Effect of Escherichia coli wild type or its derivative with high nitrite reductase activity on in vitro ruminal methanogenesis and nitrate/nitrite reduction1

2005 ◽  
Vol 83 (3) ◽  
pp. 644-652 ◽  
Author(s):  
C. Sar ◽  
B. Mwenya ◽  
B. Santoso ◽  
K. Takaura ◽  
R. Morikawa ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Nitrite Reductase ◽  
Reductase Activity ◽  
Wild Type ◽  
Nitrite Reductase Activity

scholarly journals Effect of ruminal administration ofEscherichia coliwild type or a genetically modified strain with enhanced high nitrite reductase activity on methane emission and nitrate toxicity in nitrate-infused sheep

2005 ◽  
Vol 94 (5) ◽  
pp. 691-697 ◽  
Author(s):  
C. Sar ◽  
B. Mwenya ◽  
B. Pen ◽  
K. Takaura ◽  
R. Morikawa ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Body Weight ◽  
Single Dose ◽  
Methane Emission ◽  
Nitrite Reductase ◽  
Reductase Activity ◽  
Wild Type ◽  
E Coli ◽  
Reduction Activity ◽  
Nitrite Reductase Activity

The effects of two kinds ofEscherichia coli(E. coli) strain, wild-typeE. coliW3110 andE. colinir-Ptac, which has enhanced NO2reduction activity, on oral CH4emission and NO3toxicity in NO3-treated sheep were assessed in a respiratory hood system in a 4×6 Youden square design. NO3(1·3g NaNO3/kg0·75body weight) and/orE. colistrains were delivered into the rumen through a fistula as a single dose 30min after the morning meal.Escherichia colicells were inoculated for sheep to provide an initialE. colicell density of optical density at 660nm of 2, which corresponded to 2×1010cells/ml. The six treatments consisted of saline,E. coliW3110,E. colinir-Ptac, NO3, NO3plusE. coliW3110, and NO3plusE. colinir-Ptac. CH4emission from sheep was reduced by the inoculation ofE. coliW3110 orE. colinir-Ptac by 6% and 12%, respectively. NO3markedly inhibited CH4emission from sheep. Compared with sheep given NO3alone, the inoculation ofE. coliW3110 to NO3-infused sheep lessened ruminal and plasma toxic NO2accumulation and blood methaemoglobin production, while keeping ruminal methanogenesis low. Ruminal and plasma toxic NO2accumulation and blood methaemoglobin production in sheep were unaffected by the inoculation ofE. colinir-Ptac. These results suggest that ruminal methanogenesis may be reduced by the inoculation ofE. coliW3110 orE. colinir-Ptac. The inoculation ofE. coliW3110 may abate NO3toxicity when NO3is used to inhibit CH4emission from ruminants.

scholarly journals Nitrite reductase activity of hemoglobin as a systemic nitric oxide generator mechanism to detoxify plasma hemoglobin produced during hemolysis

2008 ◽  
Vol 295 (2) ◽  
pp. H743-H754 ◽  
Author(s):  
Peter C. Minneci ◽  
Katherine J. Deans ◽  
Sruti Shiva ◽  
Huang Zhi ◽  
Steven M. Banks ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitrite Reductase ◽  
Reductase Activity ◽  
Vascular Complications ◽  
Blood Substitutes ◽  
Intravascular Hemolysis ◽  
No Donor ◽  
Nitrite Reductase Activity

Hemoglobin (Hb) potently inactivates the nitric oxide (NO) radical via a dioxygenation reaction forming nitrate (NO3−). This inactivation produces endothelial dysfunction during hemolytic conditions and may contribute to the vascular complications of Hb-based blood substitutes. Hb also functions as a nitrite (NO2−) reductase, converting nitrite into NO as it deoxygenates. We hypothesized that during intravascular hemolysis, nitrite infusions would limit the vasoconstrictive properties of plasma Hb. In a canine model of low- and high-intensity hypotonic intravascular hemolysis, we characterized hemodynamic responses to nitrite infusions. Hemolysis increased systemic and pulmonary arterial pressures and systemic vascular resistance. Hemolysis also inhibited NO-dependent pulmonary and systemic vasodilation by the NO donor sodium nitroprusside. Compared with nitroprusside, nitrite demonstrated unique effects by not only inhibiting hemolysis-associated vasoconstriction but also by potentiating vasodilation at plasma Hb concentrations of <25 μM. We also observed an interaction between plasma Hb levels and nitrite to augment nitroprusside-induced vasodilation of the pulmonary and systemic circulation. This nitrite reductase activity of Hb in vivo was recapitulated in vitro using a mitochondrial NO sensor system. Nitrite infusions may promote NO generation from Hb while maintaining oxygen delivery; this effect could be harnessed to treat hemolytic conditions and to detoxify Hb-based blood substitutes.

