Nitrogen source affects glutamine synthetase activity in Pantoea sp.; bacterium inoculation promotes rice seedlings’ growth

2011 ◽  
Vol 5 (27) ◽  
Author(s):  
Iriam Salazar-Gutiérrez
Keyword(s):  
Glutamine Synthetase ◽  
Nitrogen Source ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Rice Seedlings

Glutamine synthetase from Mycobacterium avium

1984 ◽  
Vol 30 (3) ◽  
pp. 353-359 ◽  
Author(s):  
Maria E. Alvarez ◽  
C. M. McCarthy
Keyword(s):  
Enzyme Activity ◽  
Glutamine Synthetase ◽  
Nitrogen Source ◽  
Mycobacterium Avium ◽  
Specific Activity ◽  
Sedimentation Coefficient ◽  
Ammonia Assimilation ◽  
Methionine Sulfoximine ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity

Mycobacterium avium was previously shown to be dependent upon ammonia or glutamine as a nitrogen source. In an effort to assess the physiology of ammonia assimilation by M. avium, a characterization of its glutamine synthetase was performed. The enzyme from M. avium was purified by streptomycin sulfate treatment, ammonium sulfate precipitation, and affinity chromatography. The enzyme was unusual in that it had a pH optimum of 6.4 and maximum enzyme activity was obtained between 50 and 60 °C as shown by the transferase assay. The glutamine synthetase activity from batch-cultured cells decreased with increasing concentration of ammonium chloride in the range of 0.25–5 μ mol/mL of medium, which demonstrated a response to environmental supply of a nitrogen source. The mycobacterial enzyme was similar to the other bacterial glutamine synthetases in terms of molecular weight and sedimentation coefficient which were 600 000 and 19.5 S, respectively, and enzyme activity was lost by treatment with a glutamate analog, methionine sulfoximine. The isoelectric point was, however, pH 4.5. Treatment of the enzyme with snake venom phosphodiesterase resulted in an increase in specific activity. AMP was released by the phosphodiesterase treatment, thus demonstrating that M. avium glutamine synthetase was regulated by adenylylation modification.

scholarly journals Nitrogenase Switch-Off and Regulation of Ammonium Assimilation in Response to Light Deprivation in Rhodospirillum rubrum Are Influenced by the Nitrogen Source Used during Growth

2009 ◽  
Vol 192 (5) ◽  
pp. 1463-1466 ◽  
Author(s):  
Pedro Filipe Teixeira ◽  
He Wang ◽  
Stefan Nordlund
Keyword(s):  
Nitrogen Fixation ◽  
Glutamine Synthetase ◽  
Nitrogen Source ◽  
Rhodospirillum Rubrum ◽  
Light Availability ◽  
Ammonium Assimilation ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Light Deprivation

ABSTRACT Nitrogen fixation and ammonium assimilation in Rhodospirillum rubrum are regulated in response to changes in light availability, and we show that the response in terms of glutamine synthetase activity and PII modification is dependent on the nitrogen source used for growth, N2 or glutamate, although both lead to nitrogenase derepression.

scholarly journals GlnD Is Essential for NifA Activation, NtrB/NtrC-Regulated Gene Expression, and Posttranslational Regulation of Nitrogenase Activity in the Photosynthetic, Nitrogen-Fixing Bacterium Rhodospirillum rubrum

2005 ◽  
Vol 187 (4) ◽  
pp. 1254-1265 ◽  
Author(s):  
Yaoping Zhang ◽  
Edward L. Pohlmann ◽  
Gary P. Roberts
Keyword(s):  
Gene Expression ◽  
Glutamine Synthetase ◽  
Nitrogen Source ◽  
Rhodospirillum Rubrum ◽  
Synthetase Activity ◽  
Posttranslational Regulation ◽  
Glutamine Synthetase Activity ◽  
Sole Nitrogen Source ◽  
Nitrogen Fixing ◽  
Regulated Gene Expression

ABSTRACT GlnD is a bifunctional uridylyltransferase/uridylyl-removing enzyme and is thought to be the primary sensor of nitrogen status in the cell. It plays an important role in nitrogen assimilation and metabolism by reversibly regulating the modification of PII proteins, which in turn regulate a variety of other proteins. We report here the characterization of glnD mutants from the photosynthetic, nitrogen-fixing bacterium Rhodospirillum rubrum and the analysis of the roles of GlnD in the regulation of nitrogen fixation. Unlike glnD mutations in Azotobacter vinelandii and some other bacteria, glnD deletion mutations are not lethal in R. rubrum. Such mutants grew well in minimal medium with glutamate as the sole nitrogen source, although they grew slowly with ammonium as the sole nitrogen source (MN medium) and were unable to fix N2. The slow growth in MN medium is apparently due to low glutamine synthetase activity, because a ΔglnD strain with an altered glutamine synthetase that cannot be adenylylated can grow well in MN medium. Various mutation and complementation studies were used to show that the critical uridylyltransferase activity of GlnD is localized to the N-terminal region. Mutants with intermediate levels of uridylyltransferase activity are differentially defective in nif gene expression, the posttranslational regulation of nitrogenase, and NtrB/NtrC function, indicating the complexity of the physiological role of GlnD. These results have implications for the interpretation of results obtained with GlnD in many other organisms.

Respective effects of glucose and glutamine on the glutamine synthetase activity of human skin fibroblasts

1991 ◽  
Vol 102 (2) ◽  
Author(s):  
Th�ophile Soni ◽  
Claire Wolfrom ◽  
Samia Guerroui ◽  
Nicole Raynaud ◽  
Jos�phine Poggi ◽  
...  
Keyword(s):  
Glutamine Synthetase ◽  
Human Skin ◽  
Skin Fibroblasts ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Human Skin Fibroblasts
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