Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.3.4.6 (urease)
 7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Laboratory experiments were conducted to determine the effect of 32 pesticides applied at 2 levels on populations of microorganisms, activities of urease, dehydrogenase, phosphatase and nitrogenase in a clay loam incubated for 1 week. Results indicated that a decrease in bacterial number was observed with thiram for 2 days and stimulation with chlorpyrifos after 7 days. Some fungicides and fumigants inhibited fungal numbers for 2 days. The recovery was rapid and stimulatory effects on microbial numbers were evident in many samples. None of the pesticides inhibited soil urease drastically. Formazan formation was not suppressed vigorously by the treatments. With the exception of DD and Vorlex at a high level, none of the treatments inhibited phosphatase in the hydrolysis of p-nitrophenyl disodium orthophosphate. A temporary decrease in nitrogenase activity in acetylene (C2H2) reduction was observed with many pesticides. The low amount of pesticides applied to the clay loam is unlikely to have detrimental effects on soil microbes and the enzymes important to soil fertility.
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PMID:Effects of pesticides on activities of enzymes and microorganisms in a clay soil. 626 39

The specific activity of urease, nitrogenase, hialuronidase and neuraminidase in Y. pseudotuberculosis grown in different culture media and at different temperature has been studied. These enzymes have been found capable of functioning at both relatively low (2-8 degrees C) and high (37 degrees C) temperatures. The thermoadaptive properties of Y. pseudotuberculosis within a wide range of temperatures are ensured by the constant presence of isoenzymes, functioning only at low temperatures or only at high temperatures, in the microbial cells. Low temperature in combination with a definite culture medium triggers the activity of certain enzymatic systems, which explains, to some extent, the biochemical mechanisms of the psychrophilic properties of Y. pseudotuberculosis.
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PMID:[Fermentative mechanisms of the psychrophilicity of Yersinia tuberculosis]. 636 42

A microaerophilic nitrogen-fixing bacterium was isolated from surface-sterilized roots of Spartina alterniflora Loisel growing in a Nova Scotian salt marsh. It is a small curved rod and is motile with a single polar flagellum. Metabolism is respiratory. Organic and amino acids, but not carbohydrates, serve as carbon and energy sources. The guanine + cytosine content of its deoxyribonucleic acid is 32.1 +/- 1.0 mol%. Based upon morphological and biochemical characteristics this organism is assigned to the genus Camphlobacter Sebald and Veron 1963. It is distinguishable from other campylobacters by the presence of nitrogenase and urease, by the production of pigment from tryptophan, and by a combination of other biochemical traits. The association of this organism with plant roots further distinguishes it from other campylobacters which commonly inhabit animal, including human, tissues.
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PMID:Isolation of a nitrogen-fixing Campylobacter species from the roots of Spartina alterniflora Loisel. 693 66

Complex metalloenzymes (e.g., nitrogenase, hydrogenase, urease) are synthesized starting from the apoprotein via several intermediates by the action of accessory proteins. The isolation and biochemical characterization of such intermediates is hampered by their low abundance and their lability. Here we describe a technique for efficient single-step purification of a hydrogenase precursor under mild conditions using a N-terminal Strep-tag II affinity peptide and a novel StrepTactin Sepharose matrix. The tag was fused to the large subunit of [NiFe] hydrogenase 3 (HycE) of Escherichia coli. No significant influence of the affinity peptide on maturation or activity of the protein was observed when the modified gene was integrated into the chromosome by homologous recombination. A tagged nickel-free precursor form of HycE bound quantitatively to a recombinant StrepTactin Sepharose column. More than 90% pure subunit could be obtained after elution with desthiobiotin. The procedure was shown to be more efficient than purification by immobilized metal affinity chromatography using a N-terminal His-tag. General advantages of the novel Strep-tag II affinity purification especially for applications with metalloenzymes are discussed.
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PMID:Strep-tag II affinity purification: an approach to study intermediates of metalloenzyme biosynthesis. 960 45

