Involved in nitrogen metabolism via ammonium assimilation (PubMed:8002575). Catalyzes the ATP-dependent biosynthesis of glutamine from glutamate and ammonia (PubMed:1973929, PubMed:8002575). ATP + L-glutamate + NH4(+) = ADP + H(+) + L-glutamine + phosphate Binds 2 Mg(2+) ions per subunit (Ref.6). Also able to bind Co(2+), Mn(2+) and Ca(2+) ion (PubMed:1973929). Inhibited by ADP (90%), AMP (80%), alanine (52%) and aspartate (41%) (PubMed:1973929). The activity of this enzyme could be controlled by adenylation under conditions of abundant glutamine (By similarity). Optimum pH is 7.2. Optimum temperature is 35 degrees Celsius. Oligomer of 12 subunits arranged in the form of two hexagons. Highly expressed in nitrate- or ammonium-grown cells and exhibits two- to fourfold-higher expression in nitrogen-starved cells. Cells lacking this gene are able to grow with nitrate as the sole nitrogen source, but it are unable to grow in ammonium-containing medium. This mutant is impaired in the regulation of the nitrate assimilation system. Belongs to the glutamine synthetase family.