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: L-glutamine - L-glutamate pathway
|Superclasses:||Biosynthesis → Amino Acids Biosynthesis → Proteinogenic Amino Acids Biosynthesis → L-glutamine Biosynthesis|
|Degradation/Utilization/Assimilation → Inorganic Nutrients Metabolism → Nitrogen Compounds Metabolism → Ammonia Assimilation|
Some taxa known to possess this pathway include : Escherichia coli K-12 substr. MG1655, Haloferax mediterranei, Homo sapiens, Ruminococcus albus 8, Saccharomyces cerevisiae, Synechococcus elongatus PCC 7942
The amino acid glutamine is a constituent of proteins and a nitrogen donor for many biosynthetic reactions, including the biosynthesis of amino acids, purines, pyrimidines, glucosamime and carbamoyl phosphate. The biosynthesis of glutamine is catalyzed by glutamine synthetase, a key enzyme of nitrogen metabolism found in all domains of life. Phylogenetic analysis of glutamine synthetase genes has suggested that they are among the oldest functioning genes in the history of evolution [Kumada93]. In microorganisms and plants, glutamine synthetase (also known as GS) has a role in ammonia assimilation in combination with glutamate synthase (glutamine: α-oxoglutarate aminotransferase, or GOGAT) as indicated by the pathway links and pathways ammonia assimilation cycle III and superpathway of ammonia assimilation (plants)). This is known as the GS/GOGAT pathway [Gottschalk86].
About this pathway
Three types of glutamine synthetases have been described, differing in number of subunits. The active site residues of all three types are conserved.
Glutamine synthetase type I is found mostly in bacteria and archaea, including Escherichia coli K-12 and Salmonella enterica enterica serovar Typhimurium (reviewed in [Stadtman01]). It is a well-studied homododecamer built from two back-to-back hexameric rings.
Glutamine synthetase type II is found mostly in eukaryotes and some soil bacteria, but it has also been described in the halophilic archaeon Haloferax mediterranei [MartinezEspinos06, Llorca06]. It is a homooctamer.
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
Kumada93: Kumada Y, Benson DR, Hillemann D, Hosted TJ, Rochefort DA, Thompson CJ, Wohlleben W, Tateno Y (1993). "Evolution of the glutamine synthetase gene, one of the oldest existing and functioning genes." Proc Natl Acad Sci U S A 90(7);3009-13. PMID: 8096645
Llorca06: Llorca O, Betti M, Gonzalez JM, Valencia A, Marquez AJ, Valpuesta JM (2006). "The three-dimensional structure of an eukaryotic glutamine synthetase: functional implications of its oligomeric structure." J Struct Biol 156(3);469-79. PMID: 16884924
MartinezEspinos06: Martinez-Espinosa RM, Esclapez J, Bautista V, Bonete MJ (2006). "An octameric prokaryotic glutamine synthetase from the haloarchaeon Haloferax mediterranei." FEMS Microbiol Lett 264(1);110-6. PMID: 17020556
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
Atkins92: Atkins WM, Villafranca JJ (1992). "Time-resolved fluorescence studies of tryptophan mutants of Escherichia coli glutamine synthetase: conformational analysis of intermediates and transition-state complexes." Protein Sci 1(3);342-55. PMID: 1363912
Atkins94: Atkins WM (1994). "Supramolecular self-assembly of Escherichia coli glutamine synthetase: effects of pressure and adenylylation state on dodecamer stacking." Biochemistry 33(50);14965-73. PMID: 7999752
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
Bennett09: Bennett BD, Kimball EH, Gao M, Osterhout R, Van Dien SJ, Rabinowitz JD (2009). "Absolute metabolite concentrations and implied enzyme active site occupancy in Escherichia coli." Nat Chem Biol 5(8);593-9. PMID: 19561621
Bruggeman05: Bruggeman FJ, Boogerd FC, Westerhoff HV (2005). "The multifarious short-term regulation of ammonium assimilation of Escherichia coli: dissection using an in silico replica." FEBS J 272(8);1965-85. PMID: 15819889
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
Colanduoni87: Colanduoni J, Nissan R, Villafranca JJ (1987). "Studies of the mechanism of glutamine synthetase utilizing pH-dependent behavior in catalysis and binding." J Biol Chem 262(7);3037-43. PMID: 2880845
Dabrowski94: Dabrowski MJ, Yanchunas J, Villafranca BC, Dietze EC, Schurke P, Atkins WM (1994). "Supramolecular self-assembly of glutamine synthetase: mutagenesis of a novel intermolecular metal binding site required for dodecamer stacking." Biochemistry 33(50);14957-64. PMID: 7999751
Dabrowski96: Dabrowski MJ, Dietze EC, Atkins WM (1996). "Engineering the aggregation properties of dodecameric glutamine synthetase: a single amino acid substitution controls 'salting out'." Protein Eng 9(3);291-8. PMID: 8736496
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
DautryVarsat79: Dautry-Varsat A, Cohen GN, Stadtman ER (1979). "Some properties of Escherichia coli glutamine synthetase after limited proteolysis by subtilisin." J Biol Chem 254(8);3124-8. PMID: 34613
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
DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114
Fisher92: Fisher MT, Stadtman ER (1992). "Oxidative modification of Escherichia coli glutamine synthetase. Decreases in the thermodynamic stability of protein structure and specific changes in the active site conformation." J Biol Chem 267(3);1872-80. PMID: 1346137
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