scholarly journals ROS Defense Systems and Terminal Oxidases in Bacteria

Antioxidants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 839
Author(s):  
Vitaliy B. Borisov ◽  
Sergey A. Siletsky ◽  
Martina R. Nastasi ◽  
Elena Forte
Keyword(s):  
Defense Mechanisms ◽  
Protective Role ◽  
Superoxide Dismutases ◽  
Oxygen Species ◽  
Ros Scavenging ◽  
Terminal Oxidases ◽  
Defense Systems ◽  
Respiratory Chains ◽  
Scavenging Enzymes

Reactive oxygen species (ROS) comprise the superoxide anion (O2·−), hydrogen peroxide (H2O2), hydroxyl radical (·OH), and singlet oxygen (1O2). ROS can damage a variety of macromolecules, including DNA, RNA, proteins, and lipids, and compromise cell viability. To prevent or reduce ROS-induced oxidative stress, bacteria utilize different ROS defense mechanisms, of which ROS scavenging enzymes, such as superoxide dismutases, catalases, and peroxidases, are the best characterized. Recently, evidence has been accumulating that some of the terminal oxidases in bacterial respiratory chains may also play a protective role against ROS. The present review covers this role of terminal oxidases in light of recent findings.

scholarly journals Nitric Oxide Does Not Inhibit but Is Metabolized by the Cytochrome bcc-aa3 Supercomplex

2020 ◽  
Vol 21 (22) ◽  
pp. 8521 ◽  
Author(s):  
Elena Forte ◽  
Alessandro Giuffrè ◽  
Li-shar Huang ◽  
Edward A. Berry ◽  
Vitaliy B. Borisov
Keyword(s):  
Nitric Oxide ◽  
Active Site ◽  
Protective Role ◽  
Terminal Oxidase ◽  
O2 Consumption ◽  
Turnover Number ◽  
Terminal Oxidases ◽  
Reducing Conditions ◽  
No Consumption

Nitric oxide (NO) is a well-known active site ligand and inhibitor of respiratory terminal oxidases. Here, we investigated the interaction of NO with a purified chimeric bcc-aa3 supercomplex composed of Mycobacterium tuberculosis cytochrome bcc and Mycobacterium smegmatisaa3-type terminal oxidase. Strikingly, we found that the enzyme in turnover with O2 and reductants is resistant to inhibition by the ligand, being able to metabolize NO at 25 °C with an apparent turnover number as high as ≈303 mol NO (mol enzyme)−1 min−1 at 30 µM NO. The rate of NO consumption proved to be proportional to that of O2 consumption, with 2.65 ± 0.19 molecules of NO being consumed per O2 molecule by the mycobacterial bcc-aa3. The enzyme was found to metabolize the ligand even under anaerobic reducing conditions with a turnover number of 2.8 ± 0.5 mol NO (mol enzyme)−1 min−1 at 25 °C and 8.4 µM NO. These results suggest a protective role of mycobacterial bcc-aa3 supercomplexes against NO stress.

scholarly journals The Role of Oxidative Stress in Cardiac Disease: From Physiological Response to Injury Factor

2020 ◽  
Vol 2020 ◽  
pp. 1-29 ◽  
Author(s):  
Rossella D’Oria ◽  
Rossella Schipani ◽  
Anna Leonardini ◽  
Annalisa Natalicchio ◽  
Sebastio Perrini ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Myocardial Injury ◽  
Antioxidant Defense ◽  
Experimental Studies ◽  
Chemical Species ◽  
Oxygen Species ◽  
Molecular Abnormalities ◽  
Defense Systems ◽  
Antioxidant Defense Systems

Reactive oxygen species (ROS) are highly reactive chemical species containing oxygen, controlled by both enzymatic and nonenzymatic antioxidant defense systems. In the heart, ROS play an important role in cell homeostasis, by modulating cell proliferation, differentiation, and excitation-contraction coupling. Oxidative stress occurs when ROS production exceeds the buffering capacity of the antioxidant defense systems, leading to cellular and molecular abnormalities, ultimately resulting in cardiac dysfunction. In this review, we will discuss the physiological sources of ROS in the heart, the mechanisms of oxidative stress-related myocardial injury, and the implications of experimental studies and clinical trials with antioxidant therapies in cardiovascular diseases.

scholarly journals Seed Treatment with Trichoderma longibrachiatum T6 Promotes Wheat Seedling Growth under NaCl Stress Through Activating the Enzymatic and Nonenzymatic Antioxidant Defense Systems