ucFabV Requires Functional Reductase Activity to Confer Reduced Triclosan Susceptibility in Escherichia coli

2015 ◽  
Vol 25 (6) ◽  
pp. 394-402 ◽  
Author(s):  
Taylor L. Fischer ◽  
Robert J. White ◽  
Katherine F.K. Mares ◽  
Devin E. Molnau ◽  
Justin J. Donato
Keyword(s):  
Escherichia Coli ◽  
Reductase Activity ◽  
Acid Synthesis ◽  
Temperature Sensitive ◽  
Wild Type ◽  
E Coli ◽  
Enoyl Acp Reductase ◽  
Selection For

<b><i>Background/Aims:</i></b> We previously identified the Triclo1 fosmid in a functional metagenomic selection for clones that increased triclosan tolerance in <i>Escherichia coli</i>. The active enzyme encoded by Triclo1 is ucFabV. Although ucFabV is homologous to FabV from other organisms, ucFabV contains substitutions at key positions that would predict differences in substrate binding. Therefore, a detailed characterization of ucFabV was conducted to link its biochemical activity to its ability to confer reduced triclosan sensitivity. <b><i>Methods:</i></b> ucFabV and a catalytic mutant were purified and used to reduce crotonoyl-CoA in vitro. The mutant and wild-type enzymes were introduced into <i>E. coli</i>, and their ability to confer triclosan tolerance as well as suppress a temperature-sensitive mutant of FabI were measured. <b><i>Results:</i></b> Purified ucFabV, but not the mutant, reduced crotonoyl-CoA in vitro. The wild-type enzyme confers increased triclosan tolerance when introduced into <i>E. coli</i>, whereas the mutant remained susceptible to triclosan<i>. </i>Additionally, wild-type ucFabV, but not the mutant, functionally replaced FabI within living cells. <b><i>Conclusion:</i></b> ucFabV confers increased tolerance through its function as an enoyl-ACP reductase. Furthermore, ucFabV is capable of restoring viability in the presence of compromised FabI, suggesting ucFabV is likely facilitating an alternate step within fatty acid synthesis, bypassing FabI inhibition.

scholarly journals Involvement of the PrrB/PrrA Two-Component System in Nitrite Respiration in Rhodobacter sphaeroides 2.4.3: Evidence for Transcriptional Regulation

2002 ◽  
Vol 184 (13) ◽  
pp. 3521-3529 ◽  
Author(s):  
William P. Laratta ◽  
Peter S. Choi ◽  
Ivan E. Tosques ◽  
James P. Shapleigh
Keyword(s):  
Rhodobacter Sphaeroides ◽  
Nitrite Reductase ◽  
Response Regulator ◽  
Reductase Activity ◽  
Wild Type ◽  
Gene Encoding ◽  
Wild Type Phenotype ◽  
Two Component ◽  
Nitrite Reductase Activity ◽  
Nitrite Respiration

ABSTRACT Rhodobacter sphaeroides strain 2.4.3 is capable of diverse metabolic lifestyles, including denitrification. The regulation of many Rhodobacter genes involved in redox processes is controlled, in part, by the PrrBA two-component sensor-regulator system, where PrrB serves as the sensor kinase and PrrA is the response regulator. Four strains of 2.4.3 carrying mutations within the prrB gene were isolated in a screen for mutants unable to grow anaerobically on medium containing nitrite. Studies revealed that the expression of nirK, the structural gene encoding nitrite reductase, in these strains was significantly decreased compared to its expression in 2.4.3. Disruption of prrA also eliminated the ability to grow both photosynthetically and anaerobically in the dark on nitrite-amended medium. Complementation with prrA restored the wild-type phenotype. The PrrA strain exhibited a severe decrease in both nitrite reductase activity and expression of a nirK-lacZ fusion. Nitrite reductase activity in the PrrA strain could be restored to wild-type levels by using nirK expressed from a heterologous promoter, suggesting that the loss of nitrite reductase activity in the PrrA and PrrB mutants was not due to problems with enzyme assembly or the supply of reductant. Inactivation of prrA had no effect on the expression of the gene encoding NnrR, a transcriptional activator required for the expression of nirK. Inactivation of ccoN, part of the cbb 3-type cytochrome oxidase shown to regulate the kinase activity of PrrB, also caused a significant decrease in both nirK expression and Nir activity. This was unexpected, since PrrA-P accumulates in the ccoN strain. Together, these results demonstrate that PrrBA plays an essential role in the regulation of nirK.

