4bvt

Cyanuric acid hydrolase: evolutionary innovation by structural concatenation

spinqualitylabelsall models 4bvt, resolution 3.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4bvt is a 2 chain structure with sequence from Pseudomonas sp. ADP. This structure supersedes the now removed PDB entry 3zgu. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 3.1Å Ligands: BR8, MG, PEG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function CAH_PSESD Responsible for the hydrolysis of cyanuric acid, an intermediate formed during catabolism of s-triazine based compounds in herbicides such as atrazine and polymers such as melamine. Catalyzes the hydrolytic opening of the s-triazine ring of cyanuric acid (2,4,6-trihydroxy-s-triazine) to yield carbon dioxide and carboxybiuret, which spontaneously decarboxylates to biuret.[HAMAP-Rule:MF_01989] Publication Abstract from PubMed The cyanuric acid hydrolase, AtzD, is the founding member of a newly identified family of ring-opening amidases. We report the first X-ray structure for this family, which is a novel fold (termed the 'Toblerone' fold) that likely evolved via the concatenation of monomers of the trimeric YjgF superfamily and the acquisition of a metal binding site. Structures of AtzD with bound substrate (cyanuric acid) and inhibitors (phosphate, barbituric acid and melamine), along with mutagenesis studies, allowed the identification of the active site. The AtzD monomer, active site and substrate all possess threefold rotational symmetry, to the extent that the active site possesses three potential Ser-Lys catalytic dyads. A single catalytic dyad (Ser85-Lys42) is hypothesized, based on biochemical evidence and crystallographic data. A plausible catalytic mechanism based on these observations is also presented. A comparison with a homology model of the related barbiturase, Bar, was used to infer the active-site residues responsible for substrate specificity, and the phylogeny of the 68 AtzD-like enzymes in the database were analysed in light of this structure-function relationship. Cyanuric acid hydrolase: evolutionary innovation by structural concatenation.,Peat TS, Balotra S, Wilding M, French NG, Briggs LJ, Panjikar S, Cowieson N, Newman J, Scott C Mol Microbiol. 2013 Jun;88(6):1149-63. doi: 10.1111/mmi.12249. Epub 2013 May 20. PMID:23651355 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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