The substrate specificity of MutY for hyperoxidized guanine lesions in vivo
The substrate specificity of MutY for hyperoxidized guanine lesions in vivo
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DOI：
10.1021/bi061174h
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发表时间：
2007-02-06
期刊：
影响因子：
2.9
通讯作者：
Essigmann, John M.
中科院分区：
文献类型：
--
作者：
Delaney, Sarah;Neeley, William L.;Essigmann, John M.
DNA损伤产物7，8-二氢-8-氧代-2 '-脱氧鸟嘌呤（8-oxoG）是氧化应激的常用生物标志物。这种DNA损伤的致突变潜力在大肠杆菌中被多种酶减轻。其中一种酶MutY切除与8-oxoG错配的A，作为恢复原始G：C碱基对过程的一部分。然而，许多研究表明，8-oxoG在化学上对进一步氧化不稳定。在这里，我们研究了MutY对8-oxoG氧化产物胍基乙内酰脲（Gh）、螺亚氨基二乙内酰脲（Sp1和Sp2）的两种非对映异构体、尿酸（Oa）和尿素（Ur）的活性。构建了含有位点特异性损伤的单链病毒基因组，并在E.这些大肠杆菌要么擅长DNA修复，要么缺乏MutY。这些病变以前被发现是潜在的致突变性修复能力的细菌，我们在这里报告说，这些8-oxoG衍生的病变同样错误编码时，在E。缺乏MutY的大肠杆菌;未观察到突变身份或频率的显著变化。然而，有趣的是，在MutY存在的情况下，Sp1和Sp2比缺乏这种修复酶的细胞更具毒性。
The DNA damage product 7,8-dihydro-8-oxo-2'-deoxyguanine (8-oxoG) is a commonly used biomarker of oxidative stress. The mutagenic potential of this DNA lesion is mitigated in Escherichia coli by multiple enzymes. One of these enzymes, MutY, excises an A mispaired with 8-oxoG as part of the process to restore the original G:C base pair. However, numerous studies have shown that 8-oxoG is chemically labile toward further oxidation. Here, we examine the activity of MutY on the 8-oxoG oxidation products guanidinohydantoin (Gh), two diastereomers of spiroiminodihydantoin (Sp1 and Sp2), oxaluric acid (Oa), and urea (Ur). Single-stranded viral genomes containing a site-specific lesion were constructed and replicated in E. coli that are either proficient in DNA repair or that lack MutY. These lesions were found previously to be potently mutagenic in repair competent bacteria, and we report here that these 8-oxoG-derived lesions are equally miscoding when replicated in E. coli lacking MutY; no significant change in mutation identity or frequency is observed. Interestingly, however, in the presence of MutY, Sp1 and Sp2 are more toxic than in cells lacking this repair enzyme.