F
IPR002187

Nitrogen regulatory protein PII

InterPro entry
Short nameN-reg_PII
Overlapping
homologous
superfamilies
 

Description

In Gram-negative bacteria, the activity and concentration of glutamine synthetase (GS) is regulated in response to nitrogen source availability. PII, a tetrameric protein encoded by the glnB gene, is a component of the adenylation cascade involved in the regulation of GS activity
[1]
. In nitrogen-limiting conditions, when the ratio of glutamine to 2-ketoglutarate decreases, P-II is uridylylated on a tyrosine residue to form P-II-UMP. P-II-UMP allows the deadenylation of GS, thus activating the enzyme. Conversely, in nitrogen excess, P-II-UMP is deuridylated and then promotes the adenylation of GS. P-II also indirectly controls the transcription of the GS gene (glnA) by preventing NR-II (ntrB) to phosphorylate NR-I (ntrC) which is the transcriptional activator of glnA. Once P-II is uridylylated, these events are reversed.

P-II is a protein of about 110 amino acid residues extremely well conserved. The tyrosine which is uridylated is located in the central part of the protein. In cyanobacteria, P-II seems to be phosphorylated on a serine residue rather than being uridylated. In methanogenic archaebacteria, the nitrogenase iron protein gene (nifH) is followed by two open reading frames highly similar to the eubacterial P-II protein
[2]
. These proteins could be involved in the regulation of nitrogen fixation. In the red alga, Porphyra purpurea, there is a glnB homologue encoded in the chloroplast genome.

Other proteins highly similar to glnB are:


 * Bacillus subtilis protein nrgB
[3]
.
 * Escherichia coli hypothetical protein ybaI
[4]
.
 * GlnK from Archaea and bacteria, an homologue of GlnB protein, which regulates ammonium transport (Amt) proteins
[5, 6]


References

1.Characterization of three different nitrogen-regulated promoter regions for the expression of glnB and glnA in Azospirillum brasilense. de Zamaroczy M, Delorme F, Elmerich C. Mol. Gen. Genet. 224, 421-30, (1990). View articlePMID: 1702507

2.Nucleotide sequence of nifH regions from Methanobacterium ivanovii and Methanosarcina barkeri 227 and characterization of glnB-like genes. Sibold L, Henriquet M, Possot O, Aubert JP. Res. Microbiol. 142, 5-12, (1991). View articlePMID: 2068380

3.The nitrogen-regulated Bacillus subtilis nrgAB operon encodes a membrane protein and a protein highly similar to the Escherichia coli glnB-encoded PII protein. Wray LV Jr, Atkinson MR, Fisher SH. J. Bacteriol. 176, 108-14, (1994). View articlePMID: 8282685

4.Cloning and organization of the abc and mdl genes of Escherichia coli: relationship to eukaryotic multidrug resistance. Allikmets R, Gerrard B, Court D, Dean M. Gene 136, 231-6, (1993). View articlePMID: 7904973

5.Mechanism of disruption of the Amt-GlnK complex by P(II)-mediated sensing of 2-oxoglutarate. Maier S, Schleberger P, Lu W, Wacker T, Pfluger T, Litz C, Andrade SL. PLoS ONE 6, e26327, (2011). View articlePMID: 22039461

6.Structure of GlnK1 with bound effectors indicates regulatory mechanism for ammonia uptake. Yildiz O, Kalthoff C, Raunser S, Kuhlbrandt W. EMBO J. 26, 589-99, (2007). View articlePMID: 17203075

GO terms

cellular component

  • None

Cross References

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