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  • 1
    Electronic Resource
    Electronic Resource
    Roles of manganese and iron in the regulation of the biosynthesis of manganese-superoxide dismutase in Escherichia coli (1994)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 14 (1994), S. 0 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6976.1994.tb00105.x
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  • 2
    Electronic Resource
    Electronic Resource
    Marker-free chromosomal integration of the manganese superoxide dismutase gene (sodA) from Streptococcus thermophilus into Lactobacillus gasseri (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 246 (2005), S. 0 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/j.femsle.2005.03.044
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of temperature and htpR on the biosynthesis of superoxide dismutase in Escherichia coli (1989)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 58 (1989), S. 0 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1989.tb03033.x
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  • 4
    Electronic Resource
    Electronic Resource
    Induction of the manganese-containing superoxide dismutase in Escherichia coli by nalidixic acid and by iron chelators (1984)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 25 (1984), S. 0 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1984.tb01463.x
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  • 5
    Electronic Resource
    Electronic Resource
    Isolation of paraquat-resistant mutants of Escherichia coli: lack of correlation between resistance and the activity of superoxide dismutase (1985)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 28 (1985), S. 0 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1985.tb00771.x
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  • 6
    Electronic Resource
    Electronic Resource
    Biosynthesis of superoxide dismutase in eight prokaryotes: Effects of oxygen, paraquat and an iron chelator (1987)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 42 (1987), S. 0 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1987.tb02295.x
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  • 7
    Electronic Resource
    Electronic Resource
    Biosynthesis of superoxide dismutase and catalase in chemostat culture of Saccharomyces cerevisiae (1987)
    Springer
    Applied microbiology and biotechnology 26 (1987), S. 531-536 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00253027
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  • 8
    Electronic Resource
    Electronic Resource
    Thermal boundary condition effects on heat transfer in turbulent rough-wall boundary layers (1992)
    Springer
    Heat and mass transfer 27 (1992), S. 131-140 
    Details
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung In dieser Arbeit werden Messungen und Berechnungen gezeigt, die den Einfluß der thermischen Randbedingungen auf die Wärmeübertragung in turbulenten Grenzschichten an rauhen Wänden untersuchen. Es werden Messungen der Stanton Zahl für turbulente Luftströmung über rauhe Platten an zwei separaten Oberflächen unter einer Reihe von thermischen Randbedingungen dargestellt. Die betrachteten Fälle sind konstante Wandtemperatur, konstanter Wärmestrom durch die Wand, abgestufte Wandtemperatur und stückweise konstante Wandtemperatur. Diese Messungen, sowie Daten anderer Untersuchungen, werden mit Berechnungen durch Finite-Differenzen Lösungen des Diskrete-Elemente-Rauhheits-Modells und Superpositionslösungen verglichen. Berechnungen und Messungen liegen in guter bis ausgezeichneter Übereinstimmung.
    Notes: Abstract Measurements and predictions are presented which investigate the effects of thermal boundary condition on heat transfer in the turbulent rough-wall boundary layer. Stanton number measurements are reported for the turbulent flow of air over rough plates with a variety of thermal boundary conditions on two separate rough surfaces. The cases considered are constant wall temperature, constant wall heat flux, step wall temperature, and piecewise linear wall temperature distributions. These measurements and data from other sources are compared with predictions using finite difference solutions of the discrete element roughness model and with superposition solutions. The predictions and the measurements are in good to excellent agreement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01599926
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  • 9
    Electronic Resource
    Electronic Resource
    Binding of integration host factor (IHF) to the Escherichia coli sodA gene and its role in the regulation of a sodA-lacZ fusion gene (1995)
    Springer
    Molecular genetics and genomics 246 (1995), S. 228-235 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00294686
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  • 10
    Electronic Resource
    Electronic Resource
    Cloning and expression of the manganese superoxide dismutase gene of Escherichia coli in Lactococcus lactis and Lactobacillus gasseri (1993)
    Springer
    Molecular genetics and genomics 239 (1993), S. 33-40 
    Details
    ISSN: 1617-4623
    Keywords: Escherichia coli ; Superoxide dismutase ; Fusion protein ; Lactococcus ; Lactobacillus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Escherichia coli sodA gene encoding the antioxidant enzyme Mn-containing superoxide dismutase (MnSOD), was cloned in the expression vector pMG36e. This vector has a multiple cloning site down-stream of a promoter and Shine-Dalgarno sequences derived from Lactococcus. The protein-coding region of sodA from E. coli was amplified by the polymerase chain reaction, using a thermocycler and Taq DNA polymerase before cloning into pMG36e. When introduced into E. coli, the recombinant plasmid expressed the predicted fusion protein, both in the presence and absence of oxygen. The expression of the fusion protein in E. coli was verified by SOD assays, activity gels and Western blots. The recombinant plasmid was also introduced into Lactococcus lactis, which contains a resident SOD, and into Lactobacillus gasseri, which is devoid of SOD. Transformed lactococci expressed an active SodA fusion protein plus an active hybrid protein composed of subunits of the Lactococcus and the recombinant E. coli enzymes. Transformants of L. gasseri expressed only the fusion SodA protein, which was enzymatically active.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00281598
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