Efficiency of incision of an AP site within clustered DNA damage by the major human AP endonuclease
Efficiency of incision of an AP site within clustered DNA damage by the major human AP endonuclease
复制标题
DOI：
10.1021/bi011682l
复制
发表时间：
2002-01-15
期刊：
影响因子：
2.9
通讯作者：
O'Neill, P
中科院分区：
文献类型：
--
作者：
David-Cordonnier, MH;Cunniffe, SMT;O'Neill, P
一种主要的DNA损伤是由电离辐射引起的，由各种糖基酶清除氧化碱基损伤而形成的，即无嘌呤/脱嘧啶位点(AP位点)。如果主要的人类AP内切酶HAP1不能有效地切割AP位点，那么暴露于电离辐射或拟放射抗癌剂后引起的簇状DNA损伤中AP位点的存在可能会对细胞的修复机制构成挑战。在这项研究中，含有位于互补链上与另一种损伤[5，6-二氢胸腺嘧啶(DHT)、8-oxoG、AP位点或各种类型的单链断裂]相对位置的AP位点的特定寡核苷酸结构被用来确定纯化的HAP1蛋白在切割聚集DNA损伤的AP位点(S)方面的相对效率。相反链上的碱基损伤(DHT和8-oxoG)对HAP1切割AP位点的速率影响很小或没有影响。相反，当位于与AP位点相反的碱基3‘处的一个或三个碱基时，第二个AP位点或各种类型的单链断裂的存在对AP位点的切割效率具有强烈的抑制作用。如果单链断裂(SSB)位于与互补链上AP位点相反的位置的一个或三个碱基3‘，则HAP1与AP位点结合的效率降低类似于1个数量级。如果AP位置和SSB或第二AP位置相对于彼此位于任何其他位置，则可能导致双链断裂。
A major DNA lesion induced by ionizing radiation and formed on removal of oxidized base lesions by various glycosylases is an apurinic/apyrimidinic site (AP site). The presence of an AP site within clustered DNA damage, induced following exposure to ionizing radiation or radiomimetic anticancer agents, may present a challenge to the repair machinery of the cell, if the major human AP endonuclease, HAP1, does not efficiently incise the AP site. In this study, specific oligonucleotide constructs containing an AP site located at several positions opposite to another damage [5,6-dihydrothymine (DHT), 8-oxoG, AP site, or various types of single strand breaks] on the complementary strand were used to determine the relative efficiency of the purified HAP1 protein in incising an AP site(s) from clustered DNA damage. A base damage (DHT and 8-oxoG) on the opposite strand has little or no influence on the rate of incision of an AP site by HAP1. In contrast, the presence of either a second AP site or various types of single strand breaks, when located one or three bases 3' to the base opposite to the AP site, has a strong inhibitory effect on the efficiency of incision of an AP site. The efficiency of binding of HAP1 to an AP site is reduced by similar to1 order of magnitude if a single strand break (SSB) is located one or three bases 3' to the site opposite to the AP site on the complementary strand. If the AP site and either a SSB or a second AP site are located at any of the other positions relative to each other, a double strand break may result.