Abstract
It has previously been shown that phosphorylated nitrogen regulator I (NRi-phosphate) is the activator responsible for increasing the transcription of glnA, the structural gene for glutamine synthetase, and that NRII catalyzes the transfer of the .gamma.-phosphate of ATP to NRI. We have now shown that the reaction of ATP with NRII results in the reversible transfer of the .gamma.-phosphate of ATP to a histidine residue of NRII. In turn, NRII-phosphate transfer its phosphate reversibly to an aspartic residue of NRI-phosphate is hydrolyzed to NRI and inorganic phosphate in a divalent cation-requiring autocatalytic reaction.