Dual hydrolysis of diphosphate and triphosphate derivatives of oxidized deoxyadenosine by Orf17 (NtpA), a MutT-type enzyme |
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Authors: | Hori Mika Fujikawa Katsuyoshi Kasai Hiroshi Harashima Hideyoshi Kamiya Hiroyuki |
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Affiliation: | Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812, Japan. |
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Abstract: | To determine whether the Orf17 (NtpA) protein of Escherichia coli, a MutT-type enzyme, functions as a hydrolyzing enzyme for a damaged deoxyribonucleotide, we purified the recombinant Orf17 protein and incubated it with oxidized deoxyribonucleotides. Of the deoxyribonucleoside 5'-triphosphates tested, 8-hydroxy-2'-deoxyadenosine 5'-triphosphate was hydrolyzed by this protein. Unexpectedly, the Orf17 protein degraded 8-hydroxy-2'-deoxyadenosine 5'-diphosphate 2.3-fold more efficiently than the corresponding triphosphate. Thus, this protein is the first MutT-type enzyme that hydrolyzes both the triphosphate and diphosphate derivatives of a deoxyribonucleoside, with similar efficiencies. These results suggest that the Orf17 protein may be involved in the hydrolysis of oxidized dATP and dADP. |
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