2rd5

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spinqualitylabelsall models 2rd5, resolution 2.51Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Structural basis for the regulation of N-acetylglutamate kinase by PII in Arabidopsis thaliana

Overview

PII is a highly conserved regulatory protein found in organisms across the, three domains of life. In cyanobacteria and plants, PII relieves the, feedback inhibition of the rate-limiting step in arginine biosynthesis, catalyzed by N-acetylglutamate kinase (NAGK). To understand the molecular, structural basis of enzyme regulation by PII, we have determined a 2.5-A, resolution crystal structure of a complex formed between two homotrimers, of PII and a single hexamer of NAGK from Arabidopsis thaliana bound to the, metabolites N-acetylglutamate, ADP, ATP, and arginine. In PII, the T-loop, and Trp(22) at the start of the alpha1-helix, which are both adjacent to, the ATP-binding site of PII, contact two beta-strands as well as the ends, of two central helices (alphaE and alphaG) in NAGK, the opposing ends of, which form major portions of the ATP and N-acetylglutamate, substrate-binding sites. The binding of Mg(2+).ATP to PII stabilizes a, conformation of the T-loop that favors interactions with both open and, closed conformations of NAGK. Interactions between PII and NAGK appear to, limit the degree of opening and closing of the active-site cleft in, opposition to a domain-separating inhibitory effect exerted by arginine, thus explaining the stimulatory effect of PII on the kinetics of, arginine-inhibited NAGK.

About this Structure

2RD5 is a Protein complex structure of sequences from Arabidopsis thaliana with , , , and as ligands. Active as Acetylglutamate kinase, with EC number 2.7.2.8 Full crystallographic information is available from OCA.

Reference

Structural Basis for the Regulation of N-Acetylglutamate Kinase by PII in Arabidopsis thaliana., Mizuno Y, Moorhead GB, Ng KK, J Biol Chem. 2007 Dec 7;282(49):35733-40. Epub 2007 Oct 3. PMID:17913711

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