Glutamine synthetase

glutamate-ammonia ligaseGLULGS
Glutamine synthetase (GS) is an enzyme that plays an essential role in the metabolism of nitrogen by catalyzing the condensation of glutamate and ammonia to form glutamine:wikipedia
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wasteful oxygenationphotorespiratoryphotorespiratory reactions
Glutamine Synthetase uses ammonia produced by nitrate reduction, amino acid degradation, and photorespiration.
The assimilation of NH 3 occurs via the GS-GOGAT cycle, at a cost of one ATP and one NADPH.

Methionine sulfoximine

Methionine sulfoximine (MSO): MSO is an inhibitor that binds to the glutamate site. Bound to GS, MSO is phosphorylated by ATP that results in an irreversible, non-covalent inhibition of GS. The S-isomer configuration is more inhibitory. Glutamate entry is blocked into the active site by a stabilization of the flexible loop in the active site by MSO.
Methionine sulfoximine (MSO) is an irreversible glutamine synthetase inhibitor.


phosphinothricinglufosinate ammonium
Phosphinothricin (PPT, Glufosinate): Phosphinothricin is an inhibitor that binds to the glutamate site. Glufosinate is used as an herbicide. Glufosinate treated plants die due to a buildup of ammonia and a cessation of photosynthesis.
The compound irreversibly inhibits glutamine synthetase, an enzyme necessary for the production of glutamine and for ammonia detoxification, giving it antibacterial, antifungal and herbicidal properties.


GlnQ L -glutamine
Glutamine synthetase (GS) is an enzyme that plays an essential role in the metabolism of nitrogen by catalyzing the condensation of glutamate and ammonia to form glutamine:
Glutamine is synthesized by the enzyme glutamine synthetase from glutamate and ammonia.


Tyr 397 of all 12 subunits can undergo adenylylation or deadenylylation by adenylyl transferase (AT), a bifunctional regulatory enzyme.
Similar to serine, threonine or tyrosine phosphorylation, AMPylation regulates the activity of some proteins, such as glutamine synthetase.

NsiR4 small RNA

These inactivating factors are furthermore regulated by different Non-coding RNAs: The sRNA NsiR4 interacts with the 5'UTR of the mRNA of the GS inactivating factor IF7 ( gifA mRNA) and reduces its expression.
NsiR4 (nitrogen stress-induced RNA 4), former name SyR12, is a cyanobacterial non-coding RNA which plays role in the regulation of Glutamine synthetase (GS), a key enzyme in biological nitrogen assimilation.

GlnA RNA motif

glutamine-binding riboswitchglutamine riboswitch
In addition, expression of the GS inactivating factor IF17 is controlled by a glutamine-binding riboswitch.
The most prominent of these protein classes are ammonium transporters, the enzymes glutamine synthetase and glutamate synthase and P II protein, which itself regulates nitrogen metabolism.


* Methionine sulfoximine, a chemical compound that inhibits glutamine synthetase irreversibly

GlnALG operon

glnA encodes glutamine synthetase, an enzyme which catalyzes the conversion of glutamate and ammonia to glutamine, thereby controlling the nitrogen level in the cell.


Lengsin is a survivor of an ancient family of class I glutamine synthetases in eukaryotes that has undergone evolutionary re-engineering for a tissue-specific, noncatalytic role in the lens of the vertebrate eye.


Analysis of glutamine synthetase sequence has been suggested for phylogenetic analysis of the Actinobacteria.

Nitrogen fixation

nitrogen-fixingfix nitrogennitrogen fixing
In free-living diazotrophs, the nitrogenase-generated ammonia is assimilated into glutamate through the glutamine synthetase/glutamate synthase pathway.The microbial genes required for nitrogen fixation are widely distributed in diverse environments.

Glutamate-glutamine cycle

glutamine-glutamate shuttle
Astrocytes readily convert glutamate to glutamine via the glutamine synthetase pathway and released into the extracellular space.

Glutamine oxoglutarate aminotransferase

glutamate synthaseglutamate synthetaseGOGAT
Glutamine oxoglutarate aminotransferase (also known as Glutamate synthase) is an enzyme and frequently abbreviated as GOGAT. This enzyme manufactures glutamate from glutamine and α-ketoglutarate, and thus along with glutamine synthetase (abbreviated GS) plays a central role in the regulation of nitrogen assimilation in photosynthetic eukaryotes and prokaryotes.

Penicillin binding proteins

penicillin-binding proteinspenicillin-binding proteinpenicillin binding protein
All β-lactam antibiotics (except for tabtoxinine-β-lactam, which inhibits glutamine synthetase) bind to PBPs, which are essential for bacterial cell wall synthesis.

Pseudomonas sRNA P1

There appears to be two related copies of P1 sRNA in the P. aeruginosa PA01 genome and both copies appear to be located upstream of predicted glutamine synthetase genes.

Satellite glial cell

satellite cells
Many people liken SGCs to the astrocytes of the CNS because they share certain anatomical and physiological properties, such as the presence of neurotransmitter transporters and the expression of glutamine synthetase.

Nitrogen assimilation

assimilation of nitratesassimilationabsorbing
Ammonia (both absorbed and synthesized) is incorporated into amino acids via the glutamine synthetase-glutamate synthase (GS-GOGAT) pathway.


Archaea and gram-positive bacteria also share conserved indels in a number of important proteins, such as Hsp70 and glutamine synthetase I;, but the phylogeny of these genes was interpreted to reveal interdomain gene transfer, and might not reflect the organismal relationship(s).

Boyd Haley

In 1992, Haley and a colleague, upon examining cerebrospinal fluid, reported levels of glutamine synthetase considerably higher in cases of Alzheimer's disease than in a control group, and suggested that this could be a biomarker to aid diagnosis.

(glutamate—ammonia-ligase) adenylyltransferase

Thus, the two substrates of this enzyme are ATP and L-glutamate:ammonia ligase (ADP-forming), whereas its two products are diphosphate and adenylyl-[L-glutamate:ammonia ligase (ADP-forming)].

Multienzyme complex

Examples include pyruvate dehydrogenase, fatty acid synthetase, glutamine synthetase, proteasome, rubisco.