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MetaCyc Pathway: superpathway of ammonia assimilation (plants)
Traceable author statement to experimental support

Enzyme View:

Pathway diagram: superpathway of ammonia assimilation (plants)

This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.

Synonyms: GS/GOGAT pathway

Superclasses: Degradation/Utilization/AssimilationInorganic Nutrients MetabolismNitrogen Compounds MetabolismAmmonia Assimilation

Some taxa known to possess this pathway include : Arabidopsis thaliana col, Lupinus angustifolius, Oryza sativa, Pisum sativum, Vitis vinifera, Zea mays

Expected Taxonomic Range: Viridiplantae

The primary nitrogen assimilation routes in photosynthetic eukaryotes and prokaryotes are nitrogen fixation, nitrate assimilation, and ammonia assimilation. Ammonia is liberated by photorespiration, protein and amino acid metabolism, and the breakdown of nitrogen transport compounds. The rate of ammonia generation during photorespiration is about 10 times the rate of nitrate assimilation.

The ammonia released from photorespiration is immediately re-assimilated via the ammonia assimilation cycle. The net result of this cycle is the conversion of one molecule of ammonia to one molecule of glutamate at the expense of one ATP molecule.

The pathway includes two steps catalyzed by glutamine synthetase (GS) and glutamate synthase (also known as glutamine oxoglutarate aminotansferase or GOGAT), and thus is often referred to as the GS/GOGAT pathway. Two types of GOGAT are known in photosynthetic organisms - NADH-dependent, and ferredoxin-dependent. NADH-GOGAT is found in the nucleus of vascular plants, fungi, and diatoms. The ferredoxin-dependent enzyme is only found in Cyanobacteria and photosynthetic eukaryotes. Plants possess both enzymes.

An NADPH-dependent version of GOGAT is found in non-photosynthetic bacteria and archaea (see ammonia assimilation cycle III).

Citations: [Miflin02]

Subpathways: ammonia assimilation cycle II, ammonia assimilation cycle I, L-glutamine biosynthesis I, L-glutamate biosynthesis IV

Variants: ammonia assimilation cycle III

Unification Links: AraCyc:PWY-3282

Revised 08-Dec-2011 by Caspi R, SRI International


Miflin02: Miflin BJ, Habash DZ (2002). "The role of glutamine synthetase and glutamate dehydrogenase in nitrogen assimilation and possibilities for improvement in the nitrogen utilization of crops." J Exp Bot 53(370);979-87. PMID: 11912240

Other References Related to Enzymes, Genes, Subpathways, and Substrates of this Pathway

Alibhai94: Alibhai M, Villafranca JJ (1994). "Kinetic and mutagenic studies of the role of the active site residues Asp-50 and Glu-327 of Escherichia coli glutamine synthetase." Biochemistry 33(3);682-6. PMID: 7904829

Amaya05: Amaya KR, Kocherginskaya SA, Mackie RI, Cann IK (2005). "Biochemical and mutational analysis of glutamine synthetase type III from the rumen anaerobe Ruminococcus albus 8." J Bacteriol 187(21);7481-91. PMID: 16237031

Avendano97: Avendano A, Deluna A, Olivera H, Valenzuela L, Gonzalez A (1997). "GDH3 encodes a glutamate dehydrogenase isozyme, a previously unrecognized route for glutamate biosynthesis in Saccharomyces cerevisiae." J Bacteriol 179(17);5594-7. PMID: 9287019

Balakrishnan78: Balakrishnan MS, Villafranca JJ (1978). "Distance determinations between the metal ion sites of Escherichia coli glutamine synthetase by electron paramagnetic resonance using Cr(III)--nucleotides as paramagnetic substrate analogues." Biochemistry 17(17);3531-8. PMID: 28753

Bender77: Bender RA, Janssen KA, Resnick AD, Blumenberg M, Foor F, Magasanik B (1977). "Biochemical parameters of glutamine synthetase from Klebsiella aerogenes." J Bacteriol 129(2);1001-9. PMID: 14104

Benjamin89: Benjamin PM, Wu JI, Mitchell AP, Magasanik B (1989). "Three regulatory systems control expression of glutamine synthetase in Saccharomyces cerevisiae at the level of transcription." Mol Gen Genet 217(2-3);370-7. PMID: 2570348

Boland77: Boland MJ, Benny AG (1977). "Enzymes of nitrogen metabolism in legume nodules. Purification and properties of NADH-dependent glutamate synthase from lupin nodules." Eur J Biochem 79(2);355-62. PMID: 21790

BRENDA14: BRENDA team (2014). Imported from BRENDA version existing on Aug 2014.

