The core histone N termini function independently of linker histones during chromatin condensation
The core histone N termini function independently of linker histones during chromatin condensation
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DOI：
10.1074/jbc.m006801200
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发表时间：
2000-11-24
影响因子：
4.8
通讯作者：
Hansen, JC
中科院分区：
文献类型：
--
作者：
Carruthers, LM;Hansen, JC
在染色质组装和盐依赖性染色质凝聚过程中，核心组蛋白N末端和连接体组蛋白之间的关系进行了研究，使用定义的染色质模型系统重建串联重复的5 S rDNA，组蛋白H5，无论是天然的“完整”核心组蛋白八聚体或“无尾”组蛋白八聚体缺乏其N-末端结构域。核酸酶消化和沉降研究表明，H5结合和由此产生的限制进入和退出核小体DNA发生在无尾和完整的染色质阵列在相同的程度上。然而，尽管具有正常的染色体结构，无尾染色质阵列既不能浓缩成广泛折叠的结构，也不能在MgCl 2中协同寡聚化。缺乏连接体组蛋白的无尾核小体阵列也不能广泛折叠或寡聚化，表明核心组蛋白N末端在盐依赖性缩合期间执行相同的功能，而不管连接体组蛋白是否是阵列的组分。我们的研究结果进一步表明，在体外核心组蛋白N末端功能的破坏允许一个接头组蛋白含有染色质纤维存在于解压缩状态下的条件下，通常会促进广泛的纤维凝聚。这些发现对染色质凝聚的机制和染色质对基因组功能的调节都有重要意义。
The relationships between the core histone N termini and linker histones during chromatin assembly and salt-dependent chromatin condensation were investigated using defined chromatin model systems reconstituted from tandemly repeated 5 S rDNA, histone H5, and either native "intact" core histone octamers or "tailless" histone octamers lacking their N-terminal domains. Nuclease digestion and sedimentation studies indicate that H5 binding and the resulting constraint of entering and exiting nucleosomal DNA occur to the same extent in both tailless and intact chromatin arrays. However, despite possessing a normal chromatosomal structure, tailless chromatin arrays can neither condense into extensively folded structures nor cooperatively oligomerize in MgCl2. Tailless nucleosomal arrays lacking linker histones also are unable to either fold extensively or oligomerize, demonstrating that the core histone N termini perform the same functions during salt-dependent condensation regardless of whether linker histones are components of the array. Our results further indicate that disruption of core histone N termini function in vitro allows a linker histone-containing chromatin fiber to exist in a decondensed state under conditions that normally would promote extensive fiber condensation. These findings have key implications for both the mechanism of chromatin condensation, and the regulation of genomic function by chromatin.