2rd5
From Proteopedia
Structural basis for the regulation of N-acetylglutamate kinase by PII in Arabidopsis thaliana
Structural highlights
Function[NAGK_ARATH] Involved in the arginine biosynthetic pathway via the intermediate compound ornithine.[1] [2] [GLNB_ARATH] Participates in sensing carbon and organic nitrogen status and regulates some steps of primary carbon and nitrogen metabolism. Required for nitrite uptake in chloroplasts and regulates arginine biosynthesis through interaction with acetylglutamate kinase (NAGK) in chloroplasts. Regulates fatty acids synthesis in chloroplasts by interacting with the acetyl-CoA carboxylase complex and inhibiting acetyl-CoA carboxylase (ACCase) activity.[3] [4] [5] 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 PubMedPII 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. 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[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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