Cogoni95: Cogoni C, Valenzuela L, Gonzalez-Halphen D, Olivera H, Macino G, Ballario P, Gonzalez A (1995). "Saccharomyces cerevisiae has a single glutamate synthase gene coding for a plant-like high-molecular-weight polypeptide." J Bacteriol 177(3);792-8. PMID: 7836314

CohenKupiec93: Cohen-Kupiec R, Gurevitz M, Zilberstein A (1993). "Expression of glnA in the cyanobacterium Synechococcus sp. strain PCC 7942 is initiated from a single nif-like promoter under various nitrogen conditions." J Bacteriol 175(23);7727-31. PMID: 7902350

Coschigano98: Coschigano KT, Melo-Oliveira R, Lim J, Coruzzi GM (1998). "Arabidopsis gls mutants and distinct Fd-GOGAT genes. Implications for photorespiration and primary nitrogen assimilation." Plant Cell 10(5);741-52. PMID: 9596633

Dahlquist75: Dahlquist FW, Purich DL (1975). "Regulation of Escherichia coli glutamine synthetase. Evidence for the action of some feedback modifiers at the active site of the unadenylylated enzyme." Biochemistry 14(9);1980-9. PMID: 235974

Dhalla94: Dhalla AM, Li B, Alibhai MF, Yost KJ, Hemmingsen JM, Atkins WM, Schineller J, Villafranca JJ (1994). "Regeneration of catalytic activity of glutamine synthetase mutants by chemical activation: exploration of the role of arginines 339 and 359 in activity." Protein Sci 3(3);476-81. PMID: 7912599

Esposito05: Esposito S, Guerriero G, Vona V, Di Martino Rigano V, Carfagna S, Rigano C (2005). "Glutamate synthase activities and protein changes in relation to nitrogen nutrition in barley: the dependence on different plastidic glucose-6P dehydrogenase isoforms." J Exp Bot 56(409);55-64. PMID: 15501908

Farrington87: Farrington GK, Kumar A, Wedler FC (1987). "Design and synthesis of phosphonate inhibitors of glutamine synthetase." J Med Chem 1987;30(11);2062-7. PMID: 2889829

Filetici96: Filetici P, Martegani MP, Valenzuela L, Gonzalez A, Ballario P (1996). "Sequence of the GLT1 gene from Saccharomyces cerevisiae reveals the domain structure of yeast glutamate synthase." Yeast 12(13);1359-66. PMID: 8923741

Gibbs84: Gibbs EJ, Ransom SC, Cuppett S, Villafranca JJ (1984). "Mn-Mn interaction in adenylylated and unadenylylated glutamine synthetase." Biochem Biophys Res Commun 120(3);939-45. PMID: 6145412

Gottschalk86: Gottschalk, G "Bacterial Metabolism, Second Edition." Springer-Verlag, New York. 1986.

Gregerson93: Gregerson RG, Miller SS, Twary SN, Gantt JS, Vance CP (1993). "Molecular characterization of NADH-dependent glutamate synthase from alfalfa nodules." Plant Cell 5(2);215-26. PMID: 8453303

Hayakawa93: Hayakawa T, Yamaya T, Mae T, Ojima K (1993). "Changes in the Content of Two Glutamate Synthase Proteins in Spikelets of Rice (Oryza sativa) Plants during Ripening." Plant Physiol 101(4);1257-1262. PMID: 12231780

Showing only 20 references. To show more, press the button "Show all references".

Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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