A novel action of human apurinic/apyrimidinic endonuclease -: Excision of L-configuration deoxyribonucleoside analogs from the 3′ termini of DNA
A novel action of human apurinic/apyrimidinic endonuclease -: Excision of L-configuration deoxyribonucleoside analogs from the 3′ termini of DNA
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DOI：
10.1074/jbc.m004082200
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发表时间：
2000-10-06
影响因子：
4.8
通讯作者：
Cheng, YC
中科院分区：
文献类型：
--
作者：
Chou, KM;Kukhanova, M;Cheng, YC
beta-L-二氧戊环-胞苷（L-OddC、BCH-4556、曲沙西他滨）是一种新型非天然立体化学核苷类似物，目前正在进行癌症治疗 II 期临床研究。该核苷类似物可被磷酸化并随后掺入 DNA 的 3' 末端。 L-OddC 的细胞毒性与 DNA 中 L-OddCMP 的量相关，这取决于 DNA 聚合酶的掺入和核酸外切酶的去除。在这里，我们报道了一种主要酶的纯化和鉴定，与 dCMP 相比，该酶可以优先去除人类细胞 DNA 3' 末端的 L-OddCMP。令人惊讶的是，我们发现这种酶是无嘌呤/无嘧啶核酸内切酶 (APE1) (1)，这是一种经过充分表征的 DNA 碱基切除修复蛋白，APE1 更倾向于从 DNA 3' 末端去除 L-构型核苷，而不是 D-构型核苷。这些脱氧胞苷类似物的去除效率如下：L-OddC > β-L-2',3'-二脱氧-2',3'-二脱氢-5-氟胞苷 > β-L-2',3'-二脱氧胞苷 > β-L-2',3'-二脱氧-3'-硫胞苷 > β-D-2',3'-二脱氧胞苷 > β-D-2',2'-二氟脱氧胞苷 > β-D-8'-脱氧胞苷大于或等于 β-D-阿拉伯呋喃糖基胞嘧啶。该报告首次证明核酸外切酶可以优先切除 L 构型核苷类似物。这一发现表明，APE1 可能对 L-OddC 或其他 L-核苷类似物的活性至关重要，并且可能在细胞中发挥以前未知的其他重要作用。
beta-L-Dioxolane-cytidine (L-OddC, BCH-4556, Troxacitabine) is a novel unnatural stereochemical nucleoside analog that is under phase II clinical study for cancer treatment. This nucleoside analog could be phosphorylated and subsequently incorporated into the 3' terminus of DNA. The cytotoxicity of L-OddC was correlated with the amount of L-OddCMP in DNA, which depends on the incorporation by DNA polymerases and the removal by exonucleases. Here we reported the purification and identification of the major enzyme that could preferentially remove L-OddCMP compared with dCMP from the 3' termini of DNA in human cells. Surprisingly, this enzyme was found to be apurinic/apyrimidinic endonuclease (APE1) (1), a well characterized DNA base excision repair protein, APE1 preferred to remove L- over D-configuration nucleosides from 3' termini of DNA. The efficiency of removal of these deoxycytidine analogs were as follows: L-OddC > beta-L-2',3'-dideoxy-2',3'-didehydro-5-fluorocytidine > beta-L-2',3'-dideoxycytidine > beta-L-2',3'-dideoxy-3'-thiocytidine > beta-D-2',3'-dideoxycytidine > beta-D-2',2'-difluorodeoxycytidine > beta-D-8'-deoxycytidine greater than or equal to beta-D-arabinofuranosylcytosine. This report is the first demonstration that an exonuclease can preferentially excise L-configuration nucleoside analogs. This discovery suggests that APE1 could be critical for the activity of L-OddC or other L-nucleoside analogs and may play additional important roles in cells that were not previously known.