Effect of NaN3 on Oxygen-Dependent Lethality of UV-A in Escherichia coli Mutants Lacking Active Oxygen-Defence and DNA-Repair Systems

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Escherichia coli mutants which lack defence systems against such active oxygen forms as OxyR (△oxyR), superoxide dismutase (SOD) (sodA and sodB) and catalase (katE and katG) are sensitive to UV-A lethality under aerobic conditions, whereas OxyR- and SOD-mutants have resistance under anaerobic conditions and in the presence of sodium azide (NaN_3) during irradiation. UV-A induces lipid peroxidation in the △oxyR mutant, which is suppressed by NaN_3. These results suggest that UV-A generates ^1O_2 or the hydroxyl radical to produce lipid peroxides intracellularly in the △oxyR mutant and that O_2^- stress may be generated in the sodAB mutant after 8hr of exposure to UV-A. The sensitivities of such DNA repair-deficient mutants as recA^<ind> and uvrA to UV-A also were examined and compared. These mutants are sensitive to UV-A lethality under aerobic conditions but show only slight resistance under anaerobic conditions or in the presence of NaN_3 during irradiation.
日本放射線影響学会の論文