MUTAGENIC ACTION OF OXIDATIVE AGENTS ON THE HEAT-INDUCIBLE LAMBDA-CI857 PROPHAGE - INFLUENCE OF THE OXIDATIVE STRESS SYSTEM

The lethal and mutagenic effects of hydrogen peroxide H2O (2 - 20 mM), cumene hydroperoxide (0.2- 2.0 mM), and potassium permanganate KMnO4 (0.25 - 1.0 mM) on the heat-inducible lambda cI857 prophage were studi ed under conditions of heat-induction immediately after the mutagenic treatment of lysogenic cells of Escherichia coil oxyR(+) or oxyR Delta 3. Within the range of the doses used, these agents decreased prophag e survival by 3 - 5 orders of magnitude and increased mutation frequen cy by up to 0.2% under the action of hydrogen peroxide and cumene hydr operoxide, and up to 1.5% in the case of KMnO4 (in oxyR(+) cells). In the absence of the inducible OxyR system of oxidative stress, both let hal-and mutagenic effects of H2O were enhanced. The oxyR Delta 3 mutat ion increased lethal and mutagenic effects of cumene hydroperoxide and KMnO4 only at the highest concentrations used. Apparently, the OxyR s ystem does not repair lesions induced by oxidative agents, but only pr events their formation.