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Query: UMLS:C0519030 (Klebsiella)
 21,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The degradation of agmatine to succinate by Klebsiella aerogenes occurs in five steps. The enzyme catalyzing the first step, agmatinase, is induced by agmatine. The enzymes catalyzing the second and third steps, putrescine aminotransferase and 4-aminobutyraldehyde dehydrogenase, are induced by putrescine and also by their product, 4-aminobutyrate. The enzymes catalyzing the fourth and fifth steps, 4-aminobutyrate aminotransferase and succinate semialdehyde dehydrogenase, are induced by 4-aminobutyrate. This compound also serves as gratuitous inducer of the catabolic acetylornithine aminotransferase. The formation of the enzymes responsible for agmatine degradation is regulated not only by induction, but also by catabolite repression and activation by glutamine synthetase.
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PMID:Enzymes of agmatine degradation and the control of their synthesis in Klebsiella aerogenes. 3 12

We have partially characterized the biochemical parameters of glutamine synthetase from Klebsiella pneumoniae and have shown that the differential affinity of adenylylated and unadenylylated glutamine synthetase for adenosine diphosphate provides a convenient means of determining the adenylylation state. Using this assay procedure, we examined the relationship between the adenylylation state and the expression of other genes involved in nitrogen assimilation. We observed no correlation between the adenylylation state and the expression of histidase, glutamine synthetase, glutamate synthase, glutamate dehydrogenase, and urease in aerobic cultures.
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PMID:Relation between the adenylylation state of glutamine synthetase and the expression of other genes involved in nitrogen metabolism. 3 15

The intracellular levels of glutamine synthetase (GS) in Anacystis nidulans grown under different conditions were determined using a whole-cell assay. Nitrate-grown cells have 64% more GS than cells grown in ammonium sulfate. Nitrogen starvation does not affect GS levels appreciably. Incubation of nitrate-grown cells with ammonium sulfate does not change the ratio of gamma-glutamyl transferase activities stimulated by Mg2+ and Mn2+ ions. An in vitro test of adenylylation indicates that algae do not have an endogenous adenylyl transferase (ATase) and that algal GS is not adenylylatable by the Klebsiella aerogenes ATase. Some characteristics of the GS-membrane complex were determined by centrifugation of the complex under varying conditions of pH and ionic strength. In this way, it was shown that acid pH (4.5) stabilizes the complex and high ionic strength tends to solubilize the enzyme. A simple partial purification of GS (89-fold) was developed based on the sedimentation properties of GS.
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PMID:Distinctive properties of glutamine synthetase from the cyanobacterium Anacystis nidulans. 3 92

Previous studies have implicated glutamine synthetase (L-glutamate:ammonia ligase [adenosine diphosphate for-ing], EC 6.6.1.2) as a major controlling element of the nitrogen fixation (nif) genes in Klebsiella pneumoniae. We report here the isolation of a new class of K. pneumoniae mutants which exhibit altered patterns of nif and hut (histidine utlization) regulation. The expression of nif in these mutants, which were isolated as Gln+ (glutamine nonrequiring) revertants of a particular glnA mutation, is extremely sensitive to ammonia repression. These mutants have a Nif- Hut- phenotype at external ammonia concentrations at which wild-type strains are Nif+ Hut+. On the other hand, these mutants can be fully derepressed for nif at very low ammonia concentrations. We adopted the nomenclature "GlnR- (Nif- Hut-)" to facilitate discussion of the phenotype of these mutant strains. The mutations in these strains which confer the GlnR- phenotype map at or near glnA, the structural gene for glutamine synthetase.
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PMID:Glutamine synthetase mutations which affect expression of nitrogen fixation genes in Klebsiella pneumoniae. 4 Sep 60

Tyramine oxidase in Klebsiella aerogenes is highly specific for tyramine, dopamine, octopamine, and norepinephrine, and its synthesis is induced specifically by these compounds. The enzyme is present in a membrane-bound form. The Km value for tyramine is 9 X 10(-4) M. Tyramine oxidase synthesis was subjected to catabolite repression by glucose in the presence of ammonium salts. Addition of cyclic adenosine 3',5'-monophosphate (cAMP) overcame the catabolite repression. A mutant strain, K711, which can produce a high level of beta-galactosidase in the presence of glucose and ammonium chloride, can also synthesize tyramine oxidase and histidase in the presence of inducer in glucose ammonium medium. Catabolite repression of tyramine oxidase synthesis was relieved when the cells were grown under conditions of nitrogen limitation, whereas beta-galactosidase was strongly repressed under these conditions. A cAMP-requiring mutant, MK54, synthesized tyramine oxidase rapidly when tyramine was used as the sole source of nitrogen in the absence of cAMP. However, a glutamine synthetase-constitutive mutant, MK94, failed to synthesize tyramine oxidase in the presence of glucose and ammonium chloride, although it synthesized histidase rapidly under these conditions. These results suggest that catabolite repression of tyramine oxidase synthesis in K. aerogenes is regulated by the intracellular level of cAMP and an unknown cytoplasmic factor that acts independently of cAMP and is formed under conditions of nitrogen limitation.
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PMID:Regulation of tyramine oxidase synthesis in Klebsiella aerogenes. 17 74

