Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Regulation of the expression of the histidase coded by hutk of Klebsiella aerogenes in Salmonella typhimurium and in Escherichia coli and of the expression of the histidase coded by huts of S. typhimurium in E. coli was investigated. The hutk histidase was found to be sensitive to catabolite repression in K. aerogenes and in E. coli, but insensitive to catabolite repression in S. typhimurium; huts histidase has previously been shown to be catabolite sensitive in all three organisms. The expression of both hutk and huts histidase in E. coli was activated by nitrogen starvation. Apparently, the glutamine synthetase of E. coli may activate the formation of some glutamate- and ammonia-producing enzymes.
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PMID:Regulation of histidase synthesis in intergeneric hybrids of enteric bacteria. 0 26

Synthesis of glutamine synthetase (GS) in anaerobic batch cultures of Escherichia coli was repressed when excess NH4+ was available, but derepressed during growth with a poor nitrogen source. In wild-type bacteria there was only a weak inverse correlation between the activities of GS and glutamate dehydrogenase (GDH) during growth in various media. No positive correlations were found between the activities of GS and nitrite reductase, or between GS and cytochrome c552: both of these proteins were synthesized normally by mutants that contained no active GS. Although activities of GS and GDH were low in two mutants that are unable to synthesize cytochrome c552 or reduce nitrite because of defects in the nirA gene, the nirA defect was separated from the GS and GDH defects by transduction with bacteriophage P1. Attempts to show that catabolite repression of proline oxidase synthesis could be relieved during NH4+ starvation also failed. It is, therefore, unlikely that nitrite reduction or proline oxidation by E. coli are under positive control by GS protein. The regulation of the synthesis of enzymes for the utilization of secondary nitrogen sources in E. coli, therefore, different from that in Klebsiella aerogenes, but is similar to that in Salmonella typhimurium.
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PMID:Lack of a regulatory function for glutamine synthetase protein in the synthesis of glutamate dehydrogenase and nitrite reductase in Escherichia coli K12. 1 79

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

Azaguanine-resistant mutants of Chinese hamster ovary cells were isolated following mutagenesis with ICR-17OG. Of the eight mutant isolates examined, only one, Ag-5 had detectable hypoxanthine(guanine)phosphoribosyltransferase activity. Under normal conditions of growth, de novo purine biosynthesis in the mutants was not significantly different from wild type. However, when the cultures were starved for glutamine over a 2 h period before measuring 5'phosphoribosyl formylglycinamide (a relative measure of de novo purine biosynthesis), elevated levels of 5'-phosphoribosyl formylglycinamide accumulated in some of the mutants, and decreased levels in wild type and Ag-5. The level of purine biosynthesis could be related to the levels of glutamine in the pregrowth medium. The rate of purine biosynthesis correlated with 5-phosphoribosyl pyrophosphate levels, which were enhanced in the mutant (Ag-C) following the starvation period. No alterations were found in levels of 5-phosphoribosyl pyrophosphate synthetase or glutamine synthetase. The extent of feedback inhibition was normal in both mutant and wild type cells. These data suggest that the hypoxanthine (guanine) phosphoribosyltransferase locus is a regulatory gene.
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PMID:Regulation of de novo purine biosynthesis in normal and 8-azaguanine-resistant Chinese hamster cells. 20 17

The GLN1 gene, encoding glutamine synthetase in Saccharomyces cerevisiae, was sequenced, and its encoded polypeptide was shown to have significant homology to other eukaryotic glutamine synthetases. S1 analysis has defined the transcriptional start site of the gene. Upstream analysis of the gene using lacZ fusions has verified transcriptional control of the gene and has identified a nitrogen upstream activation sequence which is required for the increased transcription of GLN1 seen when glutamine is replaced by glutamate as the nitrogen source. cis-acting sites required for the increased transcription in response to purine starvation also have been localized.
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PMID:Sequence of the GLN1 gene of Saccharomyces cerevisiae: role of the upstream region in regulation of glutamine synthetase expression. 134 68

Glutamine synthetase activity from Synechocystis sp. strain PCC 6803 is regulated as a function of the nitrogen source available in the medium. Addition of 0.25 mM NH4Cl to nitrate-grown cells promotes a clear short-term inactivation of glutamine synthetase, whose enzyme activity decreases to 5 to 10% of the initial value in 25 min. The intracellular levels of glutamine, determined under various conditions, taken together with the results obtained with azaserine (an inhibitor of transamidases), rule out the possibility that glutamine per se is responsible for glutamine synthetase inactivation. Nitrogen starvation attenuates the ammonium-mediated glutamine synthetase inactivation, indicating that glutamine synthetase regulation is modulated through the internal balance between carbon-nitrogen compounds and carbon compounds. The parallelism observed between the glutamine synthetase activity and the internal concentration of alpha-ketoglutarate suggests that this metabolite could play a role as a positive effector of glutamine synthetase activity in Synechocystis sp. Despite the similarities of this physiological system to that described for enterobacteria, the lack of in vivo 32P labeling of glutamine synthetase during the inactivation process excludes the existence of an adenylylation-deadenylylation system in this cyanobacterium.
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PMID:Regulation of glutamine synthetase activity in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 by the nitrogen source: effect of ammonium. 167 97

