Enhancement of camptothecin-induced topoisomerase I cleavage complexes by the acetaldehyde adduct N2-ethyl-2′-deoxyguanosine
Enhancement of camptothecin-induced topoisomerase I cleavage complexes by the acetaldehyde adduct N2-ethyl-2′-deoxyguanosine
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DOI：
10.1093/nar/gkh902
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发表时间：
2004-01-01
影响因子：
14.9
通讯作者：
Pommier, Y
中科院分区：
文献类型：
--
作者：
Antony, S;Theruvathu, JA;Pommier, Y
DNA拓扑异构酶I（Top1）是一种调节DNA拓扑结构的酶，其活性受到DNA结构改变和抗癌生物碱喜树碱（CPT）的影响。在这里，我们评估了乙酰丙酮衍生的DNA加合物，N-2-乙基-2 '-脱氧鸟苷（N-2-乙基-dG），对人类Top1切口和关闭活动的影响。使用纯化的重组Top1，我们表明，Top1切口关闭活性保持不受影响的N-2-乙基-dG加合物寡核苷酸。然而，N-2-乙基-dG加合物增强了CPT诱导的Top1-DNA切割复合物，这取决于N-2-乙基-dG加合物相对于Top1切割位点的相对位置。当N-2-乙基-dG加合物紧邻Top1位点的3'端（位置+1）时，Top1介导的DNA再连接（闭合）被选择性抑制。此外，当N-2-乙基-dG加合物位于-5位时，CPT增强了与加合物紧邻的替代Top1裂解位点处的裂解，该加合物然后位于相对于该新的替代Top1位点的+1位。建模研究表明，位于Top1位点5'端（位置+1）的N-2-乙基-dG加合物上的乙基在空间上阻断CPT从Top1-DNA复合物的解离，从而进一步抑制再连接（闭合）反应。
The activity of DNA topoisomerase I (Top1), an enzyme that regulates DNA topology, is impacted by DNA structure alterations and by the anticancer alkaloid camptothecin (CPT). Here, we evaluated the effect of the acetaldehyde-derived DNA adduct, N-2-ethyl-2'-deoxyguanosine (N-2-ethyl-dG), on human Top1 nicking and closing activities. Using purified recombinant Top1, we show that Top1 nicking-closing activity remains unaffected in N-2-ethyl-dG adducted oligonucleotides. However, the N-2-ethyl-dG adduct enhanced CPT-induced Top1-DNA cleavage complexes depending on the relative position of the N-2-ethyl-dG adduct with respect to the Top1 cleavage site. The Top1-mediated DNA religation (closing) was selectively inhibited when the N-2-ethyl-dG adduct was present immediately 3' from the Top1 site (position +1). In addition, when the N-2-ethyl-dG adduct was located at the -5 position, CPT enhanced cleavage at an alternate Top1 cleavage site immediately adjacent to the adduct, which was then at position +1 relative to this new alternate Top1 site. Modeling studies suggest that the ethyl group on the N-2-ethyl-dG adduct located at the 5' end of a Top1 site (position +1) sterically blocks the dissociation of CPT from the Top1-DNA complex, thereby inhibiting further the religation (closing) reaction.