Superoxide dismutase and catalase in Frankia

1986 ◽  
Vol 32 (5) ◽  
pp. 409-413 ◽  
Author(s):  
D. Bernie Steele ◽  
Mark D. Stowers
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Nitrogen Fixation ◽  
Methyl Viologen ◽  
Nitrogenase Activity ◽  
Nitrogen Fixing ◽  
Additional Mechanism ◽  
Sod Activity ◽  
Cell Extracts ◽  
Cell Components

Superoxide dismutase (SOD) and catalase (CAT) are important enzymes in the protection of cell components from oxidation via superoxide free radicals [Formula: see text] and hydrogen peroxide (H2O2). SOD and CAT activities in Frankia, under non-nitrogen fixing conditions, are among the highest reported in prokaryotes. A sixfold increase in SOD activity (2150 units/mg of protein) and a twofold increase in CAT activity (413 units/mg of protein) was seen in cultures derepressed for nitrogen fixation compared with ammonium-grown cultures. Frankia possesses a manganese-containing SOD (MnSOD) when grown with ammonium as the nitrogen source. An additional SOD isozyme containing iron (FeSOD) was detected in cell extracts when grown with dinitrogen. Methyl viologen induced higher activity of the MnSOD in ammonium-grown cultures but failed to induce the FeSOD. During derepression of nitrogenase activity, the simultaneous induction of SOD and CAT was detected. The presence of a new iron-containing SOD under nitrogen-fixing conditions could provide an additional mechanism for protection from O2 toxicity.

Molybdenum enhancement of nitrogen fixation in a Mo-starved Azotobacter vinelandii Nif− mutant

1982 ◽  
Vol 28 (10) ◽  
pp. 1173-1180 ◽  
Author(s):  
William J. Page ◽  
S. Karen Collinson
Keyword(s):  
Molecular Weight ◽  
Nitrogen Fixation ◽  
Azotobacter Vinelandii ◽  
Nitrogenase Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Nitrogen Fixing ◽  
Wild Type ◽  
Cell Extracts ◽  
In The Wild ◽  
Dinitrogenase Reductase

Molybdenum (Mo)-starved wild-type and Nif− strains of Azotobacter vinelandii reduced acetylene (fixed nitrogen) in Mo-limited nitrogen-free medium. Vanadate enhanced this activity in all of the strains. Molybdate caused repression of nitrogenase activity in the Nif− mutants and enhanced the nitrogenase activity in the wild type. The nitrogenase activity in the Nif− mutant UW3, however, was enhanced by Mo, became maximal after 3 h, and then declined to zero after 10 h of incubation. The activation of nitrogenase by Mo followed a 5- to 10-min lag and was inhibited when streptomycin or rifampin was added with Mo. Examination of Mo-starved nitrogen-fixing UW3 cell extracts by two-dimensional polyacrylamide gel electrophoresis revealed molecular weight 57 000, 50 000, and 30 000 proteins that were Mo and NH4+ repressive. The molecular weight 30 000 protein appeared in the same position on the gel as the wild-type dinitrogenase reductase, although UW3 did not produce this protein under Mo-sufficient nitrogen-fixing conditions. Cell extracts prepared 3 h after Mo addition lacked the molecular weight 57 000 and 50 000 proteins but contained a new protein corresponding to the β subunit of dinitrogenase. When UW3 nitrogenase activity was lost, the dinitrogenase reductase-like protein also was absent. The results suggest that a complex active in nitrogen fixation may form between components of the traditional Mo-sufficient and alternative Mo-starved cell nitrogen fixation systems.

Nitrogen fixation

1976 ◽  
Vol 274 (934) ◽  
pp. 341-358 ◽  
Keyword(s):  
Nitrogen Fixation ◽  
Metabolic Regulation ◽  
Higher Plants ◽  
Focal Point ◽  
Nitrogenase Activity ◽  
Nitrogen Fixing ◽  
Blue Green Algae ◽  
International Biological Programme ◽  
The 1960S ◽  
Biological Programme

The International Biological Programme served as a focal point for studies on biological nitrogen fixation during the 1960s. The introduction of the acetylene reduction technique for measuring nitrogenase activity in the field led to estimates becoming available of the contribution of lichens, blue-green algae, nodulated non-legumes and bacterial-grass associations, as well as of legumes. Other studies carried out on the physiology and biochemistry of the process led to the eventual purification and characterization of the nitrogenase enzyme. These studies, collectively, provided the springboard for current work, so essential in view of the present energy crisis, on how to increase the use and efficiency of nitrogen-fixing plants, on the metabolic regulation of the nitrogenase enzyme and on the genetics of the nitrogen-fixing process, both in higher plants and in free-living micro-organisms.

