SOS induction of the recA gene by UV-, gamma-irradiation and mitomycin C is mediated by polyamines in Escherichia coli K-12.
Polyamines are involved in a wide range of cellular metabolism. In this study we investigated the effects of polyamines on the SOS induction of the recA gene by exposure to UV-, gamma-irradiation and mitomycin C employing polyamine-deficient mutant and wild type Escherichia. coli strains carrying recA'::'lacZ transcriptional fusion. In the polyamine-deficient mutant, the induction factor of the recA gene by UV-, gamma-irradiation and mitomycin C-treatment are about 3.0-, 2.5- and 4-fold lower, respectively, than those of the wild type. The exogenous addition of polyamines restored the reduced induction of the recA gene to the wild type level. Tri-amine spermidine effectively restored the recA induction to a level similar to the wild type, while being less restored by the di-amine putrescine. The restoration of recA induction by polyamines may be accomplished in a dose- and charge-dependent manner. Our results strongly suggest that polyamines may play an essential role as the SOS inducing mediator following exposure to damaging agents in E. coli and provide important information that tackles an interesting question in how cells respond to chemical and physical stresses.
Kim
I G
IG
Department of Radiation Biology, Environmental Radiation Research Group, Korea Atomic Energy Research Institute, Yusong Taejeon, South Korea. igkim@nanum.kaeri.re.kr
Oh
T J
TJ
D004260:DNA Repair; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D005720:Gamma Rays; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D016685:Mitomycin / Q000494:pharmacology*; D011073:Polyamines / Q000494:pharmacology*; D011938:Rec A Recombinases / Q000235:genetics*; D013014:SOS Response, Genetics / Q000187:drug effects / Q000528:radiation effects; D014466:Ultraviolet Rays
D011073:Polyamines; D016685:Mitomycin; D011938:Rec A Recombinases