2jj4

From Proteopedia

Revision as of 10:02, 23 January 2008

THE COMPLEX OF PII AND ACETYLGLUTAMATE KINASE FROM SYNECHOCOCCUS ELONGATUS PCC7942

Overview

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 P(II) 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 P(II) 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 P(II) trimers, sandwiching one ring-like hexameric NAGK (a trimer of dimers) with the, threefold axes of these molecules aligned. The binding of P(II) favors a, narrow ring conformation of the NAGK hexamer that is associated with, arginine sites having low affinity for this inhibitor. Each P(II) subunit, contacts one NAGK subunit only. The contacts map in the inner, circumference of the NAGK ring and involve two surfaces of the P(II), subunit. One surface is on the P(II) 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 P(II), on NAGK, in activating NAGK, and in complex formation regulation by MgATP, ADP, 2-oxoglutarate, and by phosphorylation of serine-49.

About this Structure

2JJ4 is a Protein complex structure of sequences from Synechococcus elongatus with as ligand. Active as Acetylglutamate kinase, with EC number 2.7.2.8 Known structural/functional Sites: and . Full crystallographic information is available from OCA.

Reference

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

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