The Use of Mutants Lacking Glutamine Synthetase and Glutamate Synthase to Study their Role in Plant Nitrogen Metabolism

1989 ◽  
pp. 157-189 ◽  
Author(s):  
Peter J. Lea ◽  
Ray D. Blackwell ◽  
Alan J. S. Murray ◽  
Knenneth W. Joy
Keyword(s):  
Glutamine Synthetase ◽  
Nitrogen Metabolism ◽  
Glutamate Synthase ◽  
Plant Nitrogen

scholarly journals Localization, Gene Expression, and Functions of Glutamine Synthetase Isozymes in Wheat Grain (Triticum aestivum L.)

2021 ◽  
Vol 12 ◽  
Author(s):  
Yihao Wei ◽  
Shuping Xiong ◽  
Zhiyong Zhang ◽  
Xiaodan Meng ◽  
Lulu Wang ◽  
...  
Keyword(s):  
Glutamine Synthetase ◽  
Nitrogen Metabolism ◽  
Glutamate Synthase ◽  
Grain Filling ◽  
Maximum Activity ◽  
Transfer Cells ◽  
Aleurone Layer ◽  
Wheat Grain ◽  
Plant Nitrogen ◽  
Endosperm Transfer Cells

Glutamine synthetase (GS) plays a major role in plant nitrogen metabolism, but the roles of individual GS isoforms in grains are unknown. Here, the localization and expression of individual TaGS isozymes in wheat grain were probed with TaGS isoenzyme-specific antibodies, and the nitrogen metabolism of grain during the grain filling stage were investigated. Immunofluorescence revealed that TaGS1;1, TaGS1;3, and TaGS2 were expressed in different regions of the embryo. In grain transporting tissues, TaGS1;2 was localized in vascular bundle; TaGS1;2 and TaGS1;1 were in chalaza and placentochalaza; TaGS1;1 and TaGS1;3 were in endosperm transfer cells; and TaGS1;3 and TaGS2 were in aleurone layer. GS exhibited maximum activity and expression at 8 days after flowering (DAF) with peak glutamine content in grains; from then, NH4+ increased largely from NO3- reduction, glutamate dehydrogenase (GDH) aminating activity increased continuously, and the activities of GS and glutamate synthase (GOGAT) decreased, while only TaGS1;3 kept a stable expression in different TaGS isozymes. Hence, GS-GOGAT cycle and GDH play different roles in NH4+ assimilation of grain in different stages of grain development; TaGS1;3, located in aleurone layer and endosperm transfer cells, plays a key role in Gln into endosperm for gluten synthesis. At 30 DAF, grain amino acids are mainly transported from maternal phloem.

Enzymes of Nitrogen Metabolism in Legume Nodules: a Comparative Study

1978 ◽  
Vol 5 (5) ◽  
pp. 553 ◽  
Author(s):  
MJ Boland ◽  
HM Fordyce ◽  
RM Greenwood
Keyword(s):  
Glutamine Synthetase ◽  
Comparative Study ◽  
Glutamate Dehydrogenase ◽  
Nitrogen Metabolism ◽  
Glutamate Synthase ◽  
Ammonia Assimilation ◽  
Legume Species

Levels of activity of glutamine synthetase, glutamate dehydrogenase and NADH-dependent glutamate synthase in nodule cytoplasm extracts of twelve herbaceous legume species have been measured. Nodules of all species contained substantial quantities of glutamine synthetase. Levels of glutamate synthase were found to be between 7 and 100% of those of glutamine synthetase, while levels of glutamate dehydrogenase varied widely between 0.2 and 150% of those of glutamine synthetase. The estimated Km for hydroxylamine of glutamine synthetase was found to vary between 0.02 and 0.5 mM in nine species tested, while that of glutamate dehydrogenase for ammonia varied between 0.03 M and 0.1 M in the four species containing significant levels of that enzyme. It is proposed that the pathway of ammonia assimilation via glutamine synthetase and NADH-dependent glutamate synthase-catalysed reactions is universal in legume nodule metabolism.

scholarly journals Phytohormone up-regulates the biochemical constituent, exopolysaccharide and nitrogen metabolism in paddy-field cyanobacteria exposed to chromium stress

