Radiolytic signature of Z-DNA

Abstract : Ionizing radiations induce various damages in DNA via the hydroxyl radical OH. generated by the radiolysis of water. We compare here the radiosensitivity of B- and Z-DNA, by using a Z-prone stretch included in a plasmid. In the supercoiled plasmid, the stretch is in the Z-form, whereas it is in the B-form when the plasmid is relaxed. Frank strand breaks (FSB) and alkali-revealed breaks (ARB) were located and quantified using sequencing gel electrophoresis. We show that B- and Z-DNA have the same mean sensitivity towards radiolytic attack, for both FSB and ARB. Nevertheless, the guanine sites are more sensitive, and the cytosine sites less sensitive in Z- than in B-DNA, leading to a characteristic signature of the Z-form. The comparison of experiments with the outcome of a Monte Carlo simulation of OH. radical attack suggests that transfer of initial damage from a guanine base to its attached sugar or the adjacent 3' cytosine is more important in Z-DNA than in B-DNA.
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Laurence Tartier, Veslav Michalik, Melanie Spotheim-Maurizot, A. Rachid Rahmouni, Roland Sabattier, et al.. Radiolytic signature of Z-DNA. Nucleic Acids Research, Oxford University Press, 1994, 22 (25), pp.5565-5570. ⟨10.1093/nar/22.25.5565⟩. ⟨hal-02127214⟩

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