Mutations at two sites of the Klebsiella aerogenes chromosome, unlinked by transduction with phages PW52 and P1, result in the lack of enzymatically active glutamine synthetase. A mutation in the glnB site leads to a marked decrease in the formation of an apparently normal enzyme. Some of the mutations in the glnA site lead to the production of enzymatically inactive material capable of reacting with anti-glutamine synthetase serum. The revertant of a glnA mutant was found to produce a glutamine synthetase with less activity and less stability to heat than the enzyme of the wild type. These results locate the structural gene to the production of enzymatically inactive glutamine synthetase antigen, not subject to repression by exogenously added ammonia. This observation suggests that glutamine synthetase is itself involved in the regulation of the synthesis of glutamine synthetase.
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PMID:Identification of the structural gene for glutamine synthetase in Klebsiella aerogenes. 23 38

Mutations at two sites, glnA and glnB, of the Klebsiella aerogenes chromosome result in the loss of glutamine synthetase. The locations of these sites on the chromosome were established by complementation by episomes of Escherichia coli and by determination of their linkage to other genetic sites by transduction with phage P1. The glnB gene is located at a position corresponding to 48 min on the Taylor map of the E. coli chromosome; it is linked to tryA, nadB, and GUA. The glnA gene is at a position corresponding to 77 min on the Taylor map and is linked to rha and metB; it is also closely linked to rbs, located in E. coli at 74 min, indicating a difference in this chromosomal region between E. coli and K. aerogenes. Mutations in the glnA site can also lead to nonrepressible synthesis of active glutamine synthetase. The examination of the fine genetic structure of glnA revealed that one such mutation is located between two mutations leading to the loss of enzymatic activity. This result, together with evidence that the structural gene for glutamine synthetase is at glnA, suggests that glutamine synthetase controls expression of its own structural gene by repression.
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PMID:Genetic control of glutamine synthetase in Klebiella aerogenes. 23 39

Ammonia-nitrogen-limited continuous cultures of Escherichia coli and Klebsiella aerogenes contain induced levels of glutamine synthetase that is deadenylyated (i.e., fully active). In the presence of excess ammonia or glutamate in glucose-limited cultures of E. coli, glutamine synthetase is repressed and adenylylated (inactive). The average state of adenylylation (n) is a linear function of the specific growth rate. At low specific growth rates, glutamine synthetase is adenylylated; as the specific growth rate increases, n decreases, approaching 0 to 2 at rapid growth rates. The average state of adenylylation correlates well with the intracellular concentrations and ratios of alpha-ketoglutarate and glutamine, which are key effectors in the adenylylation-deadenylylation systems. E. coli and K. aerogenes differ markedly in their growth yields, growth rates, and enzymatic composition during nitrogen limitation. The data suggest that, unlike K. aerogenes, E. coli W uses glutamate dehydrogenase to incorporate ammonia during nitrogen limitation. In E. coli, glutamate dehydrogenase is progressively induced during nitrogen limitation when mu (growth rate) approaches mumax. In contrast, in K. aerogenes glutamate dehydrogenase is repressed during nitrogen limitation, whereas glutamate synthase, an alternative supplier of glutamate to the cell, is induced. Data are presented that support the regulatory schemes proposed for the control of glutamine synthetase activity by induction-repression phenomena and adenylylation-deadenylylation reaction. We propose that the intracellular ratio of alpha-ketoglutarate to glutamine may be the most important physiological parameter in determining the activity of glutamine synthetase.
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PMID:Regulation of nitrogen metabolism in Escherichia coli and Klebsiella aerogenes: studies with the continuous-culture technique. 23 54

The regulation of glutamate dehydrogenase (EC 1.4.1.4), glutamine synthetase (EC 6.3.1.2), and glutamate synthase (EC 2.6.1.53) was examined for cultures of Salmonella typhimurium grown with various nitrogen and amino acid sources. In contrast to the regulatory pattern observed in Klebsiella aerogenes, the glutamate dehydrogenase levels of S. typhimurium do not decrease when glutamine synthetase is derepressed during growth with limiting ammonia. Thus, it appears that the S. typhimurium glutamine synthetase does not regulate the synthesis of glutamate dehydrogenase as reported for K. aerogenes. The glutamate dehydrogenase activity does increase, however, during growth of a glutamate auxotroph with glutamate as a limiting amino acid source. The regulation of glutamate synthase levels is complex with the enzyme activity decreasing during growth with glutamate as a nitrogen source, and during growth of auxotrophs with either glutamine or glutamate as limiting amino acids.
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PMID:Regulation of the ammonia assimilatory enzymes in Salmonella typhimurium. 24 Aug 4

Klebsiella aerogenes utilized arginine as the sole source of carbon or nitrogen for growth. Arginine was degraded to 2-ketoglutarate and not to succinate, since a citrate synthaseless mutant grows on arginine as the only nitrogen source. When glucose was the energy source, all four nitrogen atoms of arginine were utilized. Three of them apparently did not pass through ammonia but were transferred by transamination, since a mutant unable to produce glutamate by glutamate synthase or glutamate dehydrogenase utilized three of four nitrogen atoms of arginine. Urea was not involved as intermediate, since a unreaseless mutant did not accumulate urea and grew on arginine as efficiently as the wild-type strain. Ornithine appeared to be an intermediate, because cells grown either on glucose and arginine or arginine alone could convert arginine in the presence of hydroxylamine to ornithine. This indicates that an amidinotransferase is the initiating enzyme of arginine breakdown. In addition, the cells contained a transaminase specific for ornithine. In contrast to the hydroxylamine-dependent reaction, this activity could be demonstrated in extracts. The arginine-utilizing system (aut) is apparently controlled like the enzymes responsible for the degradation of histidine (hut) through induction, catabolite repression, and activation by glutamine synthetase.
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PMID:Utilization of arginine by Klebsiella aerogenes. 34 1


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