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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 58 (1989), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The synthesis of Mn- and FeSODs in response to temperature changes was examined in strains of Escherichia coli with different mutations in sod and htpR genes. Growth at or shift to elevated temperatures induced FeSOD but not MnSOD. The induction of FeSOD by heat was inhibited by chloramphenicol and was independent of the heat shock (htpR-controlled) regulon. FeSOD was more stable at 42°C than was MnSOD.
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 28 (1985), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Paraquat-resistant Escherichia coli mutants were isolated. The mutants were 10- to 50-fold more resistant to paraquat than the wild type. The wild type was more responsive to the presence of paraquat by inducing higher levels of the manganese-containing superoxide dismutase (MnSOD). Thus, in minimal medium, 0.1 mM paraquat caused a 5-fold increase in MnSOD in the wild type while it had no effect on the level of MnSOD in the mutants. Yet, 50 mM paraquat exerted a dramatic induction of SOD in the mutant strains when grown in trypticase soy yeast extract (TSY) medium. In TSY medium, catalase was not significantly affected by paraquat in all the strains tested. Resistance to paraquat in these mutant strains is, therefore, unrelated to their capacity to detoxify superoxide or hydrogen peroxide.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 25 (1984), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Nalidixic acid caused a significant increase in the Mn-containing superoxide dismutase (MnSOD) of Escherichia coli. The maximum stimulatory effect of nalidixic acid on MnSOD biosynthesis was observed at 0.1 mM. The stimulatory effect of nalidixic acid was not due to increases in the intracellular flux of O−2, but rather to its ability to chelate Fe2+. Furthermore, 2,2′-dipyridyl and 1,10-phenanthroline were shown to cause a 7- to 20-fold increase in the MnSOD of E. coli. It is proposed that the repressor for MnSOD is an iron-containing protein.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 42 (1987), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effect of oxygen, paraquat (PQ2+; 1,1′-dimethyl-4,4′-bipyridinium dichloride) and 2,2′-dipyridyl (2,2′-DP) on the synthesis of superoxide dismutase (SOD) in various microorganisms was examined to determine whether the control of SOD biosynthesis in other prokaryotes is similar to that in Escherichia coli. All of the strains tested, with the exception of Alcaligenes faecalis, exhibited SOD levels proportional to the concentration of oxygen in the growth media. Paraquat induced SOD in all of the strains surveyed except Staphylococcus epidermidis, Streptococcus faecalis, and Listeria monocytogenes. The iron chelator, 2,2′-DP, induced SOD in Proteus vulgaris, Enterobacter cloacae and Staphylococcus aureus, but decreased the activity of SOD in A. faecalis and Pseudomonas aeruginosa and had no effect in S. epidermidis, S. faecalis or L. monocytogenes. The data indicate that the induction of SOD in P. vulgaris, E. cloacae, and Salmonella typhimurium is similar to that found in E. coli and suggest that the mechanism of SOD regulation in E. coli may be representative of the Enterobacteriaceae family as a whole.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 50 (2004), S. 0 
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Vibrio vulnificus has proven difficult to culture from water or shellfish during winter months, which is attributed to the viable but nonculturable (VBNC) state. Because reactive oxygen species were found to be involved in the low temperature-induced entrance of V. vulnificus into this state, we generated an oxyR mutant which lacks catalase activity. This strain is nonculturable on solid media even at ambient temperature, due to the presence of H2O2 in such media. Low temperature incubation of the parent resulted in loss of catalase activity, making the cells H2O2 sensitive, and paralleling the loss of culturability (entry into the VBNC state). Thus, cells of V. vulnificus in the VBNC state are likely exhibiting this response to low in situ temperature and only when the artificial condition of laboratory culture is attempted are the cells nonculturable due to cold-induced loss of catalase activity. To our knowledge, this is the first study providing direct evidence for the metabolic basis of nonculturability and the viable but nonculturable state.
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  • 6
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A strategy for functional gene replacement in the chromosome of Lactobacillus gasseri is described. The phospho-β-galactosidase II gene (lacII) was functionally replaced by the manganese superoxide dismutase (MnSOD) gene (sodA) from Streptococcus thermophilus, by adapting the insertional inactivation method described for lactobacilli [Russell, W.M. and Klaenhammer, T.R. 2001 Efficient system for directed integration into the Lactobacillus acidophilus and Lactobacillus gasseri chromosomes via homologous recombination. Appl. Environ. Microbiol. 67, 4361–4364]. L. gasseri carrying the heterologous sodA gene grew on lactose as efficiently as the wild-type parent. An active MnSOD was expressed in the transgenic strain, and the enzyme migrated on PAGE-SOD activity gels to the same position as that of MnSOD from S. thermophilus. The expression of MnSOD from a single copy of sodA integrated in the chromosome of L. gasseri provided enhanced tolerance to hydrogen peroxide, and extended the viability of carbon/energy starved cultures stored at 25 °C. This is the first report showing the successful utilization of the pORI plasmids system to generate marker-free gene integration in L. gasseri strains.