para-Hydroxybenzoate supported nitrogen fixation in Azotobacter vinelandii strain OP (13705)

1988 ◽  
Vol 34 (11) ◽  
pp. 1271-1275 ◽  
Author(s):  
Jay B. Peterson ◽  
Lynn S. Peterson
Keyword(s):  
Nitrogen Fixation ◽  
Cytoplasmic Membrane ◽  
Azotobacter Vinelandii ◽  
Nitrogenase Activity ◽  
Molecular Nitrogen ◽  
Carbon Sources ◽  
Gel Filtration ◽  
Cell Extracts ◽  
Reduction Assay ◽  
Membrane Bound

Azotobacter vinelandii cells grew with molecular nitrogen and p-hydroxybenzoate as the sole added nitrogen and carbon sources. Nitrogenase activity in p-hydroxybenzoate grown cells was demonstrated with the acetylene reduction assay. Cell extracts contained the enzymes p-hydroxybenzoate hydroxylase (EC 1.14.13.2) and protocatechuate 3,4-dioxygenase (EC 1.13.1.3); oxygenases associated with p-hydroxybenzoate metabolism. These enzymes separated from respiration particles with gel filtration chromatography, indicating that they are soluble and not membrane bound. This evidence indicates that oxygen enters to the inner face of the cytoplasmic membrane during nitrogen fixation.

scholarly journals Contribution of Mn-Cofactored Superoxide Dismutase (SodA) to the Virulence of Streptococcus agalactiae

2001 ◽  
Vol 69 (8) ◽  
pp. 5098-5106 ◽  
Author(s):  
Claire Poyart ◽  
Elisabeth Pellegrini ◽  
Olivier Gaillot ◽  
Claire Boumaila ◽  
Marina Baptista ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Streptococcus Agalactiae ◽  
Specific Activity ◽  
Infection Model ◽  
Mouse Bone Marrow ◽  
Group B Streptococci ◽  
Bacterial Killing ◽  
Cell Extracts

ABSTRACT Superoxide dismutases convert superoxide anions to molecular oxygen and hydrogen peroxide, which, in turn, is metabolized by catalases and/or peroxidases. These enzymes constitute one of the major defense mechanisms of cells against oxidative stress and hence play a role in the pathogenesis of certain bacteria. We previously demonstrated that group B streptococci (GBS) possess a single Mn-cofactored superoxide dismutase (SodA). To analyze the role of this enzyme in the pathogenicity of GBS, we constructed a sodA-disrupted mutant of Streptococcus agalactiae NEM316 by allelic exchange. This mutant was subsequently cis complemented by integration into the chromosome of pAT113/Sp harboring the wild-typesodA gene. The SOD specific activity detected by gel analysis in cell extracts confirmed that active SODs were present in the parental and complemented strains but absent in thesodA mutant. The growth rates of these strains in standing cultures were comparable, but the sodA mutant was extremely susceptible to the oxidative stress generated by addition of paraquat or hydrogen peroxide to the culture medium and exhibited a higher mutation frequency in the presence of rifampin. In mouse bone marrow-derived macrophages, the sodA mutant showed an increased susceptibility to bacterial killing by macrophages. In a mouse infection model, after intravenous injection the survival of thesodA mutant in the blood and the brain was markedly reduced in comparison to that of the parental and complemented strains whereas only minor effects on survival in the liver and the spleen were observed. These results suggest that SodA plays a role in GBS pathogenesis.

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.

scholarly journals Inhibition of Aflatoxin Production by Paraquat and External Superoxide Dismutase in Aspergillus flavus

Toxins ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 107 ◽  
Author(s):  
Tomohiro Furukawa ◽  
Shohei Sakuda
Keyword(s):  
Superoxide Dismutase ◽  
Aspergillus Flavus ◽  
Regulatory Protein ◽  
Fungal Growth ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Sod Activity ◽  
Fungal Cell ◽  
Cell Extracts ◽  
Ic50 Value

