Identification of the dITP- and XTP-hydrolyzing protein from Escherichia coli

J Biochem Mol Biol. 2002 Jul 31;35(4):403-8. doi: 10.5483/bmbrep.2002.35.4.403.


A hypothetical 21.0 kDa protein (ORF O197) from Escherichia coli K-12 was cloned, purified, and characterized. The protein sequence of ORF O197 (termed EcO197) shares a 33.5% identity with that of a novel NTPase from Methanococcus jannaschii. The EcO197 protein was purified using Ni-NTA affinity chromatography, protease digestion, and gel filtration column. It hydrolyzed nucleoside triphosphates with an O6 atom-containing purine base to nucleoside monophosphate and pyrophosphate. The EcO197 protein had a strong preference for deoxyinosine triphosphate (dITP) and xanthosine triphosphate (XTP), while it had little activity in the standard nucleoside triphosphates (dATP, dCTP, dGTP, and dTTP). These aberrant nucleotides can be produced by oxidative deamination from purine nucleotides in cells; they are potentially mutagenic. The mutation protection mechanisms are caused by the incorporation into DNA of unwelcome nucleotides that are formed spontaneously. The EcO197 protein may function to eliminate specifically damaged purine nucleotide that contains the 6-keto group. This protein appears to be the first eubacterial dITP- and XTPhydrolyzing enzyme that has been identified.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acid Anhydride Hydrolases / genetics
  • Amino Acid Sequence
  • Base Sequence
  • Cloning, Molecular
  • DNA, Bacterial / genetics
  • Escherichia coli / genetics
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / isolation & purification
  • Escherichia coli Proteins / metabolism*
  • Hydrolysis
  • Inosine Triphosphate / analogs & derivatives*
  • Inosine Triphosphate / metabolism*
  • Methanococcus / enzymology
  • Methanococcus / genetics
  • Molecular Sequence Data
  • Nucleoside-Triphosphatase
  • Ribonucleotides / metabolism*
  • Sequence Homology, Amino Acid


  • DNA, Bacterial
  • Escherichia coli Proteins
  • Ribonucleotides
  • Inosine Triphosphate
  • 2'-deoxyinosine triphosphate
  • xanthosine 5'-triphosphate
  • Acid Anhydride Hydrolases
  • Nucleoside-Triphosphatase