Hydrogen peroxide effects in Escherichia coli cells.

Asad, Nasser Ribeiro; Asad, L.M.B.O.; Silva, A. B.; Felzenszwalb, Israel; Leitão, Álvaro C.

doi:10.18388/abp.1998_4261

Cited by 25 publications

(10 citation statements)

References 19 publications

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“…3B), i.e., the level of DNA damage from this peroxide treatment was not sufficient to generate the SOS-dependent signal for activation of RtcR, expression of rsr, rtcB, and rtcA was measured by qRT-PCR after a 20 min treatment with 7 mM H 2 O 2 for WT, ΔrtcR, and ΔrpoN strains. This higher concentration of H 2 O 2 has been shown to result in increased expression of SOS response genes (59). Following treatment with 7 mM H 2 O 2 , transcript levels for rsr, rtcB and rtcA increased in the WT strain by 41-, 11-and 7.2-fold, respectively (P values of 0.02, 0.06, and 0.03, respectively) ( Fig.…”

Section: Resultsmentioning

confidence: 82%

Genotoxic, Metabolic, and Oxidative Stresses Regulate the RNA Repair Operon of Salmonella enterica Serovar Typhimurium

et al. 2018

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The σ regulon in serovar Typhimurium includes a predicted RNA repair operon encoding homologs of the metazoan Ro60 protein (Rsr), Y RNAs (YrlBA), RNA ligase (RtcB), and RNA 3'-phosphate cyclase (RtcA). Transcription from σ-dependent promoters requires that a cognate bacterial enhancer binding protein (bEBP) be activated by a specific environmental or cellular signal; the cognate bEBP for the σ-dependent promoter of the operon is RtcR. To identify conditions that generate the signal for RtcR activation in Typhimurium, transcription of the RNA repair operon was assayed under multiple stress conditions that result in nucleic acid damage. RtcR-dependent transcription was highly induced by the nucleic acid cross-linking agents mitomycin C (MMC) and cisplatin, and this activation was dependent on RecA. Deletion of or resulted in decreased cell viability relative to that of the wild type following treatment with MMC. Oxidative stress from peroxide exposure also induced RtcR-dependent transcription of the operon. Nitrogen limitation resulted in RtcR-independent increased expression of the operon; the effect of nitrogen limitation required NtrC. The adjacent toxin-antitoxin module, , was cotranscribed with the RNA repair operon but was not required for RtcR activation, although YafQ endoribonuclease activated RtcR-dependent transcription. Stress conditions shown to induce expression the RNA repair operon of () did not stimulate expression of the Typhimurium RNA repair operon. Similarly, MMC did not induce expression of the operon, although when expressed in Typhimurium, RtcR responds effectively to the unknown signal(s) generated there by MMC exposure. Homologs of the metazoan RNA repair enzymes RtcB and RtcA occur widely in eubacteria, suggesting a selective advantage. Although the enzymatic activities of the eubacterial RtcB and RtcA have been well characterized, the physiological roles remain largely unresolved. Here we report stress responses that activate expression of the σ-dependent RNA repair operon () of Typhimurium and demonstrate that expression of the operon impacts cell survival under MMC-induced stress. Characterization of the requirements for activation of this tightly regulated operon provides clues to the possible functions of operon components, enhancing our understanding of how this human pathogen copes with environmental stressors.

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Section: Resultsmentioning

confidence: 82%

Genotoxic, Metabolic, and Oxidative Stresses Regulate the RNA Repair Operon of Salmonella enterica Serovar Typhimurium

et al. 2018

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“…Induction of heat shock proteins may be necessary to process denatured or misfolded proteins. Intriguingly, no oxidative stress genes, such as Fe-superoxide dismutase (SodB) and genes in the SOS pathway ( e.g ., RecA, RpoD, RpoH, LexA, SsB, UmuC and UmuD) [ 39 ], were induced when iron was repleted. This is surprising since the excess of external iron is expected to provoke oxidative stress.…”

Section: Discussionmentioning

confidence: 99%

Snapshot of iron response in Shewanella oneidensis by gene network reconstruction

et al. 2009

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Background: Iron homeostasis of Shewanella oneidensis, a γ-proteobacterium possessing high iron content, is regulated by a global transcription factor Fur. However, knowledge is incomplete about other biological pathways that respond to changes in iron concentration, as well as details of the responses. In this work, we integrate physiological, transcriptomics and genetic approaches to delineate the iron response of S. oneidensis.

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“…A similar effect was observed on cell growth. For comparison, cell survival of E. coli reached 10% after 20 min of exposure to 20 mM H 2 O 2 ( Asad et al, 1998 ). H. salinarum cell survival and growth in the face of decreases more gradually, with 20–30% loss of survival occurring at approximately 4 mM paraquat, a compound that generates during metabolism ( Kaur et al, 2010 ).…”

Section: Photoprotectionmentioning

confidence: 99%

DNA Repair and Photoprotection: Mechanisms of Overcoming Environmental Ultraviolet Radiation Exposure in Halophilic Archaea

Jones

Baxter

2017

Front. Microbiol.

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Halophilic archaea push the limits of life at several extremes. In particular, they are noted for their biochemical strategies in dealing with osmotic stress, low water activity and cycles of desiccation in their hypersaline environments. Another feature common to their habitats is intense ultraviolet (UV) radiation, which is a challenge that microorganisms must overcome. The consequences of high UV exposure include DNA lesions arising directly from bond rearrangement of adjacent bipyrimidines, or indirectly from oxidative damage, which may ultimately result in mutation and cell death. As such, these microorganisms have evolved a number of strategies to navigate the threat of DNA damage, which we differentiate into two categories: DNA repair and photoprotection. Photoprotection encompasses damage avoidance strategies that serve as a “first line of defense,” and in halophilic archaea include pigmentation by carotenoids, mechanisms of oxidative damage avoidance, polyploidy, and genomic signatures that make DNA less susceptible to photodamage. Photolesions that do arise are addressed by a number of DNA repair mechanisms that halophilic archaea efficiently utilize, which include photoreactivation, nucleotide excision repair, base excision repair, and homologous recombination. This review seeks to place DNA damage, repair, and photoprotection in the context of halophilic archaea and the solar radiation of their hypersaline environments. We also provide new insight into the breadth of strategies and how they may work together to produce remarkable UV-resistance for these microorganisms.

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Hydrogen peroxide effects in Escherichia coli cells.

Cited by 25 publications

References 19 publications

Genotoxic, Metabolic, and Oxidative Stresses Regulate the RNA Repair Operon of Salmonella enterica Serovar Typhimurium

Genotoxic, Metabolic, and Oxidative Stresses Regulate the RNA Repair Operon of Salmonella enterica Serovar Typhimurium

Snapshot of iron response in Shewanella oneidensis by gene network reconstruction

DNA Repair and Photoprotection: Mechanisms of Overcoming Environmental Ultraviolet Radiation Exposure in Halophilic Archaea

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