ABSTRACT
The enzyme responsible for glutamine production, glutamine synthetase, is widely distributed in microorganisms, plants, and animals and catalyzes. The conversion of glutamate and ammonia to glutamine with the cleavage of ATP to ADP and Pi Glutamine synthetase occupies a central position in cell physiology, because it forms an intersection of pathways for carbon metabolism, ammonia assimilation, amino acid synthesis, and the availability of glutamate and glutamine as precursors for other cell constituents. The glutamine synthetase from Escherichia coli has been extensively studied and the information reviewed. The activity of glutamine synthetase from the enteric bacteria can be regulated through feedback inhibition by numerous products of glutamine metabolism, by the presence of divalent metal ions, and by covalent modification involving the adenylylation and deadenylylation of a tyrosyl residue on each subunit. These reactions are delicately balanced by cell physiology and may have different roles in changing glutamine synthetase activity.
