2g5c
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(New page: 200px<br /><applet load="2g5c" size="350" color="white" frame="true" align="right" spinBox="true" caption="2g5c, resolution 1.90Å" /> '''Crystal Structure of...)
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Revision as of 17:52, 29 January 2008
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Crystal Structure of Prephenate Dehydrogenase from Aquifex aeolicus
Overview
The enzyme prephenate dehydrogenase catalyzes the oxidative, decarboxylation of prephenate to 4-hydroxyphenylpyruvate for the, biosynthesis of tyrosine. Prephenate dehydrogenases exist as either, monofunctional or bifunctional enzymes. The bifunctional enzymes are, diverse, since the prephenate dehydrogenase domain is associated with, other enzymes, such as chorismate mutase and 3-phosphoskimate, 1-carboxyvinyltransferase. We report the first crystal structure of a, monofunctional prephenate dehydrogenase enzyme from the hyper-thermophile, Aquifex aeolicus in complex with NAD+. This protein consists of two, structural domains, a modified nucleotide-binding domain and a novel, helical prephenate binding domain. The active site of prephenate, dehydrogenase is formed at the domain interface and is shared between the, subunits of the dimer. We infer from the structure that access to the, active site is regulated via a gated mechanism, which is modulated by an, ionic network involving a conserved arginine, Arg250. In addition, the, crystal structure reveals for the first time the positions of a number of, key catalytic residues and the identity of other active site residues that, may participate in the reaction mechanism; these residues include Ser126, and Lys246 and the catalytic histidine, His147. Analysis of the structure, further reveals that two secondary structure elements, beta3 and beta7, are missing in the prephenate dehydrogenase domain of the bifunctional, chorismate mutase-prephenate dehydrogenase enzymes. This observation, suggests that the two functional domains of chorismate mutase-prephenate, dehydrogenase are interdependent and explains why these domains cannot be, separated.
About this Structure
2G5C is a Single protein structure of sequence from Aquifex aeolicus vf5 with as ligand. Active as Prephenate dehydrogenase, with EC number 1.3.1.12 Full crystallographic information is available from OCA.
Reference
Crystal structure of prephenate dehydrogenase from Aquifex aeolicus. Insights into the catalytic mechanism., Sun W, Singh S, Zhang R, Turnbull JL, Christendat D, J Biol Chem. 2006 May 5;281(18):12919-28. Epub 2006 Mar 2. PMID:16513644
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