Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytosine deaminase, encoded by the codA gene in Escherichia coli catalyzes the deamination of cytosine to uracil and ammonia. Regulation of codA expression was studied by determining the level of cytosine deaminase in E. coli K12 grown in various defined media. Addition of either pyrimidine or purine nucleobases to the growth medium caused repressed enzyme levels, whereas growth on a poor nitrogen source such as proline resulted in derepression of cytosine deaminase synthesis. Derepression of codA expression was induced by starvation for either uracil or cytosine nucleotides. Nitrogen control was found to be mediated by the glnLG gene products, and purine repression required a functional purR gene product. Studies with strains harbouring multiple mutations affecting both pyrimidine, purine and nitrogen control revealed that the overall regulation of cytosine deaminase synthesis by the different metabolites is cumulative.
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PMID:Pyrimidine, purine and nitrogen control of cytosine deaminase synthesis in Escherichia coli K 12. Involvement of the glnLG and purR genes in the regulation of codA expression. 267 19

By inserting a lambda placMu bacteriophage into gene glmS encoding glucosamine 6-phosphate synthetase (GlmS), the key enzyme of amino sugar biosynthesis, a nonreverting mutant of Escherichia coli K-12 that was strictly dependent on exogenous N-acetyl-D-glucosamine or D-glucosamine was generated. Analysis of suppressor mutations rendering the mutant independent of amino sugar supply revealed that the catabolic enzyme D-glucosamine-6-phosphate isomerase (deaminase), encoded by gene nagB of the nag operon, was able to fulfill anabolic functions in amino sugar biosynthesis. The suppressor mutants invariably expressed the isomerase constitutively as a result of mutations in nagR, the locus for the repressor of the nag regulon. Suppression was also possible by transformation of glmS mutants with high-copy-number plasmids expressing the gene nagB. Efficient suppression of the glmS lesion, however, required mutations in a second locus, termed glmX, which has been localized to 26.8 min on the standard E. coli K-12 map. Its possible function in nitrogen or cell wall metabolism is discussed.
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PMID:Alternative route for biosynthesis of amino sugars in Escherichia coli K-12 mutants by means of a catabolic isomerase. 268 46

The catabolic L-serine (L-threonine) deaminase of Saccharomyces cerevisiae allows the yeast to grow on media with L-serine or L-threonine as sole nitrogen source. A mutant, cha1 (catabolism of hydroxyamino acids), lacking this enzyme activity has been isolated. We have cloned the CHA1 gene by complementation of a cha1 mutation. Northern analysis showed that CHA1 mRNA has a size of about 1200 ribonucleotides. CHA1 is probably the structural gene for the enzyme; it is an abundant RNA in cells grown with serine and threonine as nitrogen source, whereas it is not detected when cells are grown on ammonium or proline, i.e., the transcription of the CHA1 gene is induced by serine or threonine. Under induced growth conditions haploid ilv1 CHA1 strains do not require isoleucine, i.e., the catabolic deaminase is able to substitute for the biosynthetic threnonine deaminase encoded by the ILV1 gene. We have identified a nuclear, recessive mutation, sil1, that suppresses ilv1 mutations by increased transcription of the CHA1 gene under growth conditions leading to partial induction. The sil1 mutation could exert its effect by increasing the effective pools of the hydroxyamino acids. Alternatively SIL1 may encode a negatively acting regulatory protein for CHA1.
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PMID:Molecular genetics of serine and threonine catabolism in Saccharomyces cerevisiae. 284 Nov 85

Of five amidohydrolase activities subject to nitrogen metabolite repression in Aspergillus nidulans, L-asparaginase shows clearest evidence of also being subject to repression by atmospheric oxygen. Such oxygen repressibility is only evident under nitrogen metabolite derepressed conditions. Asparaginase levels are also considerably elevated by areA300, an altered function allele of the positive acting wide domain regulatory gene areA mediating nitrogen metabolite repression and are drastically reduced by loss of function mutations in areA. A. nidulans has two L-asparaginase enzymes and it has been shown by the use of appropriate mutants that these regulatory effects are exerted on the expression of that specified by the ahrA gene but probably not that specified by the apnA gene.
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PMID:An asparaginase of Aspergillus nidulans is subject to oxygen repression in addition to nitrogen metabolite repression. 304 73

The detrimental effects of excessive Ni on plant growth have been well known for many years. More recent evidence indicates that Ni is required in small amounts for normal plant growth and development. Ni is an essential component of urease in plants and microorganisms. A deficiency of Ni in plants is reported to result in necrotic lesions in leaves in response to toxic accumulations of urea. Urease plays an essential role in mobilization of nitrogenous compounds in plants, a process that is especially important during seed germination and fruit formation when protein reserves are degraded into amino acids. Arginine, an abundant amino acid in plants, when degraded produces urea as a product and urease is needed for urea utilization. Theories of urea formation during allantoin degradation in Glycine max have been recently refuted. In G. max ureides apparently are metabolized via an amidohydrolase reaction with subsequent degradation of ureidoglycine, yielding glyoxylate, NH+4 and CO2. No evidence is available for the formation of urea in this pathway. Nitrogen-fixing symbionts, such as Rhizobium and Bradyrhizobium, contain two known Ni enzymes: urease and hydrogenase. Optimum growth of nodulated legumes and actinorhizal plants may depend on an adequate supply of Ni to meet the requirements of the Ni-requiring enzymes in host plants and endophytes. The seeds of severely Ni-deficient Hordeum are completely inviable, thus providing conclusive evidence for the essentiality of Ni for this species. The evidence indicates that Ni must be added to the list of micronutrient elements generally required by plants.
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PMID:Nickel as a micronutrient element for plants. 307 27

