The oxidized forms of dATP are substrates for the human MutT homologue, the hMTH1 protein

Katsuyoshi Fujikawa, Hiroyuki Kamiya, Hiroyuki Yakushiji, Yoshimitsu Fujii, Yusaku Nakabeppu, Hiroshi Kasai

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The possibility that Escherichia coli Mutt and human MTH1 (hMTH1) hydrolyze oxidized DNA precursors other than 8-hydroxy-dGTP (8-OH-dGTP) was investigated. We report here that hMTH1 hydrolyzed 2-hydroxy-dATP (2-OH- dATP) and 8-hydroxy-dATP (8-OH-dATP), oxidized forms of dATP, but not (R)- 8,5'-cyclo-dATP, 5-hydroxy-dCTP, and 5-formyl-dUTP. The kinetic parameters indicated that 2-OH-dATP was hydrolyzed more efficiently and with higher affinity than 8-OH-dGTP. 8-OH-dATP was hydrolyzed as efficiently as 8-OH- dGTP. The preferential hydrolysis of 2-OH-dATP over 8-OH-dGTP was observed at all of the pH values tested (pH 7.2 to pH 8.8). In particular, a 5-fold difference in the hydrolysis efficiencies for 2-OH-dATP over 8-OH-dGTP was found at pH 7.2. However, E. coli MutT had no hydrolysis activity for either 2-OH-dATP or 8-OH-dATP. Thus, E. coli MutT is an imperfect counterpart for hMTH1. Furthermore, we found that 2-hydroxy-dADP and 8-hydroxy-dGDP competitively inhibited both the 2-OH-dATP hydrolase and 8-OH-dGTP hydrolase activities of hMTH1. The inhibitory effects of 2-hydroxy-dADP were 3-fold stronger than those of 8-hydroxy-dGDP. These results suggest that the three damaged nucleotides share the same recognition site of hMTH1 and that it is a more important sanitization enzyme than expected thus far.

元の言語英語
ページ(範囲)18201-18205
ページ数5
ジャーナルJournal of Biological Chemistry
274
発行部数26
DOI
出版物ステータス出版済み - 6 25 1999

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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