The phototrophic nonsulfur purple bacterium Rhodobacter capsulatus can use urea as a sole source of nitrogen. Three transposon Tn5-induced mutations (Xan-9, Xan-10, and Xan-19), which led to a Ure(-) phenotype, were mapped to the ureF and ureC genes, whereas two other Tn5 insertions (Xan-20 and Xan-22) were located within the ntrC and ntrB genes, respectively. As in Klebsiella aerogenes and other bacteria, the genes encoding urease (ureABC) and the genes required for assembly of the nickel metallocenter (ureD and ureEFG) are clustered in R. capsulatus (ureDABC-orf136-ureEFG). No homologues of Orf136 were found in the databases, and mutational analysis demonstrated that orf136 is not essential for urease activity or growth on urea. Analysis of a ureDA-lacZ fusion showed that maximum expression of the ure genes occurred under nitrogen-limiting conditions (e.g., serine or urea as the sole nitrogen source), but ure gene expression was not substrate (urea) inducible. Expression of the ure genes was strictly dependent on NtrC, whereas sigma(54) was not essential for urease activity. Expression of the ure genes was lower (by a factor of 3.5) in the presence of ammonium than under nitrogen-limiting conditions, but significant transcription was also observed in the presence of ammonium, approximately 10-fold higher than in an ntrC mutant background. Thus, ure gene expression in the presence of ammonium also requires NtrC. Footprint analyses demonstrated binding of NtrC to tandem binding sites upstream of the ureD promoter. Phosphorylation of NtrC increased DNA binding by at least eightfold. Although urea is effectively used as a nitrogen source in an NtrC-dependent manner, nitrogenase activity was not repressed by urea.
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PMID:Urea utilization in the phototrophic bacterium Rhodobacter capsulatus is regulated by the transcriptional activator NtrC. 1113 58

Moderate levels of urease activity (ca. 300 mU mg(-1)) were detected in Rhizobium leguminosarum bv. viciae UPM791 vegetative cells. This activity did not require urea for induction and was partially repressed by the addition of ammonium into the medium. Lower levels of urease activity (ca. 100 mU mg(-1)) were detected also in pea bacteroids. A DNA region of ca. 9 kb containing the urease structural genes ( ureA, ureB and ureC), accessory genes ( ureD, ureE, ureF, and ureG), and five additional ORFs ( orf83, orf135, orf207, orf223, and orf287) encoding proteins of unknown function was sequenced. Three of these ORFs ( orf83, orf135 and orf207) have a homologous counterpart in a gene cluster from Sinorhizobium meliloti, reported to be involved in urease and hydrogenase activities. R. leguminosarum mutant strains carrying Tn 5 insertions within this region exhibited a urease-negative phenotype, but induced wild-type levels of hydrogenase and nitrogenase activities in bacteroids. orf287 encodes a potential transmembrane protein with a C-terminal GGDEF domain. A mutant affected in orf287 exhibited normal levels of urease activity in culture cells. Experiments aimed at cross-complementing Ni-binding proteins required for urease and hydrogenase synthesis (UreE and HypB, respectively) indicated that these two proteins are not functionally interchangeable in R. leguminosarum.
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PMID:Characterization of the urease gene cluster from Rhizobium leguminosarum bv. viciae. 1188 82

One-half of the available protein structures contain metals, explaining their roles as essential trace elements. Metals are also critical in many aspects of nucleic acid biochemistry. This prologue briefly introduces the fifth of the Thematic Series on Metals in Biology, which began in the Journal of Biological Chemistry in 2009. The five minireviews in this 2013 series deal with the molybdenum prosthetic group (a pterin known as Moco); the biosynthesis of the "M-cluster" molybdenum prosthetic group of nitrogenase; the biosynthesis of the nickel-based metallocenter of the enzyme urease; several of the processing, transport, and medical aspects of cobalamins; and the growing roles of heme sensor proteins.
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PMID:Thematic minireview series: metals in biology 2013. 2353 20

