'''Crystal structure of the C-terminal Domain of the Two-Component System Transmitter Protein NRII (NtrB)'''
===Crystal structure of the C-terminal Domain of the Two-Component System Transmitter Protein NRII (NtrB)===
==Overview==
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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.
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==About this Structure==
==About this Structure==
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[[Category: Pii]]
[[Category: Pii]]
[[Category: Two component system]]
[[Category: Two component system]]
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Revision as of 19:57, 28 July 2008
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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., Song Y, Peisach D, Pioszak AA, Xu Z, Ninfa AJ, Biochemistry. 2004 Jun 1;43(21):6670-8. PMID:15157101