2020 ◽  
Author(s):  
Sanjesh Tiwari ◽  
Anuradha Patel ◽  
Sheo Mohan Prasad
Keyword(s):  
Nitrogen Metabolism ◽  
Uptake Rate ◽  
Paddy Field ◽  
Growth Parameter ◽  
Glutamate Synthase ◽  
Nostoc Muscorum ◽  
Biochemical Constituent ◽  
Diazotrophic Cyanobacteria ◽  
Chromium Stress ◽  
Cr Uptake

Abstract Current study deals with the assuaging effects of two phytohormones; indole acetic acid (IAA; 290 nM) and kinetin (KN; 10 nM) on growth, phycobiliproteins, status of nitrogen metabolism and biochemical constituents; protein, carbohydrate and exopolysaccharide contents in two diazotrophic cyanobacteria Nostoc muscorum and Anabaena exposed to chromium (CrVI) stress (100 µM and 150 µM). Chromium individually at both the tested doses expressively declined the growth, chlorophyll a to carotenoid ratio and contents of phycobiliproteins; phycocyanin (PC), allophycocyanin (APC), and phycoerythrin (PE). With distinctive impact on status of nitrogen metabolism chromium significantly reduced the nitrate (NO3—) and nitrite (NO2—) uptake rate and foremost decrease in nitrate and ammonia assimilating enzyme; nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthase (GOGAT) except glutamate dehydrogenase (GDH). However, beneath alike condition, exogenous application of IAA and KN exhibited noteworthy assuaging effects on growth-regulating parameters in both the paddy field cyanobacteria, which consummately occurred as a result of substantial decrease in Cr uptake and inducing signaling responses and also enhances the growth parameter i.e. nitrogen metabolism as a result of considerable lowering in Cr induced damaging effect on nitrogen metabolism and uptake rate, and the alleviating effect was more pronounced with the lower dose of Cr, efficient in N.muscorum than Anabaena.

Regulation of Glutamine Synthetase/Glutamate Synthase Cycle in Maize Tissues, Effect of the Nitrogen Source

1986 ◽  
Vol 124 (1-2) ◽  
pp. 147-154 ◽  
Author(s):  
Víctor M. Loyola-Vargas ◽  
Estela Sánchez de Jiménez
Keyword(s):  
Glutamine Synthetase ◽  
Nitrogen Source ◽  
Glutamate Synthase

Ammonia, glutamine, and asparagine: a carbon–nitrogen interface

1988 ◽  
Vol 66 (10) ◽  
pp. 2103-2109 ◽  
Author(s):  
K. W. Joy
Keyword(s):  
Glutamine Synthetase ◽  
Glutamate Dehydrogenase ◽  
Higher Plants ◽  
Amino Nitrogen ◽  
Glutamate Synthase ◽  
Dinitrogen Fixation ◽  
Similar Function ◽  
Metabolic Processes ◽  
Organic Form ◽  
Primary Input

In plants, the primary input of nitrogen (obtained from the soil or from symbiotic dinitrogen fixation) occurs through the assimilation of ammonia into organic form. Synthesis of glutamine (via glutamine synthetase) is the major, and possibly exclusive, route for this process, and there is little evidence for the participation of glutamate dehydrogenase. A variety of reactions distribute glutamine nitrogen to other compounds, including transfer to amino nitrogen through glutamate synthase. In many plants asparagine is a major recipient of glutamine nitrogen and provides a mobile reservoir for transport to sites of growth; ureides perform a similar function in some legumes. Utilisation of transport forms of nitrogen, and a number of other metabolic processes, involves release of ammonia, which must be reassimilated. In illuminated leaves, there is an extensive flux of ammonia released by the photorespiratory cycle, requiring continuous efficient reassimilation. Aspects of ammonia recycling and related amide metabolism in higher plants are reviewed.

