Topoisomerase II, scaffold component, promotes chromatin compaction in vitro in a linker-histone H1-dependent manner
Topoisomerase II, scaffold component, promotes chromatin compaction in vitro in a linker-histone H1-dependent manner
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DOI：
10.1093/nar/gkm116
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发表时间：
2007-04-01
影响因子：
14.9
通讯作者：
Takeyasu, Kunio
中科院分区：
文献类型：
--
作者：
Hizume, Kohji;Araki, Sumiko;Takeyasu, Kunio
拓扑异构酶 II (Topo II) 是染色体支架的主要成分，对于有丝分裂染色体浓缩至关重要，但其作用机制仍不清楚。在这里，我们使用体外染色质重建系统结合原子力和荧光显微镜分析来确定 Topo II 如何影响染色体结构。即使在没有 ATP 的情况下，Topo II 也会与裸露的 DNA 结合并将两条 DNA 链夹在一起。此外，Topo II 以依赖于组蛋白 H1 但不依赖于 ATP 的方式促进染色质压缩。组蛋白 H1 诱导的 30 nm 染色质纤维被 Topo II 转化为大型复合物。对 40,6-二脒基-2-苯基吲哚染色的染色质布朗运动的荧光显微镜分析表明，在组蛋白 H1 存在但不存在的情况下，添加 Topo II 后重建的染色质变得更大。基于这些发现，我们提出染色质堆积是由组蛋白 H1 依赖性、Topo II 介导的 DNA 链夹紧触发的。
TopoisomeraseII (Topo II) is a major component of chromosomal scaffolds and essential for mitotic chromosome condensation, but the mechanism of this action remains unknown. Here, we used an in vitro chromatin reconstitution system in combination with atomic force and fluorescence microscopic analyses to determine how Topo II affects chromosomal structure. Topo II bound to bare DNA and clamped the two DNA strands together, even in the absence of ATP. In addition, Topo II promoted chromatin compaction in a manner dependent on histone H1 but independent of ATP. Histone H1-induced 30-nm chromatin fibers were converted into a large complex by Topo II. Fluorescence microscopic analysis of the Brownian motion of chromatin stained with 40,6-diamidino-2-phenylindole showed that the reconstituted chromatin became larger following the addition of Topo II in the presence but not the absence of histone H1. Based on these findings, we propose that chromatin packing is triggered by histone H1-dependent, Topo II-mediated clamping of DNA strands.