title: Repair and recombination of nonreplicating UV-irradiated phage DNA in E. coli III. Enhancement of excision repair in UV-treated bacteria.
abstract: The question of whether induction of the SOS response in Escherichia coli increases the efficiency of excision repair was addressed by measuring repair of UV-damaged nonreplicating lambda phage DNA in previously irradiated bacteria. Prior UV irradiation of lex+ bacteria enhanced both the rate of regeneration of infective phage DNA (about 10-fold) and the rate of cyclobutane dimer removal early in repressed infections. Indirect induction of SOS-regulated repair activities by the nonreplicating irradiated phage DNA itself seemed negligible. Prior bacterial irradiation reduced the frequency of recombination (loss of a tandem chromosomal duplication) of nonreplicating UV-irradiated DNA. In this respect UV-stimulated recombination of nonreplicating DNA differs from RecF-dependent recombination processes that are stimulated by increased SOS expression. Surprisingly, prior UV irradiation of lexA3 bacteria caused a small but reproducible increase in the regeneration of infective phage DNA.
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D010582:Bacteriophage lambda / Q000235:genetics / Q000528:radiation effects*; D004260:DNA Repair / Q000528:radiation effects*; D004261:DNA Replication; D004279:DNA, Viral / Q000235:genetics / Q000528:radiation effects; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D005798:Genes, Bacterial; D007700:Kinetics; D009154:Mutation; D011995:Recombination, Genetic / Q000528:radiation effects*; D012697:Serine Endopeptidases; D014466:Ultraviolet Rays; D000099160:LexA Repressor Protein
chemical_list: D001426:Bacterial Proteins; D004279:DNA, Viral; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein