Characterization and Quantitation of DNA Strand Breaks Requiring recA-Dependent Repair in X-Irradiated Escherichia coli

1986 ◽  
Vol 105 (2) ◽  
pp. 180 ◽  
Author(s):  
Neil J. Sargentini ◽  
Kendric C. Smith
Keyword(s):  
Escherichia Coli ◽  
Dna Strand Breaks ◽  
Strand Breaks ◽  
Dna Strand

scholarly journals Repair of DNA Lesions Induced by Hydrogen Peroxide in the Presence of Iron Chelators in Escherichia coli: Participation of Endonuclease IV and Fpg

2000 ◽  
Vol 182 (7) ◽  
pp. 1964-1968 ◽  
Author(s):  
Rodrigo S. Galhardo ◽  
Carlos E. B. Almeida ◽  
Alvaro C. Leitão ◽  
Januário B. Cabral-Neto
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Gene Product ◽  
Double Mutant ◽  
Dna Strand Breaks ◽  
Dna Lesions ◽  
Iron Chelators ◽  
Exonuclease Iii ◽  
Strand Breaks ◽  
Dna Strand

ABSTRACT In Escherichia coli, the repair of lethal DNA damage induced by H2O2 requires exonuclease III, thexthA gene product. Here, we report that both endonuclease IV (the nfo gene product) and exonuclease III can mediate the repair of lesions induced by H2O2 under low-iron conditions. Neither the xthA nor thenfo mutants was sensitive to H2O2in the presence of iron chelators, while the xthA nfodouble mutant was significantly sensitive to this treatment, suggesting that both exonuclease III and endonuclease IV can mediate the repair of DNA lesions formed under such conditions. Sedimentation studies in alkaline sucrose gradients also demonstrated that both xthAand nfo mutants, but not the xthA nfo double mutant, can carry out complete repair of DNA strand breaks and alkali-labile bonds generated by H2O2 under low-iron conditions. We also found indications that the formation of substrates for exonuclease III and endonuclease IV is mediated by the Fpg DNA glycosylase, as suggested by experiments in which thefpg mutation increased the level of cell survival, as well as repair of DNA strand breaks, in an AP endonuclease-null background.

scholarly journals No genotoxicity is detectable for Escherichia coli strain Nissle 1917 by standard in vitro and in vivo tests

2020 ◽  
Vol 10 (1) ◽  
pp. 11-19
Author(s):  
Silke Dubbert ◽  
Birgit Klinkert ◽  
Michael Schimiczek ◽  
Trudy M. Wassenaar ◽  
Rudolf von Bünau
Keyword(s):  
Escherichia Coli ◽  
Ames Test ◽  
Mutagenic Activity ◽  
Dna Strand Breaks ◽  
Coli Strain ◽  
Strand Breaks ◽  
Genotoxic Potential ◽  
Dna Strand

Probiotic Escherichia coli strain Nissle 1917 (EcN) has a long history of safe use. However, the recently discovered presence of a pks locus in its genome presumably producing colibactin has questioned its safety, as colibactin has been implicated in genotoxicity. Here, we assess the genotoxic potential of EcN. Metabolic products were tested in vitro by the Ames test, a mutagenicity assay developed to detect point mutation-inducing activity. Live EcN were tested by an adapted Ames test. Neither the standard nor the adapted Ames test resulted in increased numbers of revertant colonies, indicating that EcN metabolites or viable cells lacked mutagenic activity. The in vivo Mammalian Alkaline Comet Assay (the gold standard for detecting DNA-strand breaks) was used to determine potentially induced DNA-strand breaks in cells of the gastro-intestinal tract of rats orally administered with viable EcN. Bacteria were given at 109–1011 colony forming units (CFU) per animal by oral gavage on 2 consecutive days and daily for a period of 28 days to 5 rats per group. No significant differences compared to negative controls were found. These results demonstrate that EcN does not induce DNA-strand breaks and does not have any detectable genotoxic potential in the test animals.

scholarly journals Alkaline gel electrophoresis assay to detect DNA strand breaks and repair mechanisms in Escherichia coli

2008 ◽  
Vol 51 (spe) ◽  
pp. 121-126 ◽  
Author(s):  
José Carlos Pelielo de Mattos ◽  
Ellen Serri da Motta ◽  
Márcia Betania Nunes de Oliveira ◽  
Flávio José da Silva Dantas ◽  
Adriano Caldeira de Araujo
Keyword(s):  
Escherichia Coli ◽  
Gel Electrophoresis ◽  
Excision Repair ◽  
Dna Strand Breaks ◽  
Strand Breaks ◽  
Cellular Targets ◽  
E Coli ◽  
Repair Mechanisms ◽  
Base Excision ◽  
Dna Strand

Reactive oxygen species (ROS) can induce lesions in different cellular targets, including DNA. Stannous chloride (SnCl2) is a ROS generator, leading to lethality in Escherichia coli (E. coli), with the base excision repair (BER) mechanism playing a role in this process. Many techniques have been developed to detect genotoxicity, as comet assay, in eukaryotic cells, and plasmid DNA agarose gel electrophoresis. In this study, an adaptation of the alkaline gel electrophoresis method was carried out to ascertain the induction of strand breaks by SnCl2 in bacterial DNA, from E. coli BER mutants, and its repair pathway. Results obtained show that SnCl2 was able to induce DNA strand breaks in all strains tested. Moreover, endonuclease IV and exonuclease III play a role in DNA repair. On the whole, data has shown that the alkaline gel electrophoresis assay could be used both for studying DNA strand breaks induction and for associated repair mechanisms.

Escherichia coli radC Is Deficient in the recA-Dependent Repair of X-Ray-Induced DNA Strand Breaks

1986 ◽  
Vol 106 (2) ◽  
pp. 166 ◽  
Author(s):  
Israel Felzenszwalb ◽  
Neil J. Sargentini ◽  
Kendric C. Smith
Keyword(s):  
Escherichia Coli ◽  
Dna Strand Breaks ◽  
Strand Breaks ◽  
X Ray ◽  
Dna Strand
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