Processing of a complex multiply damaged DNA site by human cell extracts and purified repair proteins.
Processing of a complex multiply damaged DNA site by human cell extracts and purified repair proteins.
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DOI：
10.1093/nar/gki165
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发表时间：
2005
影响因子：
14.9
通讯作者：
Sage E
中科院分区：
文献类型：
--
作者：
Eot-Houllier G;Eon-Marchais S;Gasparutto D;Sage E
可能由电离辐射引起的DNA损伤，构成了修复过程的试验。事实上，最近的研究表明，这种病变的修复可能会受到损害，可能导致形成致命的双链断裂（DSB）。构建了由8-氧代鸟嘌呤和8-氧代腺嘌呤、5-羟基尿嘧啶、5-甲酰尿嘧啶和1 nt缺口组成的复合多重损伤位点（MDS），长度在17 bp以内，并用于人全细胞提取物和纯化的修复酶对BER途径的几个步骤进行攻击。我们显示了一个层次内的MDS病变的处理，特别是在基础切除步骤。在本发明的构型中，5-羟基尿嘧啶的有效切除和8-氧代鸟嘌呤的低切割防止DSB形成并产生携带8-氧代鸟嘌呤的短单链区域。另一方面，重新加入的1 nt的差距发生的短补丁BER途径，但略有延迟的氧化碱的存在下。两者合计，我们的研究结果表明，在MDS内的病变，这可以防止DSB的形成，但会显着提高诱变处理的层次。它们还表明，复杂MDS的致突变（或致死）后果将在很大程度上取决于MDS处理中的第一个事件。
Clustered DNA lesions, possibly induced by ionizing radiation, constitute a trial for repair processes. Indeed, recent studies suggest that repair of such lesions may be compromised, potentially leading to the formation of lethal double-strand breaks (DSBs). A complex multiply damaged site (MDS) composed of 8-oxoguanine and 8-oxoadenine on one strand, 5-hydroxyuracil, 5-formyluracil and a 1 nt gap on the other strand, within 17 bp was built and used to challenge several steps of base excision repair (BER) pathway with human whole-cell extracts and purified repair enzymes as well. We show a hierarchy in the processing of lesions within the MDS, in particular at the base excision step. In the present configuration, efficient excision of 5-hydroxyuracil and low cleavage at 8-oxoguanine prevent DSB formation and generate a short single-stranded region carrying the 8-oxoguanine. On the other hand, rejoining of the 1 nt gap occurs by the short-patch BER pathway, but is slightly retarded by the presence of the oxidized bases. Taken together, our results suggest a hierarchy in the processing of the lesions within the MDS, which prevents the formation of DSB, but would dramatically enhance mutagenesis. They also indicate that the mutagenic (or lethal) consequences of a complex MDS will largely depend on the first event in the processing of the MDS.