3noj

The structure of HMG/CHA aldolase from the protocatechuate degradation pathway of Pseudomonas putida

spinqualitylabelsall models 3noj, resolution 1.82Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3noj is a 1 chain structure with sequence from Psep1. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: MG, PG4, PYR Gene: pput1361, Pput_1361 (PSEP1) Activity: 4-hydroxy-4-methyl-2-oxoglutarate aldolase, with EC number 4.1.3.17 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [HMGA_PSEP1] Catalyzes the last step of the bacterial protocatechuate 4,5-cleavage pathway. The preferred substrates of the enzyme are 2-keto-4-hydroxy acids with a 4-carboxylate substitution. Catalyzes the conversion of 4-hydroxy-4-methyl-2-oxoglutarate (HMG) to pyruvate. Also catalyzes the conversion of 4-carboxy-4-hydroxy-2-oxoadipic acid (CHA) to pyruvate and oxaloacetate. 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 PubMed HMG/CHA aldolase from Pseudomonas putida F1 catalyzes the last step of the bacterial protocatechuate 4,5- cleavage pathway. The enzyme's preferred substrates are 2-keto-4-hydroxy acids with a 4-carboxylate substitution. The enzyme also exhibits oxaloacetate decarboxylation and pyruvate alpha-proton exchange activity. Sodium oxalate is a competitive inhibitor of the aldolase reaction. The pH dependence of kcat/Km and kcat for the enzyme is consistent with a single deprotonation with pKa values of 8.0 +/- 0.1 and 7.0 +/- 0.1 for free enzyme and enzyme substrate complex, respectively. The 1.8 A x-ray structure shows a four-layered alpha-beta-beta-alpha sandwich structure with the active site at the interface of two adjacent subunits of a hexamer; this fold resembles the RNAse E inhibitor, RraA, but is novel for an aldolase. The catalytic site contains a magnesium ion ligated by Asp124 as well as three water molecules bound by Asp102 and Glu199. A pyruvate molecule binds the magnesium ion through both carboxylate and keto oxygen atoms, completing the octahedral geometry. The carbonyl oxygen also forms a hydrogen bonds with the guanadinium group of Arg123, which site-directed mutagenesis confirms is essential for catalysis. A mechanism for HMG/CHA aldolase is proposed on the basis of the structure, kinetics, and previously established features of other aldolase mechanisms. Structural and kinetic characterization of 4-hydroxy-4-methyl-2-oxoglutarate (HMG)/4-carboxy-4-hydroxy-2-oxoadipate (CHA) aldolase: a protocatechuate degradation enzyme evolutionarily convergent with the HpaI and DmpG pyruvate aldolases.,Wang W, Mazurkewich S, Kimber MS, Seah SY J Biol Chem. 2010 Sep 15. PMID:20843800 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Aldolase

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