2004 Fiscal Year Final Research Report Summary
Mutagenesis and repair mechanism of DNA base lesions induced by nitrogen oxides
| Project/Area Number |
15510054
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Risk sciences of radiation/Chemicals
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| Research Institution | HIROSHIMA UNIVERSITY |
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Principal Investigator |
TERATO Hiroaki Hiroshima University, Graduate School of Science, Research Associate, 大学院・理学研究科, 助手 (00243543)
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| Project Period (FY) |
2003 – 2004
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| Keywords | nitrogen oxides / deamination / base damage / crosslink / DNA replication / base pairing / base excision repair(BER) / nucleotide excision repair(NER) |
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| Research Abstract |
(1)Mutagenesis of deamination products derived from guanine induced by nitrogen oxide
I investigated activities of Escherichia coli DNA polymerase I Klenow fragmen (Pol I Kf)for xanthin (Xan), oxanin (Oxa) and its crosslink-product(Oxa-Sp with spermine for their mutagenesis abilities. The relative activities of translesional elongation of Pol I Kf were for G(1)>Oxa (0.19)>Xan (0.12)>AP site (0.088)>Oxa-Sp(0.035). For insertion abilities of Pol I Kf, Xan in template preferred TM (16% and dGM (14% than other nucleotides, and Oxa in template preferred TMP(49%)than other nucleotides. On the other hand, Oxa-Sp highly inhibited DNA polymerization of the enzyme. These results indicate that their lesions show severe mutagenic properties with respective manner.
(2)Repair activities for Oxa and its crosslink-lesion
I investigated repair activities for Oxa and its crosslink-lesion using purified enzymes and defined oligonucleotide substrates containing these lesions. Firstly, I investigated any DNA glycosylases for these lesions. However, all enzymes I tried showed poor activities to remove these lesions from DNA. The result indicates that base excision repair(BER)is not effective to these lesions. Then, I tied UvrABC complex derived from Bacillus cardotenax for these lesions. The enzyme of nucleotide excision repair(NER)showed nicking activity for DNA substrate containing Oxa-Sp. The nuclear extracts of HeLa cells also showed simlar NER activity for the substrate. These results indicate that Oxa easily converts secondary crosslink lesions such as Oxa-Sp in vivo, and the crosslink lesions can be removed by NER process.
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