Post-irradiation DNA degradation in certain repair-deficient E.Coli strains

To make clearer the role of the repair systems in DNA the recA, lexA, recBC- and pol4- mutant cells were subjected to γ-irradiation. It was shown that the cultivation of the cells in nutrient media after irradiation essentially alters the cell recovery. Polyfunctional nature of the RecA protein completely manifests itself and in particular as a protease cleaves sufficiently of λ-repressor in order to defy the prophafe induction. It is believed that the presence of λ-repressor in a host-cell is an additional weight on the recA - lexA - dependent repair and that the additional cleavage of the λ-repressor perturbs and restricts RecA protein to protect DNA gaps. Thus the repair capability of the cell reduces and DNA degradation increases. 24 refs.; 4 figs.; 1 tab