Newly replicated DNA is associated with DNA topoisomerase II in cultured rat prostatic adenocarcinoma cells
Newly replicated DNA is associated with DNA topoisomerase II in cultured rat prostatic adenocarcinoma cells
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DOI：
10.1038/322187a0
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发表时间：
1986-07
期刊：
影响因子：
64.8
通讯作者：
W. Nelson;Leroy F. Liu;D. S. Coffey
中科院分区：
文献类型：
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作者：
W. Nelson;Leroy F. Liu;D. S. Coffey
已经提出DNA拓扑异构酶在原核生物和真核生物中的多种遗传过程中起作用1 -3。在这里，我们已经评估了DNA拓扑异构酶II在哺乳动物DNA复制的作用，通过确定新合成的DNA的共价酶-DNA复合物处理培养的大鼠前列腺腺癌细胞与替尼泊苷产生的接近。替尼泊苷（VM-26）是一种表鬼白毒素，已知可与哺乳动物DNA拓扑异构酶II相互作用，从而将该酶捕获在与DNA 4 -9的共价复合物中。我们已经发现，替尼泊苷诱导的捕获这种复合物需要氯化镁，由ATP刺激，并抑制新生霉素。共价复合物的形成似乎是可逆的去除替尼泊苷。此外，3 H-胸苷脉冲标记的DNA和拓扑异构酶II之间形成的共价复合物的分析后替尼泊苷治疗揭示了一个直接协会的酶与新生的DNA片段。我们的研究结果表明，DNA拓扑异构酶II可能与哺乳动物细胞中DNA复制叉附近的新复制的子DNA分子相互作用。
DNA topoisomerases have been proposed to function in a variety of genetic processes in both prokaryotes and eukaryotes1–3. Here, we have assessed the role of DNA topoisomerase II in mammalian DNA replication by determining the proximity of newly synthesized DNA to covalent enzyme–DNA complexes generated by treating cultured rat prostatic adenocarcinoma cells with teniposide. Teniposide (VM-26), an epipodophyllotoxin, is known to interact with mammalian DNA topoisomerase II so as to trap the enzyme in a covalent complex with DNA4–9. We have found that the teniposide-induced trapping of such complexes requires MgCl2, is stimulated by ATP and is inhibited by novobiocin. The formation of covalent complexes seems to be reversible on removal of teniposide. Furthermore, analysis of the covalent complexes formed between3H-thymidine pulse-labelled DNA and topoisomerase II following teniposide treatment reveals a direct association of the enzyme with nascent DNA fragments. Our results suggest that DNA topoisomerase II may interact with newly replicated daughter DNA molecules near DNA replication forks in mammalian cells.