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.

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.

Effect of pyruvate on the metabolic regulation of nitrogenase activity in Rhodospirillum rubrum in darkness

Microbiology ◽  
2011 ◽  
Vol 157 (6) ◽  
pp. 1834-1840 ◽  
Author(s):  
Tiago Toscano Selao ◽  
Tomas Edgren ◽  
He Wang ◽  
Agneta Norén ◽  
Stefan Nordlund
Keyword(s):  
Nitrogen Source ◽  
Metabolic Regulation ◽  
Rhodospirillum Rubrum ◽  
De Novo ◽  
Nitrogenase Activity ◽  
Signal Transduction Pathway ◽  
Nitrogen Sources ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Fe Protein

Rhodospirillum rubrum, a photosynthetic diazotroph, is able to regulate nitrogenase activity in response to environmental factors such as ammonium ions or darkness, the so-called switch-off effect. This is due to reversible modification of the Fe-protein, one of the two components of nitrogenase. The signal transduction pathway(s) in this regulatory mechanism is not fully understood, especially not in response to darkness. We have previously shown that the switch-off response and metabolic state differ between cells grown with dinitrogen or glutamate as the nitrogen source, although both represent poor nitrogen sources. In this study we show that pyruvate affects the response to darkness in cultures grown with glutamate as nitrogen source, leading to a response similar to that in cultures grown with dinitrogen. The effects are related to PII protein uridylylation and glutamine synthetase activity. We also show that pyruvate induces de novo protein synthesis and that inhibition of pyruvate formate-lyase leads to loss of nitrogenase activity in the dark.

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 Reduced Glutamine Synthetase Activity Alters the Fecundity of Female Bactrocera dorsalis (Hendel)

Insects ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 186 ◽  
Author(s):  
Dong Wei ◽  
Meng-Yi Zhang ◽  
Ying-Xin Zhang ◽  
Su-Yun Zhang ◽  
Guy Smagghe ◽  
...  
Keyword(s):  
Gene Expression ◽  
Enzyme Activity ◽  
Glutamine Synthetase ◽  
Egg Production ◽  
Fat Body ◽  
Specific Inhibitor ◽  
Bactrocera Dorsalis ◽  
Transcriptional Level ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity

Glutamine synthetase (GS) is a key enzyme in glutamine synthesis and is associated with multiple physiological processes in insects, such as embryonic development, heat shock response, and fecundity regulation. However, little is known about the influence of GS on female fecundity in the oriental fruit fly, Bactrocera dorsalis. Based on the cloning of BdGSs, mitochondrial BdGSm and cytoplasmic BdGSc, we determined their expressions in the tissues of adult B. dorsalis. BdGSm was highly expressed in the fat body, while BdGSc was highly expressed in the head and midgut. Gene silencing by RNA interference against two BdGSs isoforms suppressed target gene expression at the transcriptional level, leading to a reduced ovarian size and lower egg production. The specific inhibitor L-methionine S-sulfoximine suppressed enzyme activity, but only the gene expression of BdGSm was suppressed. A similar phenotype of delayed ovarian development occurred in the inhibitor bioassay. Significantly lower expression of vitellogenin and vitellogenin receptor was observed when GS enzyme activity was suppressed. These data illustrate the effects of two GS genes on adult fecundity by regulating vitellogenin synthesis in different ways.

scholarly journals THE INFLUENCE OF BACTERIA OF GENUS AZOSPIRILLUM ON POTENTIAL NITROGENASE ACTIVITY AND BIOSYNTETIC PROCESSES OF SPRING WHEAT AND SPRING TRITICALE

2009 ◽  
Vol 9 ◽  
pp. 138-146
Author(s):  
O.O. Shahovnina ◽  
O.V. Nadkernichna ◽  
Y.O. Vorobey ◽  
V.V. Krivopisha
Keyword(s):  
Glutamine Synthetase ◽  
Spring Wheat ◽  
Root Zone ◽  
Nitrogenase Activity ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Nitrogen Fixing ◽  
Nitrogen Fixing Bacteria ◽  
Spring Triticale ◽  
Reliable Increase

Use of new strain of nitrogen fixing bacteria Azospirillum sp. 77 for inoculation of spring wheat and spring triticale permitted to form an effective associative system diasotroph - plant. The bacterization promoted the reliable increase of potential nitrogenase activity in root zone of plant by 38-220 %, activated the biosynthetic processes, in particular, glutamine synthetase activity increased by 57,0-71,9 %, content of protein in leaves - by 9,7-16,3 %, top of the plants - by 11,9- 18,9 %, weight of the roots - by 7,2-7,3 %.

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