Cytoplasmic and mitochondrial molecular forms of glutamine synthetase (CE 6.3.1.2) have been isolated from the carp muscle with purification degree of 100 and 165 times and output 9.0%. It is established that the temperature optimum of the cytoplasmic form activity is 30 degrees C and that of mitochondrial one--20 degrees C; the pH optimum for the both molecular forms is 6.0 and 8.2. The optimal ratio [Me2+] : [ATP] for the isolated form is 2:1; Km (seeming) of the cytoplasmic form in the presence of Mg2+ is 6.0 mM for glutamate, 0.035 for ammonium, for ATP 0.5 and 0.7 for magnesium ions; these values for the mitochondrial form are: 14.3, 0.048, 1.0 and 0.8 mM, respectively. Activity of the both glutamine synthetases with Mg2+ ions is almost by 50% higher than that of glutamine synthetases with Mn2+ ions. Seasonal regularities of the synthesis of molecular glutamine synthetase forms have been established in vivo. Cytoplasmic form is present in the muscles all year round, while mitochondrial one only in winter at low temperature of the environment and fish starvation. Differences in properties and seasonal character of synthesis of molecular glutamine synthetase forms in carp muscles are a result of diversity of their functional role.
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PMID:[Multiple molecular forms of glutamine synthetase in carp muscles]. 167 61

A hybridocytochemical analysis of adult liver from normal control and from hormonally and dietary-treated rats was carried out, using radioactively-labelled probes for the mRNAs of glutamine synthetase (GS), carbamoylphosphate synthetase (CPS) and phosphoenolpyruvate carboxykinase (PEPCK). In line with previous findings, GS mRNA is exclusively expressed in a small pericentral compartment, CPS mRNA exclusively in a contiguous large periportal compartment and PEPCK mRNA across the entire porto-central distance. The density of labelling in CPS and PEPCK mRNA-positive hepatocytes decreases in a porto-central direction. Starvation resulted in a reversal of the gradient of CPS mRNA within its periportal compartment; glucose refeeding counteracted this effect. Livers of glucocorticosteroid-treated, starved or diabetic rats also revealed a reversal of the normal gradient of CPS mRNA, but now across the entire porto-central distance. The patterns of expression of GS and PEPCK mRNA remained essentially unchanged, notwithstanding substantial changes in the levels of expression. It is concluded that blood-borne factors constitute the major determinants for the expression patterns of CPS mRNA within the context of the architecture of the liver lobulus.
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PMID:Diet- and hormone-induced reversal of the carbamoylphosphate synthetase mRNA gradient in the rat liver lobulus. 197 48

It has been found that there exists a correlation in the dynamics of changes in the amount of glutamate, alpha-ketoglutarate, glutamine, ammonia and activity level or alpha-ketoglutarate dehydrogenase, NADP-glutamate dehydrogenase, glutamine synthetase and glutaminase in the brain of young carp in the process of winter starvation. It has been stated that under condition of energy deficiency and meaningful amount of ammonia in the organism of hibernating fish, its binding parallel with the known glutamine synthetase mechanism may proceed in the course of the NADP-glutamate dehydrogenase reaction which balance is shifted towards the glutamate synthesis. This reaction is supposed to provide the outflow of alpha-ketoglutarate from the citric cycle, which intensifies energy deficiency of the organism.
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PMID:[Features of the interconversion of alpha-ketoglutarate--glutamate in brain mitochondria of exothermic animals during hibernation]. 198 77

In this paper we have examined whether the four glutamine synthetase (gln) genes, expressed in roots and nodules of Phaseolus vulgaris are substrate-inducible by ammonium. Manipulation of the ammonium pool in roots, through addition and removal of exogenous ammonium, did not elicit any changes in the abundances of the four mRNAs thus suggesting that the gln genes in roots of this legume are neither substrate-inducible by ammonium nor derepressed during nitrogen starvation. In nodules the effect of the ammonium supply on expression of the gln genes has been examined by growing nodules under argon/oxygen atmospheres, or with a number of Fix- Rhizobium mutants, and following addition of exogenous ammonium. The results of these experiments suggest that the expression of the gln-gamma gene, which is strongly induced during nodule development, is primarily under a developmental control. However nitrogen fixation appears to have a quantitative effect on expression of gln-gamma as the abundance of this mRNA is about 2 to 4-fold higher under nitrogen-fixing conditions. This effect could not be mimicked by addition of exogenous ammonium and moreover is not specific to the gln-gamma gene as mRNA from a leghaemoglobin gene was similarly affected. Taken together these results have failed to find an effect of ammonium on specifically inducing the expression of glutamine synthetase genes in roots and nodules of P. vulgaris.
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PMID:Expression of glutamine synthetase genes in roots and nodules of Phaseolus vulgaris following changes in the ammonium supply and infection with various Rhizobium mutants. 198 88


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