Methylation damage to RNA induced in vivo in Escherichia coli is repaired by endogenous AlkB as part of the adaptive response
| Autor: | Eva K. Svaasand, Cathrine Broberg Vågbø, Per Arne Aas, Hans E. Krokan |
|---|---|
| Rok vydání: | 2013 |
| Předmět: |
DNA
Bacterial Alkylating Agents DNA Repair DNA repair AlkB Biology medicine.disease_cause Methylation Biochemistry Mixed Function Oxygenases chemistry.chemical_compound Escherichia coli medicine Molecular Biology Post-transcriptional regulation Escherichia coli Proteins RNA Cell Biology RNA repair Methyl Methanesulfonate Adaptation Physiological Molecular biology Kinetics RNA Bacterial chemistry Enzyme Induction biology.protein DNA |
| Zdroj: | DNA Repair. 12:188-195 |
| ISSN: | 1568-7864 |
| DOI: | 10.1016/j.dnarep.2012.11.010 |
| Popis: | Cytotoxic 1-methyladenine (1-meA) and 3-methylcytosine (3-meC) lesions induced in DNA and RNA in vitro and in pre-damaged DNA and RNA bacteriophages in vivo are repaired by the Escherichia coli (E. coli) protein AlkB and a human homolog, ALKBH3. However, it is not known whether endogenous RNA is repaired in vivo by repair proteins present at physiological concentrations. The concept of RNA repair as a biologically relevant process has therefore remained elusive. Here, we demonstrate AlkB-mediated repair of endogenous RNA in vivo by measuring differences in lesion-accumulation in two independent AlkB-proficient and deficient E. coli strains during exposure to methyl methanesulfonate (MMS). Repair was observed both in AlkB-overproducing strains and in the wild-type strains after AlkB induction. RNA repair appeared to be highest in RNA species below 200 nucleotides in size, mainly comprising tRNAs. Strikingly, at least 10-fold more lesions were repaired in RNA than in DNA. This may be a consequence of some 30-fold higher levels of aberrant methylation in RNA than in DNA after exposure to MMS. A high primary kinetic isotope effect (>10) was measured using a deuterated methylated RNA substrate, D3-1me(rA), demonstrating that it is the catalytic step, and not the search step that is rate-limiting. Our results demonstrate that RNA repair by AlkB takes place in endogenous RNA as part of an adaptive response in wild-type E. coli cells. |
| Databáze: | OpenAIRE |
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