Archaeal DNA uracil repair via direct strand incision: A minimal system reconstituted from purified components
| Autor: | Lars Schomacher, Hans-Joachim Fritz, Elena Ciirdaeva, K. Anke Schürer, Paul McDermott, Wilfried Kramer, James P. J. Chong |
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| Rok vydání: | 2010 |
| Předmět: |
Methanobacteriaceae
DNA Ligases DNA Repair DNA repair Archaeal Proteins Biology Models Biological Biochemistry Homology directed repair DNA Ligase ATP 03 medical and health sciences Uracil Uracil-DNA Glycosidase Molecular Biology 030304 developmental biology chemistry.chemical_classification 0303 health sciences DNA ligase 030302 biochemistry & molecular biology Cell Biology Base excision repair Very short patch repair DNA Archaeal chemistry DNA glycosylase Uracil-DNA glycosylase Nucleotide excision repair |
| Zdroj: | DNA Repair. 9:438-447 |
| ISSN: | 1568-7864 |
| DOI: | 10.1016/j.dnarep.2010.01.004 |
| Popis: | Hydrolytic deamination of DNA cytosine residues results in U/G mispairs, pre-mutagenic lesions threatening long-term genetic stability. Hence, DNA uracil repair is ubiquitous throughout all extant life forms and base excision repair, triggered by a uracil DNA glycosylase (UDG), is the mechanistic paradigm adopted, as it seems, by all bacteria and eukaryotes and a large fraction of archaea. However, members of the UDG superfamily of enzymes are absent from the extremely thermophilic archaeon Methanothermobacter thermautotrophicus ΔH. This organism, as a hitherto unique case, initiates repair by direct strand incision next to the DNA-U residue, a reaction catalyzed by the DNA uridine endonuclease Mth212, an ExoIII homologue. To elucidate the detailed mechanism, in particular to identify the molecular partners contributing to this repair process, we reconstituted DNA uracil repair in vitro from only four purified enzymes of M. thermautotrophicus ΔH. After incision at the 5′-side of a 2′-d-uridine residue by Mth212 DNA polymerase B (mthPolB) is able to take over the 3′-OH terminus and carry out repair synthesis generating a 5′-flap structure that is resolved by mthFEN, a 5′-flap endonuclease. Finally, DNA ligase seals the resulting nick. This defines mechanism and minimal enzymatic requirements of DNA-U repair in this organism. |
| Databáze: | OpenAIRE |
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