2019 ◽  
Vol 20 (15) ◽  
pp. 3729 ◽  
Author(s):  
Shuwu Zhang ◽  
Bingliang Xu ◽  
Yantai Gan
Keyword(s):  
Salt Stress ◽  
Antioxidant Defense ◽  
Wheat Seedling ◽  
Nacl Stress ◽  
Ros Scavenging ◽  
Wheat Seedlings ◽  
Defense Systems ◽  
Antioxidant Defense Systems ◽  
Scavenging Enzymes ◽  
Different Levels

Salt stress is one of the major abiotic stresses limiting crop growth and productivity worldwide. Species of Trichoderma are widely recognized for their bio-control abilities, but little information is regarding to the ability and mechanisms of their promoting plant growth and enhancing plant tolerance to different levels of salt stress. Hence, we determined (i) the role of Trichoderma longibrachiatum T6 (TL-6) in promoting wheat (Triticum aestivum L.) seed germination and seedling growth under different levels of salt stress, and (ii) the mechanisms responsible for the enhanced tolerance of wheat to salt stress by TL-6. Wheat seeds treated with or without TL-6 were grown under different levels of salt stress in controlled environmental conditions. As such, the TL-6 treatments promoted seed germination and increased the shoot and root weights of wheat seedlings under both non-stress and salt-stress conditions. Wheat seedlings with TL-6 treatments under different levels of NaCl stress increased proline content by an average of 11%, ascorbate 15%, and glutathione 28%; and decreased the contents of malondialdehyde (MDA) by an average of 19% and hydrogen peroxide (H2O2) 13%. The TL-6 treatments induced the transcriptional level of reactive oxygen species (ROS) scavenging enzymes, leading to the increases of glutathione s-transferase (GST) by an average of 17%, glutathione peroxidase (GPX) 16%, ascorbate peroxidase (APX) 17%, glutathione reductase (GR) 18%, dehydroascorbate reductase (DHAR) 5%. Our results indicate that the beneficial strain of TL-6 effectively scavenged ROS under NaCl stress through modulating the activity of ROS scavenging enzymes, regulating the transcriptional levels of ROS scavenging enzyme gene expression, and enhancing the nonenzymatic antioxidants in wheat seedling in response to salt stress. Our present study provides a new insight into the mechanisms of TL-6 can activate the enzymatic and nonenzymatic antioxidant defense systems and enhance wheat seedling tolerance to different levels of salt stress at physiological, biochemical and molecular levels.

scholarly journals Ascorbate-Mediated Modulation of Cadmium Stress Responses: Reactive Oxygen Species and Redox Status in Brassica napus

2020 ◽  
Vol 11 ◽  
Author(s):  
Ha-il Jung ◽  
Bok-Rye Lee ◽  
Mi-Jin Chae ◽  
Eun-Jin Lee ◽  
Tae-Gu Lee ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Brassica Napus ◽  
Oilseed Rape ◽  
Antioxidant Defense ◽  
Redox Status ◽  
Oxygen Species ◽  
Cd Uptake ◽  
Defense Systems ◽  
Cd Uptake And Accumulation

The role of ascorbate (AsA) in antioxidant defense system-associated resistance to cadmium (Cd) in oilseed rape plants has not yet been clearly demonstrated. The present study investigated the critical role of exogenous AsA on the physiological and biochemical responses of reactive oxygen species (ROS) and antioxidant scavenging defense systems in oilseed rape (Brassica napus L. cv. Tammi) seedlings exposed to Cd. Cd (10 μM) treatment led to significant reductions in plant growth; increases in the levels of superoxide anion radical, hydrogen peroxide, and malondialdehyde; and increases in Cd uptake and accumulation by the roots and shoots in hydroponically grown 10-day-old seedlings. Moreover, it reduced AsA content and AsA redox ratios, which have been correlated with reductions in glutathione (GSH) and/or nicotinamide adenine dinucleotide phosphate (NADPH) redox status. However, exogenously applying AsA to Cd-exposed seedlings decreased Cd-induced ROS, improved antioxidant defense systems by increasing AsA, GSH, and NADPH contents, and increased Cd uptake and accumulation in both roots and shoots of the plants. These results provided evidence that the enhancement in AsA redox status can be linked to an increase in the GSH and/or NADPH redox ratios through the induction of the AsA–GSH–NADPH cycle. Thus, these results suggest that exogenous AsA application to oilseed rape seedlings under Cd stress might alleviate the overall Cd toxicity by regulating the homeostasis of the AsA–GSH–NADPH cycle, which reestablishes the steady-state cellular redox status.

