The hydantoin lesions formed from oxidation of 7,8-dihydro-8-oxoguanine are potent sources of replication errors in vivo
The hydantoin lesions formed from oxidation of 7,8-dihydro-8-oxoguanine are potent sources of replication errors in vivo
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DOI：
10.1021/bi0347252
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发表时间：
2003-08-12
期刊：
影响因子：
2.9
通讯作者：
Essigmann, JM
中科院分区：
文献类型：
--
作者：
Henderson, PT;Delaney, JC;Essigmann, JM
已经构建了单链DNA基因组，其位点特异性地含有7，8-二氢-8-氧代-2 '-脱氧鸟嘌呤（8-oxoG）氧化产物胍基乙内酰脲（Gh）和螺亚氨基二乙内酰脲的两种稳定立体异构体（Sp1和Sp2）。将环状病毒基因组转染到野生型AB 1157大肠杆菌中，并评估DNA聚合酶绕过病变的效率。使用最近开发的限制性内切酶和后标记（REAP）测定分析病毒后代的突变频率和类型。Gh几乎与亲本8-oxoG一样有效地被绕过，但具有高度致突变性，导致几乎排他性的G -> C颠换。相比之下，立体异构体Sp1和Sp2对DNA聚合酶延伸具有更强的阻断作用，并导致G -> T和G -> C颠换的混合物。每个Sp损伤的G -> T与G -> C突变的比例取决于碱基的立体化学构型。所有观察到的突变频率至少比8-oxoG引起的突变频率高一个数量级。如果这些损伤是在体内形成的。我们的数据显示它们绝对是错误编码的，并且在经损伤合成后可能难以修复。
Single-stranded DNA genomes have been constructed that site-specifically contain the 7,8dihydro-8-oxo-2'-deoxyguanine (8-oxoG) oxidation products guanidinohydantoin (Gh) and the two stable stereoisomers of spiroiminodihydantoin (Sp1 and Sp2). The circular viral genomes were transfected into wild-type AB1157 Escherichia coli, and the efficiency of lesion bypass by DNA polymerase(s) was assessed. Viral progeny were analyzed for mutation frequency and type using the recently developed restriction endonuclease and postlabeling (REAP) assay. Gh was bypassed nearly as efficiently as the parent 8-oxoG but was highly mutagenic, causing almost exclusive G --> C transversions. The stereoisomers Sp1 and Sp2 were, in comparison, much stronger blocks to DNA polymerase extension and caused a mixture of G --> T and G --> C transversions. The ratio of G --> T to G --> C mutations for each Sp lesion was dependent on the stereochemical configuration of the base. All observed mutation frequencies were at least an order of magnitude higher than those caused by 8-oxoG. Were these lesions to be formed in vivo. our data show that they are absolutely miscoding and may be refractory to repair after translesion synthesis.