title: [Repair of the interstrand cross links in DNA: role of restriction system "K"].
abstract: The interstrand cross links formed in the DNA after psoralenplus light treatment of bacteria E. coli K12 and bacteriophage lambda are repaired by the restriction and modification system "K." Strain E. coli C, which does not have the restriction and modification system is 2 times more sensitive to psoralen plus light treatment, than the wild type E. coli K12. But these strains are equally sensitive to inactivation by UV-light (254 nm). By studing the sedimentation of bacterial DNA in alkaline sucrose it was found that cells of E. coli C are deficient in filling of gaps, appearing in parental DNA after enzymatic excision of the "arms" of cross links. In experiments with bacteriophage lambda (W-reactivation, prophage-reactivation), treated by psoralen plus light, it was shown that E. coli C and mutants of E. coli K12 rk-mk+/- are deficient in non-recombination lexA-dependent repair of cross links. The function of restriction and recognition of restriction and modification system are essential for repair of cross links. It is suggested that the restriction and modification system "K" acts either as a regulatory protein or as a protector of single-stranded regions of DNA against nuclease attack.
mesh_terms: D003090:Coliphages / Q000378:metabolism / Q000528:radiation effects; D004260:DNA Repair; D004262:DNA Restriction Enzymes / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism / Q000528:radiation effects; D004279:DNA, Viral / Q000378:metabolism / Q000528:radiation effects; D004926:Escherichia coli / Q000378:metabolism* / Q000528:radiation effects; D011564:Furocoumarins / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: D004269:DNA, Bacterial; D004279:DNA, Viral; D011564:Furocoumarins; D004262:DNA Restriction Enzymes
vernacular_title: Reparatsiia mezhnitevykh kovalentnykh sshivok i DNK: rol' sistemy restriktsii K.