Oxygen-induced DNA Damage and its Repair Mechanisms

氧诱导的DNA损伤及其修复机制

• 批准号: 06044177
• 负责人: SEKIGUCHI Mutsuo
• 金额: $ 1.6万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 无数据
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06044177/
• 关键词: Spontaneous Mutation; Mutator; cDNA Cloning; 8-Oxo-dGTP; Oxidative Damage; DNA Replication; DNA Repair

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.

8-氧代-dGTP(8-氧-7，8-二氢脱氧鸟苷三磷酸)是DNA合成的有效诱变底物。8-oxo-dGTP在核苷酸池中的积累导致G：C到T：A颠倒和A：T到C：G颠倒，而大肠杆菌细胞具有防止这种突变的机制。通过分析缺乏8-oxo-dGTP酶(Mutt蛋白)和/或抑制DNA中8-oxo-GTP引起的突变的修复酶(MutM和MutY蛋白)，这些蛋白质在控制自发突变中的协同作用变得明显。在缺乏Mutt和/或MutM蛋白的突变菌株中，DNA的8-oxo-duanine浓度增加到预期的突变速度。人类细胞具有将8-oxo-dGTP水解成8-oxo-dGMP的酶活性，从而防止误掺入引起的突变的发生。当人8-oxo-dGTP酶基因在自身8-oxo-dGTP酶活性缺失的突变细胞中表达时，自发A：T到C：G突变频率的升高恢复到正常水平。我们分离了编码该酶的基因组序列，并将该基因命名为MTH1(MUT人类同源基因)。该基因至少由4个外显子组成，全长约9kb，位于人类染色体7p22上。

项目成果

T.Ishibashi: "Intracellular localization of DNA repair methyltransferase in human cells" Mutation Res.315. 199-212 (1994)

T.Ishibashi：“人类细胞中 DNA 修复甲基转移酶的细胞内定位”Mutation Res.315。

T.Tajiri: "Functional cooperation of MutT,MutM and MutY proteins in preventing mutations" Mutation Res.336. 245-255 (1995)

T.Tajiri：“MutT、MutM 和 MutY 蛋白在预防突变方面的功能合作”Mutation Res.336。

S.Oda: "ΔFosB-mediated stabilization of cyclin E and CdK2mRNAs at the G1-S transition" Oncogene. 10. 1343-1351 (1995)

S.Oda：“ΔFosB 介导的细胞周期蛋白 E 和 CdK2mRNA 在 G1-S 转变时的稳定性”Oncogene，10. 1343-1351 (1995)。

T.Ishibashi: "Artificial control of nuclear translocation of DNA repair methyltransferase" J.Biol.Chem.269. 7645-7650 (1994)

T.Ishibashi：“DNA 修复甲基转移酶核转位的人工控制”J.Biol.Chem.269。

T.Ohkubo: "Methylation dependent functional switch mechanism newly found in the E.coli Ada protein" J.Am.Chem.Soc.116. 6035-6036 (1994)

T.Ohkubo：“在大肠杆菌 Ada 蛋白中新发现的甲基化依赖性功能开关机制”J.Am.Chem.Soc.116。