2v9x

E138D variant of Escherichia coli dCTP deaminase in complex with dUTP

spinqualitylabelsall models 2v9x, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2v9x is a 12 chain structure with sequence from "bacillus_coli"_migula_1895 "bacillus coli" migula 1895. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: DUT, MG, SO4 Related: 1xs1, 1xs4, 1xs6, 2j4h, 2j4q Activity: dCTP deaminase, with EC number 3.5.4.13 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT 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 In Escherichia coli and Salmonella typhimurium about 80% of the dUMP used for dTMP synthesis is derived from deamination of dCTP. The dCTP deaminase produces dUTP that subsequently is hydrolyzed by dUTPase to dUMP and diphosphate. The dCTP deaminase is regulated by dTTP that inhibits the enzyme by binding to the active site and induces an inactive conformation of the trimeric enzyme. We have analyzed the role of residues previously suggested to play a role in catalysis. The mutant enzymes R115Q, S111C, S111T and E138D were all purified and analyzed for activity. Only S111T and E138D displayed detectable activity with a 30- and 140-fold reduction in k(cat), respectively. Furthermore, S111T and E138D both showed altered dTTP inhibition compared to wild-type enzyme. S111T was almost insensitive to the presence of dTTP. With the E138D enzyme the dTTP dependent increase in cooperativity of dCTP saturation was absent, although the dTTP inhibition itself was still cooperative. Modeling of the active site of the S111T enzyme indicated that this enzyme is restricted in forming the inactive dTTP binding conformer due to steric hindrance by the additional methyl group in threonine. The crystal structure of E138D in complex with dUTP showed a hydrogen bonding network in the active site similar to wild-type enzyme. However, changes in the hydrogen bond lengths between the carboxylate and a catalytic water molecule as well as a slightly different orientation of the pyrimidine ring of the bound nucleotide may provide an explanation for the reduced activity. Mutational analysis of the nucleotide binding site of Escherichia coli dCTP deaminase.,Thymark M, Johansson E, Larsen S, Willemoes M Arch Biochem Biophys. 2008 Feb 1;470(1):20-6. Epub 2007 Oct 30. PMID:17996716 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Deaminase 3D structures

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