Topoisomerase II inactivation prevents the completion of DNA replication in budding yeast
Topoisomerase II inactivation prevents the completion of DNA replication in budding yeast
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DOI：
10.1016/j.molcel.2008.04.019
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发表时间：
2008-06-20
期刊：
影响因子：
16
通讯作者：
Diffley, John F. X.
中科院分区：
文献类型：
--
作者：
Baxter, Jonathan;Diffley, John F. X.
II型拓扑异构酶是解析拓扑异构双链DNA所必需的。尽管抗拓扑异构酶2（Top2）药物是临床上重要的抗生素和化学疗法，但据我们所知，通过Top2耗尽和失活的细胞杀伤机制从未被直接比较。我们发现，从芽殖酵母细胞中的Top2蛋白的耗尽防止DNA在S期的decatenation。细胞完成DNA复制并按计划进入随后的有丝分裂，遭受广泛的染色体错误分离。通过不完全分离的染色体的胞质分裂导致致命的DNA损伤。相比之下，无催化活性的Top2的表达导致稳定的G2停滞，需要完整的DNA损伤检查点。检查点激活与无法完成DNA复制相关，导致超连锁、有间隙的子DNA分子。因此，Top2缺失和失活通过不同的机制杀死细胞，这对理解连锁检查点的性质、DNA复制如何终止、抗Top2药物如何起作用以及如何设计新药具有重要意义。
Type II topoisomerases are essential for resolving topologically entwined double-stranded DNA. Although anti-topoisomerase 2 (Top2) drugs are clinically important antibiotics and chemotherapies, to our knowledge, the mechanisms of cell killing by Top2 depletion and inactivation have never been directly compared. We show that depletion of Top2 protein from budding yeast cells prevents DNA decatenation during S phase. Cells complete DNA replication and enter the ensuing mitosis on schedule, suffering extensive chromosome missegregation. Cytokinesis through incompletely segregated chromosomes causes lethal DNA damage. By contrast, expression of catalytically inactive Top2 causes a stable G2 arrest requiring an intact DNA damage checkpoint. Checkpoint activation correlates with an inability to complete DNA replication, resulting in hypercatenated, gapped daughter DNA molecules. Thus, Top2 depletion and inactivation kill cells by different mechanisms, which has implications for understanding the nature of the catenation checkpoint, how DNA replication terminates, how anti-Top2 drugs work, and how new drugs might be designed.