Protein: Nitrogen regulatory protein GlnK (P0AC55)
Organism: Escherichia coli (strain K12)
Function: 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
Subcellular location: Cytoplasm. Cell inner membrane. Note=During nitrogen limitation, GlnK is predominantly in its fully uridylylated state in the cytoplasmic fraction. In response to nitrogen shock, GlnK is deuridylylated rapidly and associates tightly with AmtB in the inner membrane
Sequence: MKLVTVIIKPFKLEDVREALSSIGIQGLTVTEVKGFGRQKGHAELYRGAEYSVNFLPKVKIDVAIADDQLDEVIDIVSKAAYTGKIGDGKIFVAELQRVIRIRTGEADEAAL
InterPro domains: - IPR011322: Nitrogen regulatory PII-like, alpha/beta (homologous_superfamily) [1-112]
- IPR017918: Nitrogen regulatory protein PII, conserved site (conserved_site) [83-96]
- IPR002332: Nitrogen regulatory protein P-II, urydylation site (ptm) [46-51]
- IPR015867: Nitrogen regulatory protein PII/ATP phosphoribosyltransferase, C-terminal (homologous_superfamily) [1-112]
- IPR002187: Nitrogen regulatory protein PII (family) [1-112]
Interaction partners: - Ammonium transporter AmtB
- Sensory histidine kinase/phosphatase NtrB
- Bifunctional uridylyltransferase/uridylyl-removing enzyme
- Nitrogen assimilation regulatory protein nac
- DNA-binding transcriptional regulator NtrC
- Nitrogen regulatory protein P-II 1
- Glutamine synthetase
- Bifunctional glutamine synthetase adenylyltransferase/adenylyl-removing enzyme
- Glutamate synthase [NADPH] large chain
Gene Ontology annotations:
Molecular Function (MF): GO:0003674 (molecular function), GO:0005488 (binding), GO:0005515 (protein binding), GO:0042802 (identical protein binding)
Biological Process (BP): GO:0008150 (biological process), GO:0065007 (biological regulation), GO:0050789 (regulation of biological process), GO:0048583 (regulation of response to stimulus), GO:0065009 (regulation of molecular function), GO:0019222 (regulation of metabolic process), GO:0050794 (regulation of cellular process), GO:0032101 (regulation of response to external stimulus), GO:0050790 (regulation of catalytic activity), GO:0031323 (regulation of cellular metabolic process), GO:0080090 (regulation of primary metabolic process), GO:0009889 (regulation of biosynthetic process), GO:0062012 (regulation of small molecule metabolic process), GO:0046890 (regulation of lipid biosynthetic process), GO:0010565 (regulation of cellular ketone metabolic process), GO:0019216 (regulation of lipid metabolic process), GO:0032104 (regulation of response to extracellular stimulus), GO:0031326 (regulation of cellular biosynthetic process), GO:0042304 (regulation of fatty acid biosynthetic process), GO:0032107 (regulation of response to nutrient levels), GO:0019217 (regulation of fatty acid metabolic process), GO:0006808 (regulation of nitrogen utilization)
Cellular Component (CC): GO:0005575 (cellular component), GO:0110165 (cellular anatomical entity), GO:0005737 (cytoplasm), GO:0005829 (cytosol), GO:0005622 (intracellular anatomical structure)