A light-dependent redox signal participates in the regulation of ammonia fixation in chloroplasts of higher plants — ferredoxin: Glutamate synthase is a thioredoxin-dependent enzyme

1998 ◽  
Vol 153 (1-2) ◽  
pp. 83-90 ◽  
Author(s):  
A. Lichter ◽  
I. Häberlein
Keyword(s):  
Higher Plants ◽  
Glutamate Synthase ◽  
Ammonia Fixation

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.

Corrigendum to: Ammonium metabolism in Selaginella bryopteris in response to dehydration-rehydration and characterisation of desiccation tolerant, thermostable, cytosolic glutamine synthetase from plant

2021 ◽  
Vol 48 (3) ◽  
pp. 358
Author(s):  
Kamal K. Singh ◽  
Shyamaprasad Saha ◽  
Ram C. Kadiravana ◽  
Deepika Mazumdar ◽  
Vijeta Rai ◽  
...  
Keyword(s):  
Glutamine Synthetase ◽  
Metabolic Regulation ◽  
Specific Activity ◽  
Higher Plants ◽  
Glutamate Synthase ◽  
Immunoblot Analysis ◽  
Primary Metabolism ◽  
Ammonium Metabolism ◽  
Free Ammonium ◽  
Selaginella Bryopteris

Water deficit (WD) has adverse effects on plant growth, and acclimation requires responses allowing primary metabolism to continue. Resurrection plants can serve as model system to gain insight into metabolic regulation during WD. We herein report the response of a resurrection lycophyte, Selaginella bryopteris, to dehydration-rehydration cycle with emphasis on ammonium metabolism. Dehydration of S. bryopteris fronds resulted in decrease of total protein and increase of free ammonium levels and the effect was reversed on rehydration. The proline content increased twice after 24 h of dehydration, which again recovered to background levels comparable to that at full turgor state. The specific activity of glutamine synthetase (GS) didn’t change significantly till 6 h and then declined by 21% after 24 h of dehydration, whereas specific activities of glutamate synthase (GOGAT) and aminating glutamate dehydrogenase (GDH) were enhanced significantly during dehydration. The deaminating activity of GDH also increased during dehydration albeit at a slower rate. Immunoblot analysis indicated overexpression of GS and GDH polypeptides during dehydration and their levels declined on rehydration. The results suggested significant role of GDH along with GS/GOGAT in production of nitrogen-rich amino acids for desiccation tolerance. Unlike higher plants S. bryopteris expressed GS only in cytosol. The enzyme had pH and temperature optima of 5.5 and 60°C, respectively, and it retained 96% activity on preincubation at 60°C for 30 min indicating thermostability. Hence, like higher plants the cytosolic GS from S. bryopteris has a conserved role in stress tolerance.

scholarly journals Ammonia Fixation via Glutamine Synthetase and Glutamate Synthase in the CAM Plant Cissus quadrangularis L.

1986 ◽  
Vol 81 (2) ◽  
pp. 356-360 ◽  
Author(s):  
Michael G. Berger ◽  
Michael L. Sprengart ◽  
Misri Kusnan ◽  
Heinrich P. Fock
Keyword(s):  
Glutamine Synthetase ◽  
Glutamate Synthase ◽  
Cissus Quadrangularis ◽  
Cam Plant ◽  
Ammonia Fixation

A survey of the presence of glutamate synthase in plant cell suspension cultures

1976 ◽  
Vol 54 (24) ◽  
pp. 2924-2927 ◽  
Author(s):  
Donald K. Dougall ◽  
Jeff Bloch
Keyword(s):  
Cell Suspension ◽  
Higher Plants ◽  
Cell Suspension Cultures ◽  
Glutamate Synthase ◽  
Pyridine Nucleotide ◽  
Suspension Cultures ◽  
Higher Plant ◽  
Plant Cell Suspension Cultures ◽  
Plant Cell Suspension ◽  
Glutamic Dehydrogenase

Evidence was sought for the presence of glutamate synthase (EC 2.6.1.53) in extracts from suspension cultures of six higher plant species not previously examined. The level of glutamate synthase measured was above the level of glutamic dehydrogenase (EC 1.4.1.2, 1.4.1.4) in extracts of soybean, parsley, okra, and cotton. Glutamate synthase was detectable but less than glutamic dehydrogenase in extracts of sugarcane. Glutamate synthase was not detected in extracts of peanut. Evidence for two glutamate synthases, each specific for one pyridine nucleotide, was obtained with cultures of carrot. Glutamate synthase has now been detected in eight and possibly nine species representing four and possibly five families of higher plants.

