1pkh

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spinqualitylabelsall models 1pkh, resolution 1.42Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

STRUCTURAL BASIS FOR RECOGNITION AND CATALYSIS BY THE BIFUNCTIONAL DCTP DEAMINASE AND DUTPASE FROM METHANOCOCCUS JANNASCHII

Overview

Potentially mutagenic uracil-containing nucleotide intermediates are, generated by deamination of dCTP, either spontaneously or enzymatically as, the first step in the conversion of dCTP to dTTP. dUTPases convert dUTP to, dUMP, thus avoiding the misincorporation of dUTP into DNA and creating the, substrate for the next enzyme in the dTTP synthetic pathway, thymidylate, synthase. Although dCTP deaminase and dUTPase activities are usually found, in separate but homologous enzymes, the hyperthermophile Methanococcus, jannaschii has an enzyme, DCD-DUT, that harbors both dCTP deaminase and, dUTP pyrophosphatase activities. DCD-DUT has highest activity on dCTP, followed by dUTP, and dTTP inhibits both the deaminase and pyrophosphatase, activities. To help clarify structure-function relationships for DCD-DUT, we have determined the crystal structure of the wild-type DCD-DUT protein, in its apo form to 1.42A and structures of DCD-DUT in complex with dCTP, and dUTP to resolutions of 1.77A and 2.10A, respectively. To gain insights, into substrate interactions, we complemented analyses of the, experimentally defined weak density for nucleotides with automated docking, experiments using dCTP, dUTP, and dTTP. DCD-DUT is a hexamer, unlike the, homologous dUTPases, and its subunits contain several insertions and, substitutions different from the dUTPase beta barrel core that likely, contribute to dCTP specificity and deamination. These first structures of, a dCTP deaminase reveal a probable role for an unstructured C-terminal, region different from that of the dUTPases and possible mechanisms for, both bifunctional enzyme activity and feedback inhibition by dTTP.

About this Structure

1PKH is a Single protein structure of sequence from Methanocaldococcus jannaschii with EDO as ligand. Full crystallographic information is available from OCA.

Reference

Structural basis for recognition and catalysis by the bifunctional dCTP deaminase and dUTPase from Methanococcus jannaschii., Huffman JL, Li H, White RH, Tainer JA, J Mol Biol. 2003 Aug 22;331(4):885-96. PMID:12909016

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