A mutation leading to the total lack of nitrite reductase activity in Escherichia coli K 12

1978 ◽  
Vol 160 (2) ◽  
pp. 225-229 ◽  
Author(s):  
M. Chippaux ◽  
D. Giudici ◽  
A. Abou-Jaoudé ◽  
F. Casse ◽  
M. C. Pascal
Keyword(s):  
Escherichia Coli ◽  
Nitrite Reductase ◽  
Reductase Activity ◽  
Nitrite Reductase Activity ◽  
Total Lack ◽  
K 12

scholarly journals Electron transfer to nitrite reductase of Rhodobacter sphaeroides 2.4.3: examination of cytochromes c 2 and c Y

Microbiology ◽  
2006 ◽  
Vol 152 (5) ◽  
pp. 1479-1488 ◽  
Author(s):  
William P. Laratta ◽  
Michael J. Nanaszko ◽  
James P. Shapleigh
Keyword(s):  
Electron Transfer ◽  
Electron Donor ◽  
Rhodobacter Sphaeroides ◽  
Nitrite Reductase ◽  
Double Mutant ◽  
Reductase Activity ◽  
Nitrite Reduction ◽  
Nitrite Reductase Gene ◽  
Nitrite Reductase Activity

The role of cytochrome c 2, encoded by cycA, and cytochrome c Y, encoded by cycY, in electron transfer to the nitrite reductase of Rhodobacter sphaeroides 2.4.3 was investigated using both in vivo and in vitro approaches. Both cycA and cycY were isolated, sequenced and insertionally inactivated in strain 2.4.3. Deletion of either gene alone had no apparent effect on the ability of R. sphaeroides to reduce nitrite. In a cycA–cycY double mutant, nitrite reduction was largely inhibited. However, the expression of the nitrite reductase gene nirK from a heterologous promoter substantially restored nitrite reductase activity in the double mutant. Using purified protein, a turnover number of 5 s−1 was observed for the oxidation of cytochrome c 2 by nitrite reductase. In contrast, oxidation of c Y only resulted in a turnover of ∼0·1 s−1. The turnover experiments indicate that c 2 is a major electron donor to nitrite reductase but c Y is probably not. Taken together, these results suggest that there is likely an unidentified electron donor, in addition to c 2, that transfers electrons to nitrite reductase, and that the decreased nitrite reductase activity observed in the cycA–cycY double mutant probably results from a change in nirK expression.

scholarly journals Differential Suppression of priA2::kan Phenotypes in Escherichia coli K-12 by Mutations in priA, lexA, and dnaC

Genetics ◽  
1996 ◽  
Vol 143 (1) ◽  
pp. 5-13 ◽  
Author(s):  
Steven J Sandler ◽  
Hardeep S Samra ◽  
Alvin J Clark
Keyword(s):  
Escherichia Coli ◽  
Dna Replication ◽  
Mutant Allele ◽  
Wild Type ◽  
Suppressor Mutations ◽  
Dnab Helicase ◽  
K 12 ◽  
Extragenic Suppressors ◽  
Assembly Activity

Abstract First identified as an essential component of the ϕX174 in vitro DNA replication system, PriA has ATPase, helicase, translocase, and primosome-assembly activities. priA1::kan strains of Escherichia coli are sensitive to UV irradiation, deficient in homologous recombination following transduction, and filamentous. priA2::kan strains have eightfold higher levels of uninduced SOS expression than wild type. We show that (1) priA1::kan strains have eightfold higher levels of uninduced SOS expression, (2) priA2::kan strains are UVS and Rec−, (3) lexA3 suppresses the high basal levels of SOS expression of a priA2::kan strain, and (4) plasmid-encoded priA300 (K230R), a mutant allele retaining only the primosome-assembly activity of priA+, restores both UVR and Rec+ phenotypes to a priA2::kan strain. Finally, we have isolated 17 independent UVR Rec+ revertants of priA2::kan strains that carry extragenic suppressors. All 17 map in the C-terminal half of the dnaC gene. DnaC loads the DnaB helicase onto DNA as a prelude for primosome assembly and DNA replication. We conclude that priA's primosome-assembly activity is essential for DNA repair and recombination and that the dnaC suppressor mutations allow these processes to occur in the absence of priA.

scholarly journals 0099. Nitrite reductase activity during sepsis

2014 ◽  
Vol 2 (S1) ◽  
Author(s):  
V Simon ◽  
A Dyson ◽  
M Minnion ◽  
M Feelisch ◽  
M Singer
Keyword(s):  
Nitrite Reductase ◽  
Reductase Activity ◽  
Nitrite Reductase Activity
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