SOS induction in Escherichia coli by infection with mutant filamentous phage that are defective in initiation of complementary-strand DNA synthesis.
We report that the SOS response is induced in Escherichia coli by infection with mutant filamentous phage that are defective in initiation of the complementary (minus)-strand synthesis. One such mutant, R377, which lacks the entire region of the minus-strand origin, failed to synthesize any detectable amount of primer RNA for minus-strand synthesis. In addition, the rate of conversion of parental single-stranded DNA of the mutant to the double-stranded replicative form in infected cells was extremely slow. Upon infection, R377 induced the SOS response in the cell, whereas the wild-type phage did not. The SOS induction was monitored by (i) induction of beta-galactosidase in a strain carrying a dinD::lacZ fusion and (ii) increased levels of RecA protein. In addition, cells infected with R377 formed filaments. Another deletion mutant of the minus-strand origin, M13 delta E101 (M. H. Kim, J. C. Hines, and D. S. Ray, Proc. Natl. Acad. Sci. USA 78:6784-6788, 1981), also induced the SOS response in E. coli. M13Gori101 (D. S. Ray, J. C. Hines, M. H. Kim, R. Imber, and N. Nomura, Gene 18:231-238, 1982), which is a derivative of M13 delta E101 carrying the primase-dependent minus-strand origin of phage G4, did not induce the SOS response. These observations indicate that single-stranded DNA by itself induces the SOS response in vivo.
Higashitani
N
N
Department of Genetics, Graduate University for Advanced Studies, Mishima, Japan.
Higashitani
A
A
Roth
A
A
Horiuchi
K
K
D003090:Coliphages / Q000235:genetics*; D004261:DNA Replication / Q000235:genetics*; D004790:Enzyme Induction; D004926:Escherichia coli / Q000166:cytology / Q000502:physiology*; D007763:Lac Operon; D009154:Mutation; D011938:Rec A Recombinases / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D013014:SOS Response, Genetics / Q000502:physiology*; D014779:Virus Replication / Q000235:genetics*
D011993:Recombinant Fusion Proteins; D011938:Rec A Recombinases