The Oxidized Forms of dATP Are Substrates for the Human MutT Homologue, the hMTH1 Protein
| Autor: | Yoshimitsu Fujii, Hiroyuki Kamiya, Hiroshi Kasai, Yusaku Nakabeppu, Katsuyoshi Fujikawa, Hiroyuki Yakushiji |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Stereochemistry
medicine.disease_cause Biochemistry Substrate Specificity chemistry.chemical_compound Hydrolysis Deoxyadenine Nucleotides Bacterial Proteins Escherichia Hydrolase Escherichia coli medicine Humans heterocyclic compounds Nucleotide Pyrophosphatases Molecular Biology Chromatography High Pressure Liquid chemistry.chemical_classification biology Escherichia coli Proteins Cell Biology Hydrogen-Ion Concentration biology.organism_classification Phosphoric Monoester Hydrolases Kinetics enzymes and coenzymes (carbohydrates) DNA Repair Enzymes Enzyme chemistry Oxidation-Reduction DNA |
| Zdroj: | Journal of Biological Chemistry. 274:18201-18205 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.274.26.18201 |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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