Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.7.1.4 (nitrite reductase)
1,847 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Seventeen strains of the new species Bacillus azotoformans were isolated by enrichment culture in peptone broth inoculated with pasteurized soil and then incubated under N2O at 32 degrees C. The bacterium is a Gram-negative rod, motile with peritrichous flagella, which produces oval spores without exosporia in swollen sporangia. However, the cells have thick walls, mesosomes, and persistent septa characteristic of Gram-positive bacteria. The bacterium lacks fermentative activity, does not attack carbohydrates, has complex growth requirements, and will grow anaerobically only if one of the following electron acceptors is present: NO3-, NO2-, N2O, S4O6--, or fumarate. Nitrate, nitrite, and nitrous oxide are denitrified with the production of N2. The microorganism is mesophilic, gives a positive oxidase reaction, synthesizes a type c cytochrome, and does not hydrolyse gelatin, starch, or "Tween 80." Poly-beta-hydroxybutyric acid is snythesized when the bacterium is grown in a medium containing DL-3-hydroxybutyrate. The following enzymes are present: nitrate reductase A, respiratory nitrite reductase, tetrathionate and fumarate reductases, and L-glutamate dehydrogenase. The following enzymes are absent: thiosulfate reductase, urease, lecithinase, arginine dihydrolase, phenylalanine deaminase, and catalase. For the 17 strains, the mean value of the G = C percent of the DNA is 39.8 +/- 1.2. All the strains are highly similar.
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PMID:[Morphological, physiological and taxonomic studies of Bacillus azotoformans]. 65 12

The strains were isolated from soil by enrichment in a liquid minimal medium containing ethanol, acetate, succinate, L-malate or tartrate, under an N2O atmosphere at 32 degrees C. All fourteen strains can use the following 25 sources of carbon and energy under aerobic conditions: glycerate, ethanol, propanol, acetate, butyrate, malonate, succinate, glutarate, sebacate, glycollate, L-lactate, D-lactate, L-malate, DL-3-hydroxybutyrate, pyruvate, fumarate, itaconate, mesaconate, crotonate, L-alpha-alanine, D-alpha-alanine, L-leucine, asparagine, L-tyrosine, and L-proline. They hydrolyze Tween 80 but not gelatin. Nitrate is used as nitrogen source. Nitrate reductase A and respiratory nitrite reductase are present. Four of the strains are clearly and easily distinguishable from the others on the basis of six characters: special morphology of colonies; in ability to use isovalerate and DL-valine, inability to use glucose, absence of exocellular amylase, and high level of metapyrocatechase. Their G + C content is 66-67%. One of the strains is distinct from the others by the yellow pigmentation of its colonies, its ability to use D-glucuronate, trehalose, D-sorbitol and citraconate, ability to grow at 4 degrees but not at 40 degrees, and a lower G + C content: 63%. One strain accumulates poly-beta-hydroxybutyrate. This work confirms the well-known, wide variability of the bacteria belonging to the P. stutzeri group. Denitrification by two of the strains was quantitatively studied using cell suspensions. Cells from NO-3-containing anaerobic cultures reduce NO-3, NO-2 and NO to N2O and N2; they reduce slowly N2O to N2. Cells grown in anaerobic cultures under N2O also reduce NO-3, NO-2 and NO to N2O and N2 but they reduce N2O rapidly to N2.
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PMID:[Study of 14 denitrifying soil bacteria of the "pseudomonas stutzeri" group isolated by enrichment culture in the presence of nitrous oxide (author's transl)]. 86 7

The described bacterium was isolated by enrichment culture in peptone broth inoculated with garden soil, pasteurized and then put to incubate under N2O at 32 degrees. It is a Gram-negative rod, motile with peritrichous flagella, and producing oval spores without exosporium in swollen sporangia. However, cells have the thick walls, mesosomes and persistant septa characteristic of Gram-positive bacteria. It lacks fermentative activity, does not attack carbohydrates, has complex growth requirements, and will grow anaerobically only if one of the following electron acceptors is present: NO3, NO2, N2O, S4O6, and fumarate. Nitrate, nitrite, and nitrous oxide are denitrified with production of N2. The microorganism is mesophilic, gives a positive oxidase reaction, synthesizes a type of c cytochrome, and does not hydrolyse gelatin, starch nor "Tween 80". The following enzymes are present: nitrate reductase A, respiratory nitrite reductase, tetrathionate and fumarate reductases, L-glutamate dehydrogenase, and superoxide dismutase. The following enzymes are absent: thiosulfate reductase, urease, lecithinase, arginine dihydrolase, L-alanine dehydrogenase, phenylalanine desaminase, and catalase. The GC% of its DNA is 39. The bacterium described can be considered to be a new species. We propose the name Bacillus azotoformans n. sp.
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PMID:[A new, sporulating, denitrifying, mesophilic bacterium: Bacillus azotoformans N. SP. (author's transl)]. 102 Aug 72