Azotobacter vinelandii is a widely studied model diazotrophic (nitrogen-fixing) bacterium and also an obligate aerobe, differentiating it from many other diazotrophs that require environments low in oxygen for the function of the nitrogenase. As a free-living bacterium, A. vinelandii has evolved enzymes and transporters to minimize the loss of fixed nitrogen to the surrounding environment. In this study, we pursued efforts to target specific enzymes and further developed screens to identify individual colonies of A. vinelandii producing elevated levels of extracellular nitrogen. Targeted deletions were done to convert urea into a terminal product by disrupting the urease genes that influence the ability of A. vinelandii to recycle the urea nitrogen within the cell. Construction of a nitrogen biosensor strain was done to rapidly screen several thousand colonies disrupted by transposon insertional mutagenesis to identify strains with increased extracellular nitrogen production. Several disruptions were identified in the ammonium transporter gene amtB that resulted in the production of sufficient levels of extracellular nitrogen to support the growth of the biosensor strain. Further studies substituting the biosensor strain with the green alga Chlorella sorokiniana confirmed that levels of nitrogen produced were sufficient to support the growth of this organism when the medium was supplemented with sufficient sucrose to support the growth of the A. vinelandii in coculture. The nature and quantities of nitrogen released by urease and amtB disruptions were further compared to strains reported in previous efforts that altered the nifLA regulatory system to produce elevated levels of ammonium. These results reveal alternative approaches that can be used in various combinations to yield new strains that might have further application in biofertilizer schemes.
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PMID:Gene Deletions Resulting in Increased Nitrogen Release by Azotobacter vinelandii: Application of a Novel Nitrogen Biosensor. 2588 77

Nitrogen (N) is a primary limiting nutrient for bacterial growth and productivity in the ocean. To better understand bacterial community and their N utilization strategy in different N regimes of the ocean, we examined bacterial diversity, diazotrophic diversity, and N utilization gene expressions in the northwestern Pacific Ocean (NWPO) using a combination of high-throughput sequencing and real-time qPCR methods. 521 and 204 different operational taxonomic units (OTUs) were identified in the 16s rRNA and nifH libraries from nine surface samples. Of the 16s rRNA gene OTUs, 11.9% were observed in all samples while 3.5 and 15.9% were detected only in N-sufficient and N-deficient samples. Proteobacteria, Cyanobacteria and Bacteroidetes dominated the bacterial community. Prochlorococcus and Pseudoalteromonas were the most abundant at the genus level in N-deficient regimes, while SAR86, Synechococcus and SAR92 were predominant in the Kuroshio-Oyashio confluence region. The distribution of the nifH gene presented great divergence among sampling stations: Cyanobacterium_UCYN-A dominated the N-deficient stations, while clusters related to the Alpha-, Beta-, and Gamma-Proteobacteria were abundant in other stations. Temperature was the main factor that determined bacterial community structure and diversity while concentration of NOX-N was significantly correlated with structure and distribution of N2-fixing microorganisms. Expression of the ammonium transporter was much higher than that of urea transporter subunit A (urtA) and ferredoxin-nitrate reductase, while urtA had an increased expression in N-deficient surface water. The predicted ammonium transporter and ammonium assimilation enzymes were most abundant in surface samples while urease and nitrogenase were more abundant in the N-deficient regions. These findings underscore the fact that marine bacteria have evolved diverse N utilization strategies to adapt to different N habitats, and that urea metabolism is of vital ecological importance in N-deficient regimes.
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PMID:Bacterial Diversity and Nitrogen Utilization Strategies in the Upper Layer of the Northwestern Pacific Ocean. 2992 38

Azotobacters have been used as biofertilizer since more than a century. Azotobacters fix nitrogen aerobically, elaborate plant hormones, solubilize phosphates and also suppress phytopathogens or reduce their deleterious effect. Application of wild type Azotobacters results in better yield of cereals like corn, wheat, oat, barley, rice, pearl millet and sorghum, of oil seeds like mustard and sunflower, of vegetable crops like tomato, eggplant, carrot, chillies, onion, potato, beans and sugar beet, of fruits like mango and sugar cane, of fiber crops like jute and cotton and of tree like oak. In addition to the structural genes of the enzyme nitrogenase and of other accessory proteins, A. vinelandii chromosomes contain the regulatory genes nifL and nifA. NifA must bind upstream of the promoters of all nif operons for enabling their expression. NifL on activation by oxygen or ammonium, interacts with NifA and neutralizes it. Nitrogen fixation has been enhanced by deletion of nifL and by bringing nifA under the control of a constitutive promoter, resulting in a strain that continues to fix nitrogen in presence of urea fertilizer. Additional copies of nifH (the gene for the Fe-protein of nitrogenase) have been introduced into A. vinelandii, thereby augmenting nitrogen fixation. The urease gene complex ureABC has been deleted, the ammonia transport gene amtB has been disrupted and the expression of the glutamine synthase gene has been regulated to enhance urea and ammonia excretion. Gluconic acid has been produced by introducing the glucose dehydrogenase gene, resulting in enhanced solubilization of phosphate.
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PMID:Azotobacters as biofertilizer. 3149 3


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