4d8l

Crystal structure of the 2-pyrone-4,6-dicarboxylic acid hydrolase from sphingomonas paucimobilis

spinqualitylabelsall models 4d8l, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4d8l is a 1 chain structure with sequence from Sphingomonas paucimobilis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function LIGI_SPHSK Contributes to the degradation of lignin at the level of the protocatechuate 4,5-cleavage pathway (PubMed:9864312). Catalyzes the hydrolysis of 2-pyrone-4,6-dicarboxylate (PDC) to (4E)-oxalomesaconate (OMA) (PubMed:22475079, PubMed:29658701). The keto form of OMA can tautomerize into the enol form, 4-carboxy-2-hydroxymuconate (CHM), under certain pH conditions (PubMed:22475079). Also catalyzes the reverse reaction (PubMed:22475079, PubMed:9864312). Is essential for the growth of Sphingobium sp. SYK-6 on vanillate but is not responsible for the growth of this strain on syringate (PubMed:9864312). Publication Abstract from PubMed LigI from Sphingomonas paucimobilis catalyzes the reversible hydrolysis of 2-pyrone-4,6-dicarboxylate (PDC) to 4-oxalomesaconate and 4-carboxy-2-hydroxymuconate in the degradation of lignin. This protein is a member of the amidohydrolase superfamily of enzymes. The protein was expressed in Escherichia coli and then purified to homogeneity. The purified recombinant enzyme does not contain bound metal ions, and the addition of metal chelators or divalent metal ions to the assay mixtures does not affect the rate of product formation. This is the first enzyme from the amidohydrolase superfamily that does not require a divalent metal ion for catalytic activity. The kinetic constants for the hydrolysis of PDC are 340 s(-1) and 9.8 x 10(6) M(-1) s(-1) (k(cat) and k(cat)/K(m), respectively). The pH dependence on the kinetic constants suggests that a single active site residue must be deprotonated for the hydrolysis of PDC. The site of nucleophilic attack was determined by conducting the hydrolysis of PDC in (18)O-labeled water and subsequent (13)C nuclear magnetic resonance analysis. The crystal structures of wild-type LigI and the D248A mutant in the presence of the reaction product were determined to a resolution of 1.9 A. The C-8 and C-11 carboxylate groups of PDC are coordinated within the active site via ion pair interactions with Arg-130 and Arg-124, respectively. The hydrolytic water molecule is activated by the transfer of a proton to Asp-248. The carbonyl group of the lactone substrate is activated by electrostatic interactions with His-180, His-31, and His-33. Structure and Catalytic Mechanism of LigI: Insight into the Amidohydrolase Enzymes of cog3618 and Lignin Degradation.,Hobbs ME, Malashkevich V, Williams HJ, Xu C, Sauder JM, Burley SK, Almo SC, Raushel FM Biochemistry. 2012 Apr 9. PMID:22475079 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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