scholarly journals Endogenous superoxide is a key effector of the oxygen sensitivity of a model obligate anaerobe

2018 ◽  
Vol 115 (14) ◽  
pp. E3266-E3275 ◽  
Author(s):  
Zheng Lu ◽  
Ramakrishnan Sethu ◽  
James A. Imlay
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Major Element ◽  
Oxygen Sensitivity ◽  
Obligate Anaerobe ◽  
Human Gastrointestinal Tract ◽  
E Coli ◽  
Mononuclear Iron ◽  
Enzyme Families ◽  
Species Production

It has been unclear whether superoxide and/or hydrogen peroxide play important roles in the phenomenon of obligate anaerobiosis. This question was explored usingBacteroides thetaiotaomicron, a major fermentative bacterium in the human gastrointestinal tract. Aeration inactivated two enzyme families—[4Fe-4S] dehydratases and nonredox mononuclear iron enzymes—whose homologs, in contrast, remain active in aerobicEscherichia coli. Inactivation-rate measurements of one such enzyme,B. thetaiotaomicronfumarase, showed that it is no more intrinsically sensitive to oxidants than is anE. colifumarase. Indeed, when theE. colienzymes were expressed inB. thetaiotaomicron, they no longer could tolerate aeration; conversely, theB. thetaiotaomicronenzymes maintained full activity when expressed in aerobicE. coli. Thus, the aerobic inactivation of theB. thetaiotaomicronenzymes is a feature of their intracellular environment rather than of the enzymes themselves.B. thetaiotaomicronpossesses superoxide dismutase and peroxidases, and it can repair damaged enzymes. However, measurements confirmed that the rate of reactive oxygen species production inside aeratedB. thetaiotaomicronis far higher than inE. coli. Analysis of the damaged enzymes recovered from aeratedB. thetaiotaomicronsuggested that they had been inactivated by superoxide rather than by hydrogen peroxide. Accordingly, overproduction of superoxide dismutase substantially protected the enzymes from aeration. We conclude that when this anaerobe encounters oxygen, its internal superoxide levels rise high enough to inactivate key catabolic and biosynthetic enzymes. Superoxide thus comprises a major element of the oxygen sensitivity of this anaerobe. The extent to which molecular oxygen exerts additional direct effects remains to be determined.

Further investigation of the mechanism of Vitreoscilla hemoglobin (VHb) protection from oxidative stress in Escherichia coli

Biologia ◽  
2011 ◽  
Vol 66 (5) ◽  
Author(s):  
Meltem Akbas ◽  
Tugrul Doruk ◽  
Serhat Ozdemir ◽  
Benjamin Stark
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Stationary Phase ◽  
Exponential Phase ◽  
Vitreoscilla Hemoglobin ◽  
Sod Activity ◽  
E Coli ◽  
Hydrogen Peroxide Treatment

AbstractIn Escherichia coli, Vitreoscilla hemoglobin (VHb) protects against oxidative stress, perhaps, in part, by oxidizing OxyR. Here this protection, specifically VHb-associated effects on superoxide dismutase (SOD) and catalase levels, was examined. Exponential or stationary phase cultures of SOD+ or SOD− E. coli strains with or without VHb and oxyR antisense were treated with 2 mM hydrogen peroxide without sublethal peroxide induction, and compared to untreated control cultures. The hydrogen peroxide treatment was toxic to both SOD+ and SOD− cells, but much more to SOD− cells; expression of VHb in SOD+ strains enhanced this toxicity. In contrast, the presence of VHb was generally associated in the SOD+ background with a modest increase in SOD activity that was not greatly affected by oxyR antisense or peroxide treatment. In both SOD+ and SOD− backgrounds, VHb was associated with higher catalase activity both in the presence and absence of peroxide. Contrary to its stimulatory effects in stationary phase, in exponential phase oxyR antisense generally decreased VHb levels.

Superoxide dismutase activity in root-colonizing pseudomonads

1993 ◽  
Vol 39 (4) ◽  
pp. 420-429 ◽  
Author(s):  
J. Katsuwon ◽  
R. Zdor ◽  
A. J. Anderson
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Superoxide Anion ◽  
Plant Root ◽  
Polyacrylamide Gel Electrophoresis ◽  
Root Surface ◽  
Superoxide Anion Production ◽  
E Coli ◽  
Phosphate Availability ◽  
External Sources

Several saprophytic fluorescent pseudomonads that are aggressive root colonizers express similar specific activities of superoxide dismutase during growth in liquid culture. The pseudomonads have the potential to produce hydrogen peroxide sensitive and hydrogen peroxide insensitive isoforms of superoxide dismutase with distinct mobilities in nondenaturing polyacrylamide gel electrophoresis. Synthesis of the hydrogen peroxide insensitive form is enhanced by limited iron availability, by exposure to Mn2+, and to a lesser extent by external sources of superoxide anion. Unlike Pseudomonas aeruginosa, a root-colonizing strain of Pseudomonas putida did not show regulation of isoform pattern by phosphate availability. A plasmid potentially encoding the pseudomonad hydrogen peroxide sensitive form complemented the superoxide dismutase deficiency in a mutant of Escherichia coli lacking expression of both Fe and Mn genes. Contact between the plant root and pseudomonad or E. coli cells that lack or express superoxide dismutase did not influence superoxide anion production from root surface enzymes. The pseudomonad and the superoxide dismutase deficient and producing E. coli strains survived exposure to the root equally well. Only the hydrogen peroxide sensitive isoform of superoxide dismutase was detected in P. putida cells associated with bean root surfaces.Key words: pseudomonads, activated oxygen, root surface colonization.

