Disease relevance of glnA

• Plant glutamine synthetase complements a glnA mutation in Escherichia coli [1].
• We have determined the nucleotide sequences of the Klebsiella pneumoniae nifL (regulation of N2 fixation genes) and the Escherichia coli glnA (glutamine synthetase) promoters [2].
• The NtrC protein activates transcription of the glnA operon of enteric bacteria by stimulating the formation of stable "open" complexes by RNA polymerase (sigma 54-holoenzyme form) [3].
• Studies on Clostridium acetobutylicum glnA promoters and antisense RNA [4].
• Pseudanabaena sp. strain PCC 6903 is the first cyanobacteria lacking the typical prokaryotic glutamine synthetase type I encoded by the glnA gene [5].

High impact information on glnA

• Alfalfa NADH-dependent glutamate synthase (NADH-GOGAT), together with glutamine synthetase, plays a central role in the assimilation of symbiotically fixed nitrogen into amino acids in root nodules [6].
• Furthermore, the ammonia-enhanced GS gene expression in L. corniculatus is due to an increase in transcription [7].
• A full-length cDNA clone encoding cytosolic glutamine synthetase (GS), expressed in roots and root nodules of soybean, was isolated by direct complementation of an Escherichia coli gln A- mutant [7].
• However, the pH profiles of tyrosine nitration in GS and BSA are not the same [8].
• The ability of peroxynitrite to modify amino acid residues in glutamine synthetase (GS) and BSA is greatly influenced by pH and CO2 [8].

Chemical compound and disease context of glnA

• E. coli delta glnA cells were transformed with cDNA library plasmid DNA, grown briefly in rich medium to allow phenotypic expression of the cDNAs and the pUC13 ampr gene, and challenged to grow on agar medium lacking glutamine [9].
• However, WSU650, a Rhizobium meliloti glnA glnII mutant that lacks both enzymes, can grow without a glutamine supplement in minimal medium that contains both ammonium and glutamate [10].
• A diauxic growth pattern was obtained when E. coli was grown on a low concentration of ammonia in combination with arginine as a nitrogen source, consistent with the hypothesis that Ntr genes other than glnA become activated only upon amplification of the NRI concentration [11].
• Treatment of Escherichia coli glutamine synthetase (GS) with peroxynitrite leads to nitration of some tyrosine residues and conversion of some methionine residues to methionine sulfoxide (MSOX) residues [12].
• Escherichia coli glutamine synthetase (GS) was inactivated by a nonenzymic mixed-function oxidation system composed of ascorbate, O2, and Fe(III) [13].

Biological context of glnA

• To regulate the glnA promoter, NtrC binds to sites that have the properties of transcriptional enhancers: the sites will function far from the promoter and in an orientation-independent fashion [3].
• In vivo "footprints" of the glnA regulatory region under activating conditions demonstrate that the three most upstream activator sequences bind the protein NRI in the cell [14].
• The DNA template was a 726 bp linear fragment with two NtrC binding sites located at the end and about 460 bp away from the RNAP x sigma 54 glnA promoter [15].
• Scanning force microscopy (SFM) was used to visualize complexes of Escherichia coli RNA polymerase.sigma54 (RNAP.sigma54) and a 1036 base-pair linear DNA fragment containing the glnA promoter [16].
• Scanning force microscopy (SFM) has been used to study transcriptional activation of Escherichia coli RNA polymerase x sigma 54 (RNAP x sigma 54) at the glnA promoter by the constitutive mutant NtrC(D54E,S160F) of the NtrC Protein (nitrogen regulatory protein C) [15].

Anatomical context of glnA

• Surprisingly, about 40% of the plastid GS in nodules occurred in the non-processed precursor form (preGS2) [17].
• DNA encoding the N-terminal 415 residues of the human thyrotrophin receptor (predicted to code for the large extracellular region) was introduced into Chinese hamster ovary (CHO) cells using the glutamine synthetase/cytomegalovirus amplifiable expression system, and into E. coli using the pGEX-3X expression vector [18].
• Both the kinetics and the extent of glutamine synthetase inactivation differ when neutrophils are stimulated with phorbol esters compared with formylated peptides [19].
• Also, if endogenous catalase is inhibited by azide, rabbit liver microsomes catalyze the inactivation of glutamine synthetase [20].
• Expression of GS in E. coli under transcriptional regulation of T5 promoter yielded an insoluble protein aggregating to form inclusion bodies [21].

Associations of glnA with chemical compounds

• An alternative pathway involves the combined activities of glutamine synthetase, which aminates glutamate to form glutamine, and glutamate synthase, which transfers the amide group of glutamine to 2-oxoglutarate to yield two molecules of glutamate [22].
• The 2-kbp fragment restored glutamine-independent growth and ammonia repression of nitrogenase, indicating that in R. capsulata, production of the signal for nitrogen repression of nif depends on the activity of the glnA gene [23].
• A deletion introduced at the binding site of the NtcA regulatory protein abolished derepression of the glnA promoter during growth in nitrate and under nitrogen starvation [24].
• Isotopic labelling experiments with 15N-labelled ammonium sulfate demonstrated that wild-type Eh1087 incorporated 15N into griseoluteic acid more readily than the glnA mutant Eh7 [25].
• With glutamine as nitrogen source, high levels of glnA and glnK expression were obtained when glucose was used as carbon source, but expression was strongly decreased when the cells were grown with poor carbon sources or when cAMP was present [26].

Other interactions of glnA

• In Escherichia coli, the glnA and glnG genes are transcribed in the same direction [27].
• The nac enhancer, consisting of a single high-affinity NRI-binding site and an adjacent site with low affinity for NRI, was less efficient in stimulating transcription than was the glnA enhancer, which consists of two adjacent high-affinity NRI-binding sites [28].

Analytical, diagnostic and therapeutic context of glnA

• An electrophoretic mobility shift assay demonstrated that S. violacea sigma(54) specifically binds to the promoter region of glnA, suggesting that sigma(54) may play an important role in pressure-regulated transcription in this piezophilic bacterium [29].
• Synthesis of the alfalfa glutamine synthetase enzyme in Escherichia coli was demonstrated by functional genetic complementation of a glutamine synthetase-deficient mutant and by immunoblotting analysis [1].
• Localization of the site of adenylylation of glutamine synthetase by electron microscopy of an enzyme-antibody complex [30].
• Metal-dependent self-assembly of protein tubes from Escherichia coli glutamine synthetase. Cu(2+) EPR studies of the ligation and stoichiometry of intermolecular metal binding sites [31].
• Using immunoprecipitation techniques, we have determined the rates at which rhodanese and glutamine synthetase (GS) are released from groEL in a form committed to refold to active enzyme [32].

References