The nirA gene of Aspergillus nidulans and the nit-4 gene of Neurospora crassa appear to be equivalent pathway-specific regulatory genes which mediate nitrate induction of nitrate reductase and nitrite reductase (NR and NiR) activities. We have transformed the nit-4 wild-type (wt) gene into the A. nidulans loss-of-function (pleiotropic negative) nirA 1 mutant strain. The nit-4 gene was found to complement the nirA 1 mutation, thus permitting the nirA 1 mutant strain to grow on nitrate or nitrite as the sole source of nitrogen. Integration of the nit-4 gene in transformants appears to have occurred at a number of 'ectopic', i.e. non-nirA, sites. Nitrate is required for the induction of NR activity in nit-4-transformed strains whilst NR production remains markedly subject to nitrogen-metabolite repression. However, NR levels are modestly higher than wt under all growth conditions.
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PMID:Heterologous expression and regulation of the Neurospora crassa nit-4 pathway-specific regulatory gene for nitrate assimilation in Aspergillus nidulans. 182 47

Expression of nitrite uptake and nitrite reductase activities has been studied in Chlamydomonas reinhardtii under different nutritional conditions. Both activities were expressed at a low level in derepressed cells (with no nitrogen source) and at a high level in induced cells (with nitrate or nitrite). Nitrate was required for both activities to be maximally expressed. Ammonium-grown cells did not show nitrite uptake capability and had a basal nitrite reductase activity. Nitrite uptake but not nitrite reductase levels decreased very significantly in nitrate-induced cells subject to cycloheximide treatment, which suggests that protein(s) involved in the uptake are under a rapid turnover. Nitrite uptake expression was strongly inhibited by the presence of the glutamine synthetase inhibitor L-methionine-D,L-sulfoximine under either derepression or induction conditions, whereas that of nitrite reductase was not affected under the same conditions. Our results indicate that nitrite uptake expression is regulated primarily by ammonium, and that of nitrite reductase by both ammonium and ammonium derivative(s).
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PMID:Regulation of nitrite uptake and nitrite reductase expression in Chlamydomonas reinhardtii. 204 80

Under anaerobic circumstances in the presence of nitrate Paracoccus denitrificans is able to denitrify. The properties of the reductases involved in nitrate reductase, nitrite reductase, nitric oxide reductase, and nitrous oxide reductase are described. For that purpose not only the properties of the enzymes of P. denitrificans are considered but also those from Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas stutzeri. Nitrate reductase consists of three subunits: the alpha subunit contains the molybdenum cofactor, the beta subunit contains the iron sulfur clusters, and the gamma subunit is a special cytochrome b. Nitrate is reduced at the cytoplasmic side of the membrane and evidence for the presence of a nitrate-nitrite antiporter is presented. Electron flow is from ubiquinol via the specific cytochrome b to the nitrate reductase. Nitrite reductase (which is identical to cytochrome cd1) and nitrous oxide reductase are periplasmic proteins. Nitric oxide reductase is a membrane-bound enzyme. The bc1 complex is involved in electron flow to these reductases and the whole reaction takes place at the periplasmic side of the membrane. It is now firmly established that NO is an obligatory intermediate between nitrite and nitrous oxide. Nitrous oxide reductase is a multi-copper protein. A large number of genes is involved in the acquisition of molybdenum and copper, the formation of the molybdenum cofactor, and the insertion of the metals. It is estimated that at least 40 genes are involved in the process of denitrification. The control of the expression of these genes in P. denitrificans is totally unknown. As an example of such complex regulatory systems the function of the fnr, narX, and narL gene products in the expression of nitrate reductase in E. coli is described. The control of the effects of oxygen on the reduction of nitrate, nitrite, and nitrous oxide are discussed. Oxygen inhibits reduction of nitrate by prevention of nitrate uptake in the cell. In the case of nitrite and nitrous oxide a competition between reductases and oxidases for a limited supply of electrons from primary dehydrogenases seems to play an important role. Under some circumstances NO formed from nitrite may inhibit oxidases, resulting in a redistribution of electron flow from oxygen to nitrite. P. denitrificans contains three main oxidases: cytochrome aa3, cytochrome o, and cytochrome co. Cytochrome o is proton translocating and receives its electrons from ubiquinol. Some properties of cytochrome co, which receives its electrons from cytochrome c, are reported.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Metabolic regulation including anaerobic metabolism in Paracoccus denitrificans. 205 Jun 53

