Characterization of abasic endonuclease activity of human Ape1 on alternative substrates, as well as effects of ATP and sequence context on AP site incision
Characterization of abasic endonuclease activity of human Ape1 on alternative substrates, as well as effects of ATP and sequence context on AP site incision
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DOI：
10.1016/j.jmb.2008.03.053
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发表时间：
2008-05-23
影响因子：
5.6
通讯作者：
Wilson, David M., III
中科院分区：
文献类型：
--
作者：
Berquist, Brian R.;McNeill, Daniel R.;Wilson, David M., III
人类Ape1是一种多功能蛋白，主要作用是通过催化紧邻损伤的磷酸二酯主干的水解切口，启动DNA中无尿嘧啶/无嘧啶（AP）位点的修复。除了在双链DNA中，Ape1已被证明在许多生物学上相关的DNA构象的单链区域和结构化单链DNA中的AP位点进行切割。这些研究的延伸揭示了Ape1发挥AP内切酶活性的更广泛的模型底物。特别是，Ape1具有切割位于以下位置的AP位点的能力：(i) DNA/RNA杂交体的DNA链，（ii）设计用于模拟停滞复制或转录中间体的“伪三重”泡底物，以及（iii）模拟类开关重组过程中出现的r环结构的配置。此外，Ape1被发现可以切割含有ap位点的单链RNA，这表明它具有一种新的“清洁”功能，可能有助于消除有害的细胞AP-RNA分子。最后，在双链DNA中，直接围绕一个基本位点的序列上下文被发现对Ape1切割效率的影响小于三倍，而ATP被发现对Ape1在双链底物上的内切酶能力产生复杂的影响。结果表明，除了常规双工基因组DNA中的基本位点外，Ape1还具有切割DNA复制、转录和类开关重组过程中形成的DNA构象中的AP位点的能力，并且Ape1可以内核分解破坏受损的RNA。Elsevier Ltd.出版。
Human Ape1 is a multifunctional protein with a major role in initiating repair of apurinic/apyrimidinic (AP) sites in DNA by catalyzing hydrolytic incision of the phosphodiester backbone immediately adjacent to the damage. Besides in double-stranded DNA, Ape1 has been shown to cleave at AP sites in single-stranded regions of a number of biologically relevant DNA conformations and in structured single-stranded DNA. Extension of these studies has revealed a more expansive repertoire of model substrates on which Ape1 exerts AP endonuclease activity. In particular, Ape1 possesses the ability to cleave at AP sites located in (i) the DNA strand of a DNA/RNA hybrid, (ii) "pseudo-triplex" bubble substrates designed to mimic stalled replication or transcription intermediates, and (iii) configurations that emulate R-loop structures that arise during class switch recombination. Moreover, Ape1 was found to cleave AP-site-containing single-stranded RNA, suggesting a novel "cleansing" function that may contribute to the elimination of detrimental cellular AP-RNA molecules. Finally, sequence context immediately surrounding an abasic site in duplex DNA was found to have a less than threefold effect on the incision efficiency of Ape1, and ATP was found to exert complex effects on the endonuclease capacity of Ape1 on double-stranded substrates. The results suggest that in addition to abasic sites in conventional duplex genomic DNA, Ape1 has the ability to incise at AP sites in DNA conformations formed during DNA replication, transcription, and class switch recombination, and that Ape1 can endonucleolytically destroy damaged RNA. Published by Elsevier Ltd.