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Pathway Description
Nitrogen Metabolism
Escherichia coli
Metabolic Pathway
Nitrogen and nitrogen cycle play an important role in biological process for many microorganisms as catalyzing different reactions. For example, nitrate reduction is used for conversion into ammonia and denitrification, where denitrification is an important cellular respiration process. Nitrogenase enzyme in prokaryotes can fix the atmospheric nitrogen by catalyzing nitrogen fixation (i.e. reduction of nitrogen to ammonia). Nitrate can be introduced into the cytoplasm through a nitrate:nitrite antiporter NarK or a nitrate/nitrite transporter NarU. Nitrate is then reduced by a nitrate reductase resulting in the release of water, an acceptor, and a nitrite. Nitrite can also be introduced into the cytoplasm through a nitrate:nitrite antiporter NarK. Nitrite can be reduced by an NADPH-dependent nitrite reductase resulting in water, NAD, and ammonia. Nitrite can interact with a hydrogen ion and ferrocytochrome c through a cytochrome c-552 ferricytochrome resulting in the release of ferricytochrome c, water, and ammonia. Another process by which ammonia is produced is by a reversible reaction of hydroxylamine with a reduced acceptor through a hydroxylamine reductase. This results in an acceptor, water, and ammonia. Water and carbon dioxide react through a carbonate dehydratase resulting in carbamic acid. This compound reacts spontaneously with hydrogen ion resulting in the release of carbon dioxide and ammonia. Carbon dioxide can interact with water through a carbonic anhydrase resulting in hydrogen carbonate. This compound interacts with cyanate and hydrogen ion through a cyanate hydratase resulting in a carbamic acid. Ammonia can be metabolized by reacting with L-glutamine and ATP-driven glutamine synthetase resulting in ADP, phosphate, and L-glutamine. The latter compound reacts with oxoglutaric acid and hydrogen ion through an NADPH-dependent glutamate synthase resulting in the release of NADP and L-glutamic acid. L-Glutamic acid reacts with water through an NADP-specific glutamate dehydrogenase resulting in the release of oxoglutaric acid, NADPH, hydrogen ion, and ammonia.
References
Nitrogen Metabolism References
Adler SP, Purich D, Stadtman ER: Cascade control of Escherichia coli glutamine synthetase. Properties of the PII regulatory protein and the uridylyltransferase-uridylyl-removing enzyme. J Biol Chem. 1975 Aug 25;250(16):6264-72.
Pubmed: 239942
Alibhai M, Villafranca JJ: Kinetic and mutagenic studies of the role of the active site residues Asp-50 and Glu-327 of Escherichia coli glutamine synthetase. Biochemistry. 1994 Jan 25;33(3):682-6.
Pubmed: 7904829
Atkins WM, Villafranca JJ: Time-resolved fluorescence studies of tryptophan mutants of Escherichia coli glutamine synthetase: conformational analysis of intermediates and transition-state complexes. Protein Sci. 1992 Mar;1(3):342-55. doi: 10.1002/pro.5560010306.
Pubmed: 1363912
Atkins WM: Supramolecular self-assembly of Escherichia coli glutamine synthetase: effects of pressure and adenylylation state on dodecamer stacking. Biochemistry. 1994 Dec 20;33(50):14965-73.
Pubmed: 7999752
Atkinson MR, Kamberov ES, Weiss RL, Ninfa AJ: Reversible uridylylation of the Escherichia coli PII signal transduction protein regulates its ability to stimulate the dephosphorylation of the transcription factor nitrogen regulator I (NRI or NtrC). J Biol Chem. 1994 Nov 11;269(45):28288-93.
Pubmed: 7961766
Atkinson MR, Ninfa AJ: Role of the GlnK signal transduction protein in the regulation of nitrogen assimilation in Escherichia coli. Mol Microbiol. 1998 Jul;29(2):431-47.
Pubmed: 9720863
Atkinson MR, Ninfa AJ: Characterization of the GlnK protein of Escherichia coli. Mol Microbiol. 1999 Apr;32(2):301-13.
Pubmed: 10231487
Balakrishnan MS, Villafranca JJ: 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. 1978 Aug 22;17(17):3531-8.
Pubmed: 28753
Bender RA, Janssen KA, Resnick AD, Blumenberg M, Foor F, Magasanik B: Biochemical parameters of glutamine synthetase from Klebsiella aerogenes. J Bacteriol. 1977 Feb;129(2):1001-9.
Pubmed: 14104
Blauwkamp TA, Ninfa AJ: Physiological role of the GlnK signal transduction protein of Escherichia coli: survival of nitrogen starvation. Mol Microbiol. 2002 Oct;46(1):203-14.
Pubmed: 12366843
Bloom FR, Levin MS, Foor F, Tyler B: Regulation of glutamine synthetase formation in Escherichia coli: characterization of mutants lacking the uridylyltransferase. J Bacteriol. 1978 May;134(2):569-77.
Pubmed: 26660
Bruggeman FJ, Boogerd FC, Westerhoff HV: The multifarious short-term regulation of ammonium assimilation of Escherichia coli: dissection using an in silico replica. FEBS J. 2005 Apr;272(8):1965-85. doi: 10.1111/j.1742-4658.2005.04626.x.
Pubmed: 15819889
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