Pseudomonas putida PP3 carrying dehalogenases I and II and Pseudomonas aeruginosa PAU3 carrying dehalogenase I coded for by plasmid pUU2 were able to grow on 2-monochloropropionic acid (2MCPA). Neither strain utilized 2-chloropropionamide (2CPA) as a carbon or nitrogen source for growth. Mutations in both strains to 2Cpa+ phenotypes (designated P. putida PPW3 and P. aeruginosa PAU5, respectively) involved the expression of an acquired 2CPA-amidase activity. The amidase followed by dehalogenase reactions in these strains constituted a novel metabolic pathway for growth on 2CPA. P. putida PPW3 synthesized a constitutive amidase of molecular mass 59 kDa consisting of two identical subunits of 29 kDa. For those amides tested this acquired enzyme was most active against chlorinated aliphatic amides, although substrate affinities (Km) and maximum rates of activity (Vmax) were poor. P. aeruginosa PAU5 acquired a 2Cpa+ phenotype by overproducing the A-amidase normally used by this species to hydrolyse aliphatic amides. The A-amidase had only slight activity towards 2CPA. However, with constitutive synthesis the mutant grew on the chlorinated substrates. Chloroacetamide (CAA) was a toxic substrate analogue for these Pseudomonas strains. A strain resistant to CAA was isolated from P. aeruginosa PAU5 when exposed to 1-10 mM-CAA. This mutant, P. aeruginosa PAU6, synthesized an inducible A-amidase. CAA-resistance depended upon the simultaneous expression of CAA-inducible amidase and dehalogenase activities.
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PMID:A comparative study of acquired amidase activity in Pseudomonas species. 309 6

Pyrimidine metabolism in Pseudomonas fluorescens biotype F, and its ability to grow in liquid culture on pyrimidines and related compounds was investigated. It was found that uracil, uridine, cytosine, cytidine, deoxycytidine, dihydrouracil, dihydrothymine, beta-alanine or beta-aminoisobutyric acid could be utilized by this pseudomonad as a sole nitrogen source. Only uridine, cytidine, beta-alanine, beta-aminoisobutyric acid or ribose were capable of supporting its growth as a sole source of carbon. In solid medium, the pyrimidine analogue 5-fluorouracil or 5-fluorouridine could prevent P. fluorescens biotype F growth at a low concentration while a 20-fold higher concentration of 5-fluorocytosine, 5-fluorodeoxyuridine or 6-azauracil was necessary to block its growth. The pyrimidine salvage enzymes cytosine deaminase, nucleoside hydrolase, uridine phosphorylase, thymidine phosphorylase and cytidine deaminase were assayed. Only cytosine deaminase and nucleoside hydrolase activities could be detected under the assay conditions used. The effect of growth conditions on cytosine deaminase and nucleoside hydrolase levels in the micro-organism was explored. Cytosine deaminase activity was shown to increase if glycerol was substituted for glucose as the sole carbon source or if asparagine replaced (NH4)2SO4 as the sole nitrogen source in each respective medium. In contrast, nucleoside hydrolase activity remained virtually unchanged whether the carbon source in the medium was glucose or glycerol. A decrease in nucleoside hydrolase activity was witnessed when asparagine was present in the medium instead of (NH4)2SO4 as the sole source of nitrogen.
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PMID:Metabolism of pyrimidine bases and nucleosides by Pseudomonas fluorescens biotype F. 314 44

Distribution of acylase in different tissues of nine species of animals was studied. The following types of nitrogen elimination were distinguished: ammoniatelic (fish), uricotelic (birds) and uriotelic (amphibians, mammalians). The enzymic activity was estimated in the tissues of the brain, lung, muscle, liver, kidney, spleen, pancreas, small intestine and blood serum. The acylase activity was found in the kidney, liver and pancreas. Its level in the kidney increases with the animal weight growth, the enzyme activity being observed only in the cortical layer.
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PMID:[Acylase distribution in animal and human tissues]. 318 61

The regulation of nitrile-hydratase biosynthese was studied in Brevibacterium sp R 312. Enzyme biosynthesis was not influenced by any carbon and nitrogen source used in the growth medium. It was, however, repressed by amide and amide analogues. Acetamide repressed nitrile-hydratase biosynthesis and induced the wide-spectrum amidase. Therefore, it appeared reasonable to hypothesize a single repressor gene for the nitrile-hydratase/wide-spectrum amidase system.
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PMID:Regulation of nitrile-hydratase synthesis in a Brevibacterium species. 372 77

Proteus rettgeri and Escherichia coli W were shown to express structurally different penicillin G acylases. The enzymes had similar substrate specificity but differed in molecular weight, isoelectric point, and electrophoretic mobility in polyacrylamide gels and did not antigenically cross-react. When the organisms were subjected to environmental conditions which made expression of this enzyme essential for growth, spontaneous mutants were isolated that used different amides as the only source of nitrogen. These mutants acquired the ability to use amides for growth by deregulating the penicillin G acylase and by their evolution to novel substrate specificities. The enzymes expressed by mutants isolated from each genus appeared to have evolved in parallel since each acylase attained similar new substrate specificities when the organisms were subjected to identical selection pressure.
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PMID:Experimental evolution of penicillin G acylases from Escherichia coli and Proteus rettgeri. 389


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