Mechanism of regulation of 8-hydroxyguanine endonuclease by oxidative stress: roles of FNR, ArcA, and Fur.
We found previously that 8-hydroxyguanine (oh8Gua) endonuclease in E. coli is induced in response to oxidative stress in a fashion similar to the oxidative response of the Mn-superoxide dismutase (MnSOD). In this study, attempts were made to identify the genes involved in the co-regulation of E. coli endonuclease and MnSOD (sodA). oh8Gua nuclease is induced by molecular oxygen and a superoxide radical generator (paraquat) but not by H2O2, suggesting that the regulation of this endonuclease is dependent on SoxRS but independent of OxyR. This enzyme was induced by paraquat in all of the soxRS mutant strains used (soxR-, soxS- and soxRc), whereas glucose-6-phosphate dehydrogenase (a member of the soxRS regulon) showed the expected responses; therefore, this possibility was excluded. The presence of metal chelators in the growth medium caused the induction of this enzyme, and this induction was suppressed by the addition of Fe++. Consistent with this finding, this enzyme was expressed under anaerobiosis in all of the mutant strains of fnr in particular, as well as fur, arcA, and combinations thereof. These findings suggest that the oxidative regulation of oh8Gua endonuclease is under control of fnr, fur, and arcA, where fnr plays a predominant role. The multiple involvement of regulatory genes as well as co-regulation with antioxidant enzyme will enhance the efficiency of cellular growth and survival in the aerobic environment.
Lee
H S
HS
Department of Pharmacology, Seoul National University College of Medicine, Chongno-gu, Seoul, Korea.
Lee
Y S
YS
Kim
H S
HS
Choi
J Y
JY
Hassan
H M
HM
Chung
M H
MH
D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002374:Catalase / Q000096:biosynthesis; D002614:Chelating Agents / Q000494:pharmacology; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D043382:DNA-Formamidopyrimidine Glycosylase; D004790:Enzyme Induction / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D029968:Escherichia coli Proteins; D005609:Free Radicals / Q000378:metabolism; D005798:Genes, Bacterial; D005954:Glucosephosphate Dehydrogenase / Q000096:biosynthesis; D006861:Hydrogen Peroxide / Q000633:toxicity; D007506:Iron-Sulfur Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D009699:N-Glycosyl Hydrolases / Q000096:biosynthesis*; D018384:Oxidative Stress / Q000187:drug effects; D010269:Paraquat / Q000633:toxicity; D012097:Repressor Proteins / Q000235:genetics; D013482:Superoxide Dismutase / Q000096:biosynthesis / Q000378:metabolism
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002614:Chelating Agents; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C060704:FNR protein, E coli; D005609:Free Radicals; D007506:Iron-Sulfur Proteins; D012097:Repressor Proteins; C041610:arcA protein, E coli; C068477:ferric uptake regulating proteins, bacterial; D006861:Hydrogen Peroxide; D005954:Glucosephosphate Dehydrogenase; D002374:Catalase; D013482:Superoxide Dismutase; D009699:N-Glycosyl Hydrolases; D043382:DNA-Formamidopyrimidine Glycosylase; C468610:DNA-formamidopyrimidine glycosylase, E coli; D010269:Paraquat