Aflatoxin contamination of crops is a worldwide problem, and elucidation of the regulatory mechanism of aflatoxin production, for example relative to the oxidative–antioxidative system, is needed. Studies have shown that oxidative stress induced by reactive oxygen species promotes aflatoxin production. However, superoxide has been suggested to have the opposite effect. Here, we investigated the effects of the superoxide generator, paraquat, and externally added superoxide dismutase (SOD) on aflatoxin production in Aspergillus flavus. Paraquat with an IC50 value of 54.9 µM inhibited aflatoxin production without affecting fungal growth. It increased cytosolic and mitochondrial superoxide levels and downregulated the transcription of aflatoxin biosynthetic cluster genes, including aflR, a key regulatory protein. The addition of bovine Cu/ZnSOD to the culture medium suppressed the paraquat-induced increase in superoxide levels, but it did not fully restore paraquat-inhibited aflatoxin production because bovine Cu/ZnSOD with an IC50 value of 17.9 µg/mL itself inhibited aflatoxin production. Externally added bovine Cu/ZnSOD increased the SOD activity in fungal cell extracts and upregulated the transcription of genes encoding Cu/ZnSOD and alcohol dehydrogenase. These results suggest that intracellular accumulation of superoxide impairs aflatoxin production by downregulating aflR expression, and that externally added Cu/ZnSOD also suppresses aflatoxin production by a mechanism other than canonical superoxide elimination activity.

scholarly journals Rhizobium etli Genetically Engineered for the Heterologous Expression of Vitreoscilla sp. Hemoglobin: Effects on Free-Living and Symbiosis

1999 ◽  
Vol 12 (11) ◽  
pp. 1008-1015 ◽  
Author(s):  
Mario Ramírez ◽  
Brenda Valderrama ◽  
Raúl Arredondo-Peter ◽  
Mario Soberón ◽  
Jaime Mora ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Heterologous Expression ◽  
Energy Content ◽  
Nitrogenase Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Rhizobium Etli ◽  
Free Living ◽  
Cell Extracts ◽  
Bean Plants

Oxygen concentration is an environmental signal that regulates nitrogen fixation in the Rhizobium-legume symbiosis. We investigated the effect of the heterologous expression of Vitreoscilla sp. hemoglobin (VHb), which is an oxygen-binding protein, in Rhizobium etli. The vhb gene and its native promoter were subcloned in the plasmid pMR4 and transformed into the R. etli strain CE3. Free-living cultures of engineered R. etli CE3 expressed the vhb gene, as shown by the CO-difference spectral and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analyses of cell extracts. The expression of vhb in free-living R. etli grown under most limiting oxygen concentrations resulted in an increase in respiratory activity, chemical energy content, and expression of the nitrogen-fixation gene nifHc. Bacteroids isolated from nodules of bean plants inoculated with the engineered R. etli CE3 expressed the vhb gene, as shown by RNA slot-blot analysis. Bean plants inoculated with the engineered strain exhibited higher nitrogenase activity and total nitrogen content (68% and 14 to 53%, respectively) than bean plants inoculated with the R. etli wild type. These results suggest that the synthesis of VHb in engineered R. etli stimulated the respiratory efficiency of free-living rhizobia, and also probably of symbiotic bacteroids, thus leading to higher levels of symbiotic nitrogen fixation.

scholarly journals nifH Sequences and Nitrogen Fixation in Type I and Type II Methanotrophs

2001 ◽  
Vol 67 (9) ◽  
pp. 4009-4016 ◽  
Author(s):  
Ann J. Auman ◽  
Catherine C. Speake ◽  
Mary E. Lidstrom
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
Freshwater Lake ◽  
Type I ◽  
Type Ii ◽  
Nitrogen Fixing ◽  
Protein Sequence Analysis ◽  
High Identity ◽  
Rice Roots ◽  
Methane Oxidizing Bacteria

ABSTRACT Some methane-oxidizing bacteria (methanotrophs) are known to be capable of expressing nitrogenase and utilizing N2 as a nitrogen source. However, no sequences are available fornif genes in these strains, and the known nitrogen-fixing methanotrophs are confined mainly to a few genera. The purpose of this work was to assess the nitrogen-fixing capabilities of a variety of methanotroph strains. nifH gene fragments from four type I methanotrophs and seven type II methanotrophs were PCR amplified and sequenced. Nitrogenase activity was confirmed in selected type I and type II strains by acetylene reduction. Activities ranged from 0.4 to 3.3 nmol/min/mg of protein. Sequence analysis shows that thenifH sequences from the type I and type II strains cluster with nifH sequences from other gamma proteobacteria and alpha proteobacteria, respectively. The translatednifH sequences from three Methylomonas strains show high identity (95 to 99%) to several published translated environmental nifH sequences PCR amplified from rice roots and a freshwater lake. The translated nifHsequences from the type II strains show high identity (94 to 99%) to published translated nifH sequences from a variety of environments, including rice roots, a freshwater lake, an oligotrophic ocean, and forest soil. These results provide evidence for nitrogen fixation in a broad range of methanotrophs and suggest that nitrogen-fixing methanotrophs may be widespread and important in the nitrogen cycling of many environments.

