2v5h

Controlling the storage of nitrogen as arginine: the complex of PII and acetylglutamate kinase from Synechococcus elongatus PCC 7942

spinqualitylabelsall models 2v5h, resolution 2.75Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2v5h is a 12 chain structure with sequence from Anacystis nidulans r2. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CL, GOL, NA, NLG Related: 1qy7, 2jj4 Activity: Acetylglutamate kinase, with EC number 2.7.2.8 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [GLNB_SYNE7] P-II indirectly controls the transcription of the GS gene (glnA). P-II prevents NR-II-catalyzed conversion of NR-I to NR-I-phosphate, the transcriptional activator of glnA. When P-II is phosphorylated, these events are reversed. In nitrogen-limiting conditions, when the ratio of Gln to 2-ketoglutarate decreases, P-II is phosphorylated which allows the deadenylation of glutamine synthetase (GS), thus activating the enzyme. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Photosynthetic organisms can store nitrogen by synthesizing arginine, and, therefore, feedback inhibition of arginine synthesis must be relieved in these organisms when nitrogen is abundant. This relief is accomplished by the binding of the PII signal transduction protein to acetylglutamate kinase (NAGK), the controlling enzyme of arginine synthesis. Here, we describe the crystal structure of the complex between NAGK and PII of Synechococcus elongatus, at 2.75-A resolution. We prove the physiological relevance of the observed interactions by site-directed mutagenesis and functional studies. The complex consists of two polar PII trimers sandwiching one ring-like hexameric NAGK (a trimer of dimers) with the threefold axes of these molecules aligned. The binding of PII favors a narrow ring conformation of the NAGK hexamer that is associated with arginine sites having low affinity for this inhibitor. Each PII subunit contacts one NAGK subunit only. The contacts map in the inner circumference of the NAGK ring and involve two surfaces of the PII subunit. One surface is on the PII body and interacts with the C-domain of the NAGK subunit, helping widen the arginine site found on the other side of this domain. The other surface is at the distal region of a protruding large loop (T-loop) that presents a novel compact shape. This loop is inserted in the interdomain crevice of the NAGK subunit, contacting mainly the N-domain, and playing key roles in anchoring PII on NAGK, in activating NAGK, and in complex formation regulation by MgATP, ADP, 2-oxoglutarate, and by phosphorylation of serine-49. The crystal structure of the complex of PII and acetylglutamate kinase reveals how PII controls the storage of nitrogen as arginine.,Llacer JL, Contreras A, Forchhammer K, Marco-Marin C, Gil-Ortiz F, Maldonado R, Fita I, Rubio V Proc Natl Acad Sci U S A. 2007 Nov 6;104(45):17644-9. Epub 2007 Oct 24. PMID:17959776 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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