Protective role of carbon dioxide (CO2) in generation of reactive oxygen species

2015 ◽  
Vol 411 (1-2) ◽  
pp. 317-330 ◽  
Author(s):  
Sergey Bolevich ◽  
Alekandr Haritonovic Kogan ◽  
Vladimir Zivkovic ◽  
Dusan Djuric ◽  
Aleksey Aleksejevic Novikov ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Reactive Oxygen Species ◽  
Reactive Oxygen ◽  
Protective Role ◽  
Oxygen Species ◽  
Carbon Dioxide Co2

scholarly journals Mechanical Wounding Induces Catalase Gene (VsCat) in Leaves of Common Vetch

2021 ◽  
Author(s):  
Saeid Abu-Romman ◽  
Tarek G. Ammari
Keyword(s):  
Time Course ◽  
Oxygen Species ◽  
Biotic Factors ◽  
Quantitative Real Time Pcr ◽  
Mechanical Wounding ◽  
Common Vetch ◽  
Catalase Gene ◽  
Defense Systems ◽  
Time Course Study ◽  
Scavenging Enzymes

Background: In plants, wounding can result from mechanical injuries or from biotic factors induced by herbivores infestation and pathogen infection. Wounding enhances the production of reactive oxygen species (ROS). Enzymatic and nonenzymatic defense systems have been reported in plants to immediately combat increased levels of ROS. Plant catalases are encoded by a multigene family and are the major scavenging enzymes catalyzing the dismutation of toxic hydrogen peroxide to water and dioxygen. Methods: In the preasent work, a quantitative real-time PCR was used to quantify the expression level of a catalase gene from common vetch (Vicia sativa; VsCat) in response to mechanical wounding. Result: The results of the time course study showed that the transcript levels of VsCat were significantly increased in wounded leaves at all-time points examined with a peak expression of 7.6 folds at 2 h post wounding. The increased expression of VsCat might represent a direct defense against elevated H2O2 generated during wounding.

scholarly journals The Protective Role of 1,8-Dihydroxynaphthalene–Melanin on Conidia of the Opportunistic Human Pathogen Aspergillus fumigatus Revisited: No Role in Protection against Hydrogen Peroxide and Superoxides

mSphere ◽  
2022 ◽  
Author(s):  
E. M. Keizer ◽  
I. D. Valdes ◽  
B. L. McCann ◽  
E. M. Bignell ◽  
H. A. B. Wösten ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Aspergillus Fumigatus ◽  
Protective Role ◽  
Oxygen Species ◽  
Human Pathogen ◽  
Opportunistic Pathogens ◽  
Green Pigment ◽  
Content Type ◽  
Opportunistic Human Pathogen

Opportunistic pathogens like Aspergillus fumigatus have strategies to protect themselves against reactive oxygen species like hydrogen peroxides and superoxides that are produced by immune cells. DHN-melanin is the green pigment on conidia of Aspergillus fumigatus and more than 2 decades ago was reported to protect conidia against hydrogen peroxide.

scholarly journals The Protective Role of Bacillus Anthracis Exosporium in Macrophage-Mediated Killing by Nitric Oxide

2007 ◽  
Author(s):  
John Weaver ◽  
Tae Jin Kang ◽  
Kimberly Raines ◽  
Guan-Liang Cao ◽  
Stephen Hibbs ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Bacillus Anthracis ◽  
Protective Role ◽  
Oxygen Species ◽  
Activated Macrophages ◽  
Positive Bacterium ◽  
Bacterium Bacillus ◽  
Oxide Synthase ◽  
Inducible Nitric Oxide

The ability of the endospore-forming, gram-positive bacterium Bacillus anthracis to survive exposure to antibacterial killing mechanisms by activated macrophages is key to its germination and survival. These antibacterial killing mechanisms include, but are not limited to the generation of free radicals such as nitric oxide (•NO) and superoxide (O2•−) from the upregulation of inducible nitric oxide synthase (NOS 2) along with products derived from them, e.g., peroxynitrite (ONOO−), as part of microbicidal activity. However questions still remain as to how these species are involved in microbial killing, specifically with respect to B. anthracis. In a previous study, we demonstrated that exposure of primary murine macrophages to sonicated B. anthracis endospores up-regulated NOS 2 and demonstrated a •NO-dependent bactericidal response, but unanswered in that study was which of the NOS 2-derived reactive oxygen species was responsible for the observed bactericidal response. Since NOS 2 also generates O2•−, experiments were designed to determine whether NOS 2 formed ONOO− from the reaction of •NO with O2•− and if so, was ONOO− microbicidal toward B. anthracis.

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