Superoxide dismutase mimetic drug tempol aggravates anti-GBM antibody-induced glomerulonephritis in mice

2010 ◽  
Vol 299 (2) ◽  
pp. F445-F452 ◽  
Author(s):  
Hua Lu ◽  
Junhui Zhen ◽  
Tianfu Wu ◽  
Ai Peng ◽  
Ting Ye ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Basement Membrane ◽  
Glomerular Basement Membrane ◽  
Immunohistochemical Staining ◽  
Treated Group ◽  
First Line ◽  
Sod Activity ◽  
Leukocyte Influx

Oxidative stress plays an important role in the pathogenesis of anti-glomerular basement membrane antibody-induced glomerulonephritis (anti-GBM-GN). Superoxide dismutase (SOD) is the first line of defense against oxidative stress by converting superoxide to hydrogen peroxide (H2O2). We investigated the effect of the SOD mimetic drug tempol on anti-GBM-GN in mice. 129/svJ mice were challenged with rabbit anti-mouse-GBM sera to induce GN and subsequently divided into tempol (200 mg·kg−1·day−1, orally) and vehicle-treated groups. Routine histology, SOD and catalase activities, malondialdehyde (MDA), H2O2, and immunohistochemical staining for neutrophils, lymphocytes, macrophages, p65-NF-κB, and osteopontin were performed. Mice with anti-GBM-GN had significantly reduced renal SOD and catalase activities and increased H2O2 and MDA levels. Unexpectedly, tempol administration exacerbated anti-GBM-GN as evidenced by intensification of proteinuria, the presence of severe crescentic GN with leukocyte influx, and accelerated mortality in the treated group. Tempol treatment raised SOD activity and H2O2 level in urine, upregulated p65-NF-κB and osteopontin in the kidney, but had no effect on renal catalase activity. Thus tempol aggravates anti-GBM-GN by increasing production of H2O2 which is a potent NF-κB activator and as such can intensify inflammation and renal injury. This supposition is supported by increases seen in p65-NF-κB, osteopontin, and leukocyte influx in the kidneys of the tempol-treated group.

scholarly journals Superoxide Dismutase-Deficient Mutants ofHelicobacter pylori Are Hypersensitive to Oxidative Stress and Defective in Host Colonization

2001 ◽  
Vol 69 (6) ◽  
pp. 4034-4040 ◽  
Author(s):  
Richard W. Seyler ◽  
Jonathan W. Olson ◽  
Robert J. Maier
Keyword(s):  
Oxidative Stress ◽  
Superoxide Dismutase ◽  
Virulence Factor ◽  
Type Strain ◽  
Wild Type Strain ◽  
Spontaneous Mutation ◽  
Wild Type ◽  
Sod Activity ◽  
Cell Extracts ◽  
H Pylori

ABSTRACT Superoxide dismutase (SOD) is a nearly ubiquitous enzyme among organisms that are exposed to oxic environments. The single SOD ofHelicobacter pylori, encoded by the sodB gene, has been suspected to be a virulence factor for this pathogenic microaerophile, but mutations in this gene have not been reported previously. We have isolated mutants with interruptions in thesodB gene and have characterized them with respect to their response to oxidative stress and ability to colonize the mouse stomach. The sodB mutants are devoid of SOD activity, based on activity staining in nondenaturing gels and quantitative assays of cell extracts. Though wild-type H. pylori is microaerophilic, the mutants are even more sensitive to O2 for both growth and viability. While the wild-type strain is routinely grown at 12% O2, growth of the mutant strains is severely inhibited at above 5 to 6% O2. The effect of O2 on viability was determined by subjecting nongrowing cells to atmospheric levels of O2 and plating for survivors at 2-h time intervals. Wild-type cell viability dropped by about 1 order of magnitude after 6 h, while viability of the sodBmutant decreased by more than 6 orders of magnitude at the same time point. The mutants are also more sensitive to H2O2, and this sensitivity is exacerbated by increased O2 concentrations. Since oxidative stress has been correlated with DNA damage, the frequency of spontaneous mutation to rifampin resistance was studied. The frequency of mutagenesis of ansodB mutant strain is about 15-fold greater than that of the wild-type strain. In the mouse colonization model, only 1 out of 23 mice inoculated with an SOD-deficient mutant of a mouse-adapted strain became H. pylori positive, while 15 out of 17 mice inoculated with the wild-type strain were shown to harbor the organism. Therefore, SOD is a virulence factor which affects the ability of this organism to colonize the mouse stomach and is important for the growth and survival of H. pylori under conditions of oxidative stress.

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