Glutamate synthase levels in Neurospora crassa mutants altered with respect to nitrogen metabolism

1981 ◽  
Vol 1 (2) ◽  
pp. 158-164
Author(s):  
N S Dunn-Coleman ◽  
E A Robey ◽  
A B Tomsett ◽  
R H Garrett
Keyword(s):  
Neurospora Crassa ◽  
Glutamate Dehydrogenase ◽  
Nitrogen Metabolism ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Glutamate Synthase ◽  
Wild Type ◽  
Mutant Strains ◽  
Synthase Regulation ◽  
Glutamate Biosynthesis ◽  
Glutamine Limitation

Glutamate synthase catalyzes glutamate formation from 2-oxoglutarate plus glutamine and plays an essential role when glutamate biosynthesis by glutamate dehydrogenase is not possible. Glutamate synthase activity has been determined in a number of Neurospora crassa mutant strains with various defects in nitrogen metabolism. Of particular interest were two mutants phenotypically mute except in an am (biosynthetic nicotinamide adenine dinucleotide phosphate-glutamate dehydrogenase deficient, glutamate requiring) background. These mutants, i and en-am, are so-called enhancers of am; they have been redesignated herein as en(am)-1 and en(am)-2, respectively. Although glutamate synthase levels in en(am)-1 were essentially wild type, the en(am)-2 strain was devoid of glutamate synthase activity under all conditions examined, suggesting that en(am)-2 may be the structural locus for glutamate synthase. Regulation of glutamate synthase occurred to some extent, presumably in response to glutamate requirements. Glutamate starvation, as in am mutants, led to enhanced activity. In contrast, glutamine limitation, as in gln-1 mutants, depressed glutamate synthase levels.

scholarly journals Metagenomic Insights into the Effects of Seasonal Temperature Variation on the Activities of Activated Sludge

2019 ◽  
Vol 7 (12) ◽  
pp. 713 ◽  
Author(s):  
Chenbing Ai ◽  
Zhang Yan ◽  
Han Zhou ◽  
Shanshan Hou ◽  
Liyuan Chai ◽  
...  
Keyword(s):  
Microbial Community ◽  
Glutamine Synthetase ◽  
Activated Sludge ◽  
Temperature Variation ◽  
Nitrogen Metabolism ◽  
Metagenomic Data ◽  
Seasonal Temperature ◽  
Simulated Temperature ◽  
Genes Encoding ◽  
Seasonal Temperature Variation

It is well acknowledged that the activities of activated sludge (AS) are influenced by seasonal temperature variation. However, the underlying mechanisms remain largely unknown. Here, the activities of activated sludge under three simulated temperature variation trends were compared in lab-scale. The TN, HN3-H, and COD removal activities of activated sludge were improved as temperature elevated from 20 °C to 35 °C. While, the TN, HN3-H, COD and total phosphorus removal activities of activated sludge were inhibited as temperature declined from 20 °C to 5 °C. Both the extracellular polymer substances (EPS) composition (e.g., total amount, PS, PN and DNA) and sludge index of activated sludge were altered by simulated seasonal temperature variation. The variation of microbial community structures and the functional potentials of activated sludge were further explored by metagenomics. Proteobacteria, Actinobacteria, Acidobacteria and Bacteroidetes were the dominant phyla for each activated sludge sample under different temperatures. However, the predominant genera of activated sludge were significantly modulated by simulated temperature variation. The functional genes encoding enzymes for nitrogen metabolism in microorganisms were analyzed. The enzyme genes related to ammonification had the highest abundance despite the changing temperature, especially for gene encoding glutamine synthetase. With the temperature raising from 20 °C to 35 °C. The abundance of amoCAB genes encoding ammonia monooxygenase (EC:1.14.99.39) increased by 305.8%. Meanwhile, all the enzyme genes associate with denitrification were reduced. As the temperature declined from 20 °C to 5 °C, the abundance of enzyme genes related to nitrogen metabolism were raised except for carbamate kinase (EC:2.7.2.2), glutamate dehydrogenase (EC:1.4.1.3), glutamine synthetase (EC:6.3.1.2). Metagenomic data indicate that succession of the dominant genera in microbial community structure is, to some extent, beneficial to maintain the functional stability of activated sludge under the temperature variation within a certain temperature range. This study provides novel insights into the effects of seasonal temperature variation on the activities of activated sludge.

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