Studies on Glutamate Synthase from the Leaves of Higher Plants

1977 ◽  
Vol 28 (3) ◽  
pp. 588-596 ◽  
Author(s):  
R. M. WALLSGROVE ◽  
E. HAREL ◽  
P. J. LEA ◽  
B. J. MIFLIN
Keyword(s):  
Higher Plants ◽  
Glutamate Synthase

Correlation Between the Development of Photorespiration and the Change in Activities of NH3 Assimilation Enzymes in Greening Oat Leaves

1991 ◽  
Vol 18 (6) ◽  
pp. 583 ◽  
Author(s):  
JW Yu ◽  
KC Woo
Keyword(s):  
Avena Sativa ◽  
Co2 Fixation ◽  
Chloroplast Development ◽  
Photosynthetic Capacity ◽  
Higher Plants ◽  
Glutamate Synthase ◽  
Chlorophyll Synthesis ◽  
Continuous Illumination ◽  
Bisphosphate Carboxylase ◽  
Glutamate Dehydrogenase Activity

The development of photosynthetic capacity and photorespiration during chloroplast development in 7-day-old etiolated oat (Avena sativa L.) primary leaves was investigated together with changes in the activity of possible NH3-assimilating enzymes. The development of photosynthetic CO2 fixation and photorespiration capacity, and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and glutamine synthetase (GS) activities comparable to green leaves were completed within 48 h of continuous illumination. Chlorophyll synthesis and glutamate synthase (GOGAT) activity continued to increase beyond this time. Within this 48-h period, the activities of Rubisco, GS and GOGAT increased 2.3, 2 and 3 times repectively. Throughout the greening treatment, the GS and GOGAT activities were always high enough to sustain the expected rate of photorespiratory NH3 production. In contrast, glutamate dehydrogenase activity decreased during greening, and its measured rate was not high enough for photorespirtory NH3 assimilation. These results support the idea that the GS/GOGAT pathway is the major, if not the only, route for photorespiratory NH3 assimilation in the light in leaves of higher plants.

Primary nitrogen assimilation in higher plants and its regulation

1994 ◽  
Vol 72 (6) ◽  
pp. 739-750 ◽  
Author(s):  
Ann Oaks
Keyword(s):  
Nitrogen Assimilation ◽  
Higher Plants ◽  
Nitrate Assimilation ◽  
Glutamate Synthase ◽  
Ammonium Assimilation ◽  
Cellular Organization ◽  
Nitrite Reductases ◽  
Leaf Tissues ◽  
Nitrate And Nitrite ◽  
Key Words Nitrate

Characteristics of the enzymes involved in the assimilation of NO3− and NH4+, in particular the nitrate and nitrite reductases, glutamine synthetase, glutamate synthase, glutamate dehydrogenase, glutamate decarboxylase, and asparagine synthetase, are described. The cellular organization of these enzymes in root and leaf tissues are assessed in view of recent research developments that utilize various tissue blotting techniques. Regulation of nitrate assimilation is analyzed at the physiological, biochemical, and molecular levels. Key words: nitrate, ammonium, assimilation, regulation.

Signalling cascades integrating light-enhanced nitrate metabolism

2008 ◽  
Vol 415 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Cathrine Lillo
Keyword(s):  
Protein Kinase ◽  
Higher Plants ◽  
Protein A ◽  
Reducing Power ◽  
Glutamate Synthase ◽  
Photosynthetic Electron Transport ◽  
Transcriptional Level ◽  
Signalling Cascades ◽  
Tightly Coupled ◽  
Nitrate Metabolism

In higher plants, light is crucial for regulation of nitrate uptake, translocation and assimilation into organic compounds. Part of this metabolism is tightly coupled to photosynthesis because the enzymes involved, nitrite reductase and glutamate synthase, are localized to the chloroplasts and receive reducing power from photosynthetic electron transport. However, important enzymes in nitrate acquisition and reduction are localized to cellular compartments other than chloroplasts and are also up-regulated by light, i.e. transporters in cell and organellar membranes and nitrate reductase in the cytosol. This review describes the different light-dependent signalling cascades regulating nitrate metabolism at the transcriptional as well as post-transcriptional level, and how reactions in different compartments of the cell are co-ordinated. Essential players in this network are phytochrome and HY5 (long hypocotyls 5)/HYH (HY5 homologue)-dependent signalling pathways, the energy-related AMPK (AMP-activated protein kinase) protein kinase homologue SNRK1 (sucrose non-fermenting kinase 1-related kinase), chloroplastic thioredoxins and the prokaryotically originated PII protein. A complex light-dependent network of regulation emerges, which appears to be necessary for optimal nitrogen assimilation and for avoiding the accumulation of toxic intermediates and side products, such as nitrite and reactive oxygen compounds.

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