| Project/Area Number |
06044177
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
SEKIGUCHI Mutsuo Medical Institute of Bioregulation, Kyushu University, Professor, 生体防御医学研究所, 教授 (00037342)
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| Co-Investigator(Kenkyū-buntansha) |
NUNOSHIDA Tatsuo Faculty of Science, Tohoku University, Research Associate, 理学部, 助手
BRUCE Demple ハーバード大学, 公衆衛生学部, 教授
NAKABEPPU Yusaku Medical Institute of Bioregulation, Kyushu University, Research Associate, 生体防御医学研究所, 助手 (30180350)
TSUZUKI Teruhisa Medical Institute of Bioregulation, Kyushu University, Associate Professor, 生体防御医学研究所, 助教授 (40155429)
DEMPLE Bruce School of Public Health, Harvard University, Professor
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| Project Period (FY) |
1994
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| Project Status |
Completed (Fiscal Year 1994)
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| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1994: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Keywords | Spontaneous Mutation / Mutator / cDNA Cloning / 8-Oxo-dGTP / Oxidative Damage / DNA Replication / DNA Repair |
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| Research Abstract |
8-Oxo-dGTP (8-oxo-7,8-dihydrodeoxyguanosine triphosphate) is a potent mutagenic substrate for DNA synthesis. The accumulation of 8-oxo-dGTP in the nucleotide pool induces G : C to T : A transversion as well as A : T to C : G transversion, and Escherichia coli cells possess mechanisms for preventing such mutations. The mutT gene product specifically hydrolyzes 8-oxo-dGTP to the monophosphate form while the mutM and the mutY gene products function to correct misincorporation of 8-oxo-guanine into DNA.From analyzes odf forward mutations incuced in cells lacking 8-oxo-dGTPase (MutT protein) and/or repair enzymes that suppress mutations caused by 8-oxo-guanine in DNA (MutM and MutY proteins), cooperative functions of these proteins in control of the spontqneous mutagenesis became evident. In mutator strains lacking MutT and/or MutM proteins, 8-oxo-duanine of DNA increased to a concentration expected from the increased rate of mutaion.
Human cells contain enzyme activity that hydrolyzes 8-oxo-dGTP to 8-oxo-dGMP,therby preventing occurence of mutations, caused by misincorporation. When the cDNA for human 8-oxo-dGTPase was expressed in E.coli mutT^- mutant cells devoid of self 8-oxo-dGTPase activity, the elevated level of spontaneous A : T to C : G mutastion frequency reverted to normal. We isolated the genomic sequence encoding the enzyme and named the gene MTH1 (for mutT human homologue). This gene is composed of at least 4 exons, spans approximately 9 kb, and is located on human chromosome 7p22.
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