Recombinant Escherichia coli Nitrogen regulatory protein P-II 2 (glnK)

Involved in the regulation of nitrogen metabolism. Regulates the activity of its targets by protein-protein interaction in response to the nitrogen status of the cell. Involved in the regulation of the ammonium transporter AmtB so as to optimize ammonium uptake under all growth conditions. In nitrogen-limited conditions, GlnK does not interact with AmtB, which remains active and imports ammonium. When extracellular ammonium increases, GlnK associates tightly with AmtB in the inner membrane, thereby inhibiting the transporter activity. Also involved in the regulation of the glutamine synthetase adenylyltransferase/adenylyl-removing (AT/AR) enzyme GlnE and the glutamine synthetase GlnA. In nitrogen-limited conditions, formation of uridylylated GlnB(PII)/GlnK heterotrimers may fine-regulate the activation of GlnA: uridylylated heterotrimers stimulate the deadenylation and the activation of GlnA whereas uridylylated GlnK homotrimers do not stimulate, or hardly stimulate, the deadenylation of GlnA. In addition, regulates the expression of Ntr genes during nitrogen starvation, probably via the control of the levels of phosphorylated NRI during different stages of the response to nitrogen limitation.