Mini-F plasmid-induced SOS signal in Escherichia coli is RecBC dependent.
Dispensable replicons such as F plasmid [95 kilobases (kb)] or its mini-derivatives such as mini-F (9.3 kb) or lambda mini-F efficiently induced cellular SOS genes such as sfiA (sulA) when they were damaged by UV irradiation and then introduced into a recipient bacterium. To generate an SOS signal, UV light-damaged mini-F or mini-F conditional mutants deficient in replication required that the bacterial RecBC enzyme retained some activity different from the nuclease activity that was dispensable. In contrast, UV light-damaged F plasmid produced an SOS signal independently of the activity of the RecBC enzyme and of the expression of the mini-F, -H, and -G proteins. Our findings are consistent with a picture in which the SOS signal is constituted by stretches of single-stranded DNA on a replicon. Moreover, our present data combined with other data previously published lead to the hypothesis that the SOS signal induced by mini-F plasmid is located in trans on the host chromosome, whereas the one generated by UV light-damaged F plasmid is in cis on the transferred DNA.
D002876:Chromosomes, Bacterial / Q000528:radiation effects; D004260:DNA Repair; D004261:DNA Replication / Q000528:radiation effects; D004269:DNA, Bacterial / Q000528:radiation effects; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D043211:Exodeoxyribonuclease V; D005090:Exodeoxyribonucleases / Q000235:genetics*; D005144:F Factor; D005798:Genes, Bacterial; D046911:Macromolecular Substances; D010957:Plasmids; D014466:Ultraviolet Rays
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D005090:Exodeoxyribonucleases; D043211:Exodeoxyribonuclease V; C468322:exodeoxyribonuclease V, E coli