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J Biol Chem. 2004 Oct 8;279(41):42907-15. Epub 2004 Jun 17.

Structural insights into the catalytic mechanism of phosphate ester hydrolysis by dUTPase.

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  • 1Institute of Enzymology, Biological Research Center, Hungarian Academy of Science, Budapest, Karolina út 29-31, H-1113, Hungary.

Abstract

dUTPase is essential to keep uracil out of DNA. Crystal structures of substrate (dUTP and alpha,beta-imino-dUTP) and product complexes of wild type and mutant dUTPases were determined to reveal how an enzyme responsible for DNA integrity functions. A kinetic analysis of wild type and mutant dUTPases was performed to obtain relevant mechanistic information in solution. Substrate hydrolysis is shown to be initiated via in-line nucleophile attack of a water molecule oriented by an activating conserved aspartate residue. Substrate binding in a catalytically competent conformation is achieved by (i) multiple interactions of the triphosphate moiety with catalysis-assisting Mg2+, (ii) a concerted motion of residues from three conserved enzyme motifs as compared with the apoenzyme, and (iii) an intricate hydrogen-bonding network that includes several water molecules in the active site. Results provide an understanding for the catalytic role of conserved residues in dUTPases.

PMID:
15208312
[PubMed - indexed for MEDLINE]
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