抄録
Escherichia coli mutants which lack defence systems against such active oxygen forms as OxyR (ΔoxyR), 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 (NaN3) during irradiation.
UV-A induces lipid peroxidation in the ΔoxyR mutant, which is suppressed by NaN3. These results suggest that UV-A generates 1O2 or the hydroxyl radical to produce lipid peroxides intracellularly in the ΔoxyR mutant and that O2- stress may be generated in the sodAB mutant after 8 hr of exposure to UV-A. The sensitivities of such DNA repair-deficient mutants as recAind- 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 NaN3 during irradiation. We conclude that NaN3 protects these mutant cells from oxygen-dependent UV-A lethality.