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 14 (1994), S. 0 
    ISSN: 1574-6976
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract: Aerobic life-style offers both benefits and risks to living cells. The major risk comes from the formation of reactive oxygen intermediates (i.e. superoxide radical, O−2; hydrogen peroxide, H2O2; and hydroxyl radical, OH) during normal oxygen metabolism. However, living cells are able to cope with oxygen toxicity by virtue of a unique set of antioxidant enzymes that scavenge O−2 and H2O2, and prevent the formation OH. Superoxide dismutases (SODs; EC 1.15.1.1) are metalloenzymes essential for aerobic survival. Escherichia coli contains two forms of this enzyme: an iron-containing enzyme (FeSOD) and a manganese-containing enzyme (MnSOD). In E. Coli, MnSOD biosynthesis is under rigorous control. The enzyme is induced in response to a variety of environmental stress conditions including exposure to oxygen, redox cycling compounds such as paraquat which exacerbate the level of intracellular superoxide radicals, iron chelation (i.e. iron deprivation), and oxidants. A model for the regulation of the MnSOD has been proposed in which the MnSOD gene (sodA) is negatively regulated at the level of transcription by an iron-containing redox-sensitive repressor protein. The effect of ironchelation most probably results in removal of the iron necessary for repressor activity. Recent studies have shown that sodA expression is regulated by three iron-dependent regulatory proteins, Fur (ferric uptake regulation), Fnr (fumarate nitrate regulation) and SoxR (superoxide regulon), and by the ArcA/ArcB (aerobic respiratkm control) system. The potential Fur-, Fnr- and AreA-binding sites in the sodA promoter region have bcen identified by using different cis-acting regulatory mutations that caused anaerobic derepression of the gene. An updated model is presented to accommodate these findings and explain the biological significance of regulation by multi-regulatory elements in response to multi-environmental effectors.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 26 (1987), S. 531-536 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The effects of oxygen (100%), paraquat (0.5 mM), and copper (0.1 mM) on the growth and the biosynthesis of the antioxidant enzymes, superoxide dismutase (SOD) and catalase, were studied in Saccharomyces cerevisiae grown in glucose-limited chemostat cultures. The effect of dilution rates (D, h−1) on cell mass, glucose consumption, ethanol production, oxygen uptake, and specific activities of SOD and catalase were also investigated at each steady state. SOD was optimally produced at D-values between 0.22 and 0.26 h−1 in the presence of oxygen or paraquat, and at D-values greater than 0.17 h−1 when copper was used. On the other hand, catalase activity decreased with increasing D-values. However, the presence of copper or 100% oxygen repressed catalase activity at low D-values (D〈0.1 h−1), and decreased the rate of oxygen uptake at all D-values tested. The presence of paraquat affected the rate of oxygen uptake only at high D-values (D〉0.22 h−1). We also studied the effect of oxygen concentration on the biosynthesis of SOD and catalase at D=0.1 h−1. The data clearly show that synthesis of SOD and catalase, though correlated with changes in oxygen tension, are independent of one another.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 1 (1986), S. 187-193 
    ISSN: 1476-5535
    Keywords: Saccharomyces cerevisiae ; Cytochromec ; Superoxide dismutase ; Catalase ; Oxyradicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Two strains ofSaccharomyces cerevisiae were used to study the synthesis of superoxide dismutase. One strain (cytochromec-deficient) contained 5–10% of the normal amounts of total cytochromec, while the other strain was a wild type. The cytochromec-deficient mutant had lower specific growth rate, growth yield, and oxygen uptake than the wild type. The superoxide dismutase and catalase activities, in both strains, were significantly lower under anaerobic than under aerobic conditions. Furthermore, under aerobic conditions the mutant contained higher levels of superoxide dismutase than the wild type which may be attributed to the higher intracellular flux of superoxide radicals caused by the cytochromec deficiency. The mutant also showed a lower level of catalase which was due to glucose repression.
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  • 10
    ISSN: 1617-4623
    Keywords: Escherichia coli ; Superoxide dismutase (SOD) ; Integration host factor (IHF) ; Mobility-shift
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We used the clectrophoretic mobility-shift assay to reveal specific DNA-protein interactions between DNA fragments containing the sodA promoter and proteins present in Escherichia coli cell-free extracts. We have shown specific binding of several E. coli proteins to sodA promoter sequences and identified one of these proteins as the integration host factor (IHF). Mobility-shift experiments with cell-free extracts prepared from himA (IHF-negative) mutant strains lacked a specific DNA-protein band relative to shifts made with wild-type extracts. Several potential IHF-binding sites were identified in the sodA promoter region. Purified IHF was found to bind specifically to DNA fragments containing the sodA promoter. Further evidence presented suggests that IHF binds to multiple sites in the sodA promoter. We have also investigated the transcriptional regulation of sodA by monitoring the expression of a sodA-lacZ fusion gene in an IHF-negative E. coli strain under different growth conditions. Under aerobic conditions, a deletion in himA (IHF subunit α) resulted in a 60% increase in sodA expression, while having no effect on induction by paraquat. The same deletion in himA did not cause derepression of sodA-lacZ during anaerobic growth, but resulted in an increased response (about twofold) to the presence of 2,2′-dipyridyl compared to the isogenic wild-type strain.
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