Adenylyl-(glutamate—ammonia ligase) hydrolase

Adenylyl-(glutamate—ammonia ligase) hydrolase, also known as adenylylglutamine synthetase hydrolase (AGS hydrolase), is an enzyme that catalyzes the hydrolysis of adenylylated glutamine synthetase. Glutamine synthetase (GS) is a crucial enzyme involved in the assimilation of ammonia into glutamine. Its activity is tightly regulated in many organisms, often through adenylylation – the covalent attachment of an adenylyl group (AMP) to a specific tyrosine residue on the GS enzyme.

AGS hydrolase functions as the reverse reaction to adenylyltransferase (AT), which catalyzes the adenylylation of glutamine synthetase. AGS hydrolase removes the adenylyl group, thereby reactivating glutamine synthetase.

The regulation of glutamine synthetase activity via adenylylation/deadenylylation is a complex process influenced by various factors, including the levels of nitrogen, carbon, and energy within the cell. AGS hydrolase activity is often responsive to these same intracellular signals, allowing for fine-tuning of glutamine synthetase activity to meet the metabolic demands of the organism. The balance between adenylylation by adenylyltransferase and deadenylylation by AGS hydrolase determines the overall activity state of glutamine synthetase. The presence and activity of both AGS hydrolase and adenylyltransferase are key factors in the nitrogen regulatory pathways of bacteria and other organisms.