Antioxidative Responses of Tobacco Expressing a Bacterial Glutathione Reductase

2003 ◽  
Vol 58 (11-12) ◽  
pp. 843-849 ◽  
Author(s):  
Barbara Lederer ◽  
Peter Böger
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Lipid Peroxidation ◽  
Superoxide Dismutase ◽  
Stress Response ◽  
Glutathione Reductase ◽  
Wild Type ◽  
Transcript Levels ◽  
E Coli ◽  
Violaxanthin Deepoxidase

Abstract Reports on stress response of tobacco expressing a bacterial glutathione reductase (GR) do not agree. To clarify this situation we investigated several parameters using the tobacco BelW3 line and its transformant BelW3gor expressing an E. coli GR. This alteration in the activity of GR led to an ambiguous modification of the antioxidative system. In contrast to the wild type, the transgenic tobacco suffered lipid peroxidation under moderate light intensities, while it was found to be more resistant towards oxidative stress induced by paraquat or hydrogen peroxide. Transcript levels for violaxanthin deepoxidase and cytosolic Cu-Zn-superoxide dismutase were strongly reduced in BelW3gor plants as compared to BelW3.

scholarly journals A novel Keap1 inhibitor iKeap1 activates Nrf2 signaling and ameliorates hydrogen peroxide-induced oxidative injury and apoptosis in osteoblasts

2021 ◽  
Vol 12 (7) ◽  
Author(s):  
Yue-huan Zheng ◽  
Jian-jun Yang ◽  
Pei-jun Tang ◽  
Yuan Zhu ◽  
Zhe Chen ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Nuclear Translocation ◽  
Oxidative Injury ◽  
Potential Effect ◽  
Protein Stabilization ◽  
Human Osteoblasts ◽  
Nrf2 Knockout ◽  
Anti Oxidant ◽  
Species Production ◽  
Nrf2 Protein

AbstractAn ultra-large structure-based virtual screening has discovered iKeap1 as a direct Keap1 inhibitor that can efficiently activate Nrf2 signaling. We here tested its potential effect against hydrogen peroxide (H2O2)-induced oxidative injury in osteoblasts. In primary murine and human osteoblasts, iKeap1 robustly activated Nrf2 signaling at micromole concentrations. iKeap1 disrupted Keap1-Nrf2 association, causing Nrf2 protein stabilization, cytosol accumulation and nuclear translocation in murine and human osteoblasts. The anti-oxidant response elements (ARE) activity and transcription of Nrf2-ARE-dependent genes (including HO1, NQO1 and GCLC) were increased as well. Significantly, iKeap1 pretreatment largely ameliorated H2O2-induced reactive oxygen species production, lipid peroxidation and DNA damage as well as cell apoptosis and programmed necrosis in osteoblasts. Moreover, dexamethasone- and nicotine-induced oxidative injury and apoptosis were alleviated by iKeap1. Importantly, Nrf2 shRNA or CRISPR/Cas9-induced Nrf2 knockout completely abolished iKeap1-induced osteoblast cytoprotection against H2O2. Conversely, CRISPR/Cas9-induced Keap1 knockout induced Nrf2 cascade activation and mimicked iKeap1-induced cytoprotective actions in murine osteoblasts. iKeap1 was ineffective against H2O2 in the Keap1-knockout murine osteoblasts. Collectively, iKeap1 activated Nrf2 signaling cascade to inhibit H2O2-induced oxidative injury and death of osteoblasts.

Effect of Val 73 → Trp Mutation on the Reaction of “Cambialistic” Superoxide Dismutase fromPropionibacterium shermaniiwith Hydrogen Peroxide

1997 ◽  
Vol 345 (1) ◽  
pp. 156-159 ◽  
Author(s):  
R. Gabbianelli ◽  
A. Battistoni ◽  
C. Capo ◽  
F. Polticelli ◽  
G. Rotilio ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase

scholarly journals Cromoglycate and nedocromil enhanced the reactive oxygen species-dependent suppressions with, but not without, dexamethasone in ischaemic and histamine paw oedema of mice

1997 ◽  
Vol 6 (5-6) ◽  
pp. 369-374
Author(s):  
Y. Oyanagui
Keyword(s):  
Reactive Oxygen Species ◽  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Glucocorticoid Receptor ◽  
Low Dose ◽  
Natural Antioxidant ◽  
Target Cells ◽  
Oxygen Species ◽  
Paw Oedema ◽  
Β Carotene

Anti-inflammatory actions of two anti-allergic drugs, alone or with dexamethasone (Dex) were examined in two models, because inflammation is claimed to be important for allergic events, especially for asthma. Cromoglycate and nedocromil were tested in ischaemic- and histamineinduced paw oedema models of mice. These antiallergic drugs (1–100 mg/kg, i.p.) failed to suppress these oedemata, but enhanced the suppressions by a low dose of dexamethasone (0.1 mg/kg, s.c.) at 3–8 h after Dex injection. The mode of effects by anti-allergic drugs resembled that of a natural antioxidant (α-tocopherol, β-carotene etc.), and was different from that of an immunosuppressant like FK506. The enhancing potencies of the two anti-allergic drugs were similar at 6 h after Dex in both oedemata, and were diminished by superoxide dismutase (SOD) or catalase (i.p.). Cycloheximide completely abolished suppressions. Nedocromil, but not cromoglycate, inhibits inflammatory events. Therefore, there are common unknown actions by which the two anti-allergics enhance suppression by Dex. A possible mechanism of this action was supposed to enhance the superoxide and/or hydrogen peroxide-dependent glucocorticoid receptor (GR) signalling in the target cells.

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