of the RNA repair, we have tested whether such repair can rescue the function of chemically methylated RNA. We demonstrate that a methylation-induced block in translation of an mRNA can be readily relieved by treatment with AlkB and hABH3 prior to translation. Furthermore, we show that chemical methylation of tRNAPhe inhibits aminoacylation and translation, but that the inhibition can be reversed by AlkB and hABH3. AlkB-mediated repair of 1-meA in tRNA was also observed in E. coli in vivo. Our data demonstrate that AlkB proteins can mediate functional recovery of RNA exposed to methylation damage, supporting the notion that RNA repair is important.
有害的1-甲基腺嘌呤（1-meA）和3-甲基胞嘧啶（3-meC）损伤是由甲基化剂引入核酸中的。最近有研究表明，大肠杆菌的AlkB蛋白及其人类同源物hABH3能够使DNA和RNA中的这些损伤去甲基化。为了阐明RNA修复的生物学意义，我们测试了这种修复是否能够挽救化学甲基化RNA的功能。我们证明，在翻译前用AlkB和hABH3处理，可以很容易地缓解mRNA甲基化诱导的翻译阻断。此外，我们还表明，苯丙氨酸tRNA的化学甲基化会抑制氨酰化和翻译，但AlkB和hABH3可以逆转这种抑制作用。在大肠杆菌体内也观察到了AlkB介导的tRNA中1-meA的修复。我们的数据表明，AlkB蛋白能够介导遭受甲基化损伤的RNA的功能恢复，这支持了RNA修复很重要这一观点。
