Crystal structure of the overlapping dinucleosome composed of hexasome and octasome
Crystal structure of the overlapping dinucleosome composed of hexasome and octasome
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DOI：
10.1126/science.aak9867
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发表时间：
2017-04-14
期刊：
影响因子：
56.9
通讯作者：
Kurumizaka, Hitoshi
中科院分区：
文献类型：
--
作者：
Kato, Daiki;Osakabe, Akihisa;Kurumizaka, Hitoshi
核小体是动态实体，通过染色质重塑过程沿着 DNA 重新定位。由转换蔗糖不可发酵（SWI/SNF）重塑剂重新定位的核小体与邻近的核小体碰撞并形成中间的“重叠双核小体”。在这里，我们以 3.14 埃的分辨率报告了重叠双核小体的晶体结构，其中两个核小体相关联。在重叠的双核小体结构中，不寻常的“六体”核小体由传统组蛋白八聚体中缺少一个 H2A-H2B 二聚体的组蛋白六聚体组成，与典型的“八体”核小体接触，并且它们紧密结合。因此，大约 250 个碱基对的 DNA 左手缠绕三圈，六体和八体部分之间没有连接 DNA 片段。重叠的双核小体结构可能为理解染色质重塑过程中核小体重新定位如何发生提供重要信息。
Nucleosomes are dynamic entities that are repositioned along DNA by chromatin remodeling processes. A nucleosome repositioned by the switch-sucrose nonfermentable (SWI/SNF) remodeler collides with a neighbor and forms the intermediate" overlapping dinucleosome." Here, we report the crystal structure of the overlapping dinucleosome, in which two nucleosomes are associated, at 3.14-angstrom resolution. In the overlapping dinucleosome structure, the unusual "hexasome" nucleosome, composed of the histone hexamer lacking one H2A-H2B dimer from the conventional histone octamer, contacts the canonical "octasome" nucleosome, and they intimately associate. Consequently, about 250 base pairs of DNA are left-handedly wrapped in three turns, without a linker DNA segment between the hexasome and octasome moieties. The overlapping dinucleosome structure may provide important information to understand how nucleosome repositioning occurs during the chromatin remodeling process.