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DNA Repair and Mutagenesis

DNA Repair and Mutagenesis. Main sites of modification of DNA bases by methylating agents.

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DNA Repair and Mutagenesis

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  1. DNA Repair and Mutagenesis

  2. Main sites of modification of DNA bases by methylating agents. The arrow sizes reflect the relative yields of the different methylated products. Atoms or groups involved in Watson–Crick hydrogen bonding are shown in red. Bases methylated at positions indicated by the black arrows are processed primarily by AlkA; those methylated at sites marked with blue arrows are addressed by O6-methylguanine DNA methyltransferase, and those methylated at positions marked with the green arrows are processed by AlkB

  3. AlkB-mediated demethylation of N3-methyladenine and N1-methylcytosine. The methyl groups are converted to hydroxymethyl moieties, which are spontaneously lost in the form of formaldehyde to regenerate the unmodified bases (the aberrant methyl groups and their oxidation products are shown in red). Note that the cofactors (blue) are consumed during the reaction in stoichiometric amount

  4. E. coli that are unable to remove DNA lesions are sensitive to UV irradiation UV dose J/m2 0 5 10 20 40 80 120 WTuvrA uvrB uvrC

  5. People that are unable to remove DNA lesions are also sensitive to UV irradiation Photo taken from Friedberg, EC., Walker GC., Siede, W (1995) in DNA Repair and Mutagenesis (ASM Press, Washington DC)

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