title: [Effect of B polA1- exrA- and recA-gene mutations on the reparation of single-strand DNA breaks induced by N-nitrosomethylurea].
abstract: The effect of different doses of N-methyl-N-nitrosourea (MNU) on a viability of bacterial cells with different defects in the systems of repair of UV-damages, and the MNU induction of single-strand DNA breaks (SS) were studied. The kinetics of both processes was investigated. There was a good correlation between the NMU sensitivity of bacterial cells and the number of SS in their DNAs. The most sensitive were the cells defective in DNA polymerase I. The optimal conditions for DNA repair in the strains under investigation were established. 90% of MNU-induced SS are repaired by DNA polymerase I and do not depend on protein synthesis. On the other hand, the exrA and recA dependent ways of SS repair depend on protein synthesis. The existence of an inducible recAexrA-dependent repair system of NMU-induced lesions in bacterial DNA is proposed.
mesh_terms: D004260:DNA Repair / Q000187:drug effects*; D004269:DNA, Bacterial / Q000235:genetics*; D004277:DNA, Single-Stranded / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D005796:Genes / Q000187:drug effects*; D005838:Genotype; D008770:Methylnitrosourea / Q000494:pharmacology*; D009154:Mutation / Q000187:drug effects*; D009607:Nitrosourea Compounds / Q000494:pharmacology*
chemical_list: D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D009607:Nitrosourea Compounds; D008770:Methylnitrosourea
vernacular_title: Vliianie mutatsiĭ B polA1-, exrA- i recA-genakh na reparatsiiu odnotiazhevykh razryvov DNK, indutsirovannykh N-nitrozometilmochevinoĭ.