Nitrate transport and its regulation by oxygen was studied in denitrifying halophilic Pseudomonas stutzeri, strain Zobell, and a Tn-5 transposon nitrite reductase mutant of this organism. The rate of nitrate transport was found to be 130 nanomoles nitrate min-1 mg protein-1 and 150 nanomoles nitrate min-1 mg protein-1 in the wildtype and the nitrite reductase mutant respectively as compared to 26.4 nanomoles nitrate min-1 mg protein-1 in a non-halophilic Pseudomonas stutzeri. Asparagine was found to be the best energy source for nitrate uptake. The ratio of nitrate import to nitrite export was established by measuring extracellular nitrate and nitrite concentrations using HPLC/UV analysis. There was a 1.3:1 (NO3-/NO2-) exchange. High concentrations of nitrate during growth was found to have a negative effect on nitrite metabolism. Oxygen exerted an inhibitory effect on nitrate uptake which was reversible and more pronounced in cells grown on low concentrations of nitrate compared to cells grown at high concentrations of nitrate.
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PMID:Regulation and energization of nitrate transport in a halophilic Pseudomonas stutzeri. 215 8

Nitrate and nitrite was reduced by Escherichia coli E4 in a L-lactate (5 mM) limited culture in a chemostat operated at dissolved oxygen concentrations corresponding to 90-100% air saturation. Nitrate reductase and nitrite reductase activity was regulated by the growth rate, and oxygen and nitrate concentrations. At a low growth rate (0.11 h-1) nitrate and nitrite reductase activities of 200 nmol.mg-1 protein.min-1 and 250 nmol.mg-1 protein.min-1 were measured, respectively. At a high growth rate (0.55 h-1) both enzyme activities were considerably lower (25 and 12 nmol mg-1.protein.min-1). The steady state nitrite concentration in the chemostat was controlled by the combined action of the nitrate and nitrite reductase. Both nitrate and nitrite reductase activity were inversely proportional to the growth rate. The nitrite reductase activity decreased faster with growth rate than the nitrate reductase. The chemostat biomass concentration of E. coli E4, with ammonium either solely or combined with nitrate as a source of nitrogen, remained constant throughout all growth rates and was not affected by nitrite concentrations. Contrary to batch, E. coli E4 was able to grow in continuous cultures on nitrate as the sole source of nitrogen. When cultivated with nitrate as the sole source of nitrogen the chemostat biomass concentration is related to the activity of nitrate and nitrite reductase and hence, inversely proportional to growth rate.
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PMID:Aerobic nitrate and nitrite reduction in continuous cultures of Escherichia coli E4. 219 29

Propionibacterium acnes P13 was isolated from human feces. The bacterium produced a particulate nitrate reductase and a soluble nitrite reductase when grown with nitrate or nitrite. Reduced viologen dyes were the preferred electron donors for both enzymes. Nitrous oxide reductase was never detected. Specific growth rates were increased by nitrate during growth in batch culture. Culture pH strongly influenced the products of dissimilatory nitrate reduction. Nitrate was principally converted to nitrite at alkaline pH, whereas nitrous oxide was the major product of nitrate reduction when the bacteria were grown at pH 6.0. Growth yields were increased by nitrate in electron acceptor-limited chemostats, where nitrate was reduced to nitrite, showing that dissimilatory nitrate reduction was an energetically favorable process in P. acnes. Nitrate had little effect on the amounts of fermentation products formed, but molar ratios of acetate to propionate were higher in the nitrate chemostats. Low concentrations of nitrite (ca. 0.2 mM) inhibited growth of P. acnes in batch culture. The nitrite was slowly reduced to nitrous oxide, enabling growth to occur, suggesting that denitrification functions as a detoxification mechanism.
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PMID:Dissimilatory nitrate reduction by Propionibacterium acnes. 262 64

We have examined the reactivity of the purified component proteins of Azotobacter vinelandii nitrogenase (Av1 and Av2) toward nitrate and nitrite. Nitrate has no effect on H2 evolution or C2H2 reduction by nitrogenase and thus is neither a substrate nor an inhibitor. Nitrite dramatically inhibits H2 evolution. This inhibition has two components, one irreversible and one reversible upon addition of CO. The irreversible inhibition is due to nitrite inactivation of the Fe protein. The rate of this inactivation is greatly enhanced by addition of MgATP, suggesting the [4Fe-4S] cluster is the site of nitrite attack. The reversible inhibition does not represent an inhibition of electron flow but rather a diversion of electrons away from H2 evolution and into the six-electron reduction of nitrite to ammonia. Thus, nitrogenase functions as a nitrite reductase.
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PMID:Nitrite, a new substrate for nitrogenase. 271 24


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