4aj3

3D structure of E. coli Isocitrate Dehydrogenase in complex with Isocitrate, calcium(II) and NADP - The pseudo-Michaelis complex

spinqualitylabelsall models 4aj3, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4aj3 is a 1 chain structure with sequence from Ecoli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CA, ICT, NAP Related: 4aja, 4ajb, 4ajc, 4ajs, 4ajr Activity: Isocitrate dehydrogenase (NADP(+)), with EC number 1.1.1.42 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed NADP(+) dependent isocitrate dehydrogenase (IDH; EC 1.1.1.42) belongs to a large family of alpha-hydroxyacid oxidative beta-decarboxylases that catalyze similar three-step reactions, with dehydrogenation to an oxaloacid intermediate preceding beta-decarboxylation to an enol intermediate followed by tautomerization to the final alpha-ketone product. A comprehensive view of the induced fit needed for catalysis is revealed on comparing the first "fully closed" crystal structures of a pseudo-Michaelis complex of wild-type Escherichia coli IDH (EcoIDH) and the "fully closed" reaction product complex of the K100M mutant with previously obtained "quasi-closed" and "open" conformations. Conserved catalytic residues, binding the nicotinamide ring of NADP(+) and the metal-bound substrate, move as rigid bodies during domain closure by a hinge motion that spans the central beta-sheet in each monomer. Interactions established between Thr105 and Ser113, which flank the "phosphorylation loop", and the nicotinamide mononucleotide moiety of NADP(+) establish productive coenzyme binding. Electrostatic interactions of a Lys100-Leu103-Asn115-Glu336 tetrad play a pivotal role in assembling a catalytically competent active site. As predicted, Lys230* is positioned to deprotonate/reprotonate the alpha-hydroxyl in both reaction steps and Tyr160 moves into position to protonate C3 following beta-decarboxylation. A proton relay from the catalytic triad Tyr160-Asp307-Lys230* connects the alpha-hydroxyl of isocitrate to the bulk solvent to complete the picture of the catalytic mechanism. Induced fit and the catalytic mechanism of isocitrate dehydrogenase.,Goncalves S, Miller SP, Carrondo MA, Dean AM, Matias PM Biochemistry. 2012 Sep 11;51(36):7098-115. Epub 2012 Aug 27. PMID:22891681 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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