Human DNA glycosylases of the bacterial Fpg/MutM superfamily:: an alternative pathway for the repair of 8-oxoguanine and other oxidation products in DNA
Human DNA glycosylases of the bacterial Fpg/MutM superfamily:: an alternative pathway for the repair of 8-oxoguanine and other oxidation products in DNA
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DOI：
10.1093/nar/gkf618
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发表时间：
2002-11-15
影响因子：
14.9
通讯作者：
Seeberg, E
中科院分区：
文献类型：
--
作者：
Morland, I;Rolseth, V;Seeberg, E
与小鼠 OGG1 和 NTH1 基因的靶向破坏相关的温和表型归因于去除氧化 DNA 碱基的后备活性和/或替代途径的存在。我们在人类细胞中鉴定了两个编码 DNA 糖基化酶的新基因，与细菌 Fpg (MutM)/Nei 类酶同源，能够去除 hOGG1 和 hNTH1 底物的病变。一种名为 HFPG1 的基因在所有检查的组织中都显示出普遍表达，而第二种基因 HFPG2 仅在胸腺和睾丸中以可检测水平表达。用 cDNA 与 EGFP 融合的 HeLa 细胞瞬时转染显示 hFPG1 细胞内分选到细胞核并在核仁中积累，而 hFPG2 与 RPA 的 30 kDa 亚基共定位。 hFPG1 经纯化并显示可作用于含有 8-氧代鸟嘌呤、5-羟基胞嘧啶和脱碱基位点的 DNA 底物。 8-氧代鸟嘌呤的去除，而不是无碱基位点的裂解，是相反的碱基依赖性，8-oxoG:C 是首选底物，对 8-oxoG:A 的活性可以忽略不计。因此，hFPG1 具有与哺乳动物 OGG1 相似的特性，可以防止因 A 跨 8-oxoG 错误掺入而产生的突变，并且可以在 ogg1(-/-) 小鼠中充当 OGG1 的后备修复活性。
The mild phenotype associated with targeted disruption of the mouse OGG1 and NTH1 genes has been attributed to the existence of back-up activities and/or alternative pathways for the removal of oxidised DNA bases. We have characterised two new genes in human cells that encode DNA glycosylases, homologous to the bacterial Fpg (MutM)/Nei class of enzymes, capable of removing lesions that are substrates for both hOGG1 and hNTH1. One gene, designated HFPG1, showed ubiquitous expression in all tissues examined whereas the second gene, HFPG2, was only expressed at detectable levels in the thymus and testis. Transient transfections of HeLa cells with fusions of the cDNAs to EGFP revealed intracellular sorting to the nucleus with accumulation in the nucleoli for hFPG1, while hFPG2 co-localised with the 30 kDa subunit of RPA. hFPG1 was purified and shown to act on DNA substrates containing 8-oxoguanine, 5-hydroxycytosine and abasic sites. Removal of 8-oxoguanine, but not cleavage at abasic sites, was opposite base-dependent, with 8-oxoG:C being the preferred substrate and negligible activity towards 8-oxoG:A. It thus appears that hFPG1 has properties similar to mammalian OGG1 in preventing mutations arising from misincorporation of A across 8-oxoG and could function as a back-up repair activity for OGG1 in ogg1(-/-) mice.