PMID:15157101
| Citation |
Song, Y, Peisach, D, Pioszak, AA, Xu, Z and Ninfa, AJ (2004) Crystal structure of the C-terminal domain of the two-component system transmitter protein nitrogen regulator II (NRII; NtrB), regulator of nitrogen assimilation in Escherichia coli. Biochemistry 43:6670-8 |
|---|---|
| Abstract |
The kinase/phosphatase nitrogen regulator II (NRII, NtrB) is a member of the transmitter protein family of conserved two-component signal transduction systems. The kinase activity of NRII brings about the phosphorylation of the transcription factor nitrogen regulator I (NRI, NtrC), causing the activation of Ntr gene transcription. The phosphatase activity of NRII results in the inactivation of NRI-P. The activities of NRII are regulated by the signal transduction protein encoded by glnB, PII protein, which upon binding to NRII inhibits the kinase and activates the phosphatase activity. The C-terminal ATP-binding domain of NRII is required for both the kinase and phosphatase activities and contains the PII binding site. Here, we present the crystal structure of the C-terminal domain of a mutant form of NRII, NRII-Y302N, at 1.6 A resolution and compare this structure to the analogous domains of other two-component system transmitter proteins. While the C-terminal domain of NRII shares the general tertiary structure seen in CheA, PhoQ, and EnvZ transmitter proteins, it contains a distinct beta-hairpin projection that is absent in these related proteins. This projection is near the site of a well-characterized mutation that reduces the binding of PII and near other less-characterized mutations that affect the phosphatase activity of NRII. Sequence alignment suggests that the beta-hairpin projection is present in NRII proteins from various organisms, and absent in other transmitter proteins from Escherichia coliK-12. This unique structural element in the NRII C-terminal domain may play a role in binding PII or in intramolecular signal transduction. |
| Links |
PubMed Online version:10.1021/bi049474r |
| Keywords |
Adenosine Triphosphate/metabolism; Amino Acid Sequence; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Crystallography, X-Ray; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/genetics; Escherichia coli Proteins/isolation & purification; Escherichia coli Proteins/metabolism; Models, Molecular; Molecular Sequence Data; Mutation; PII Nitrogen Regulatory Proteins; Phosphoprotein Phosphatases/chemistry; Phosphoprotein Phosphatases/genetics; Phosphoprotein Phosphatases/isolation & purification; Phosphoprotein Phosphatases/metabolism; Protein Conformation; Protein Kinases/chemistry; Protein Kinases/genetics; Protein Kinases/isolation & purification; Protein Kinases/metabolism; Protein Structure, Tertiary; Sequence Homology, Amino Acid; Solubility; Structure-Activity Relationship |
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