Assembly and disassembly of nucleosome core particles containing histone variants by human nucleosome assembly protein I
Assembly and disassembly of nucleosome core particles containing histone variants by human nucleosome assembly protein I
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DOI：
10.1128/mcb.25.23.10639-10651.2005
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发表时间：
2005-12-01
影响因子：
5.3
通讯作者：
Nagata, K
中科院分区：
文献类型：
--
作者：
Okuwaki, M;Kato, K;Nagata, K
组蛋白变异在染色质结构的维持和调节中发挥重要作用。为了表征含有组蛋白变体的染色质结构的生化特性，我们研究了用重组组蛋白组装的核小体核心颗粒（NCP）的动态状态。我们发现，在核小体组装蛋白 I (NAP-I)（一种组蛋白伴侣）存在的情况下，H2A-Barr 体缺陷型 (H2A.Bbd) 赋予迄今为止已知的哺乳动物组蛋白 H2A 变体中最灵活的核小体结构。 NAP-I 介导 NCP 中 H2A.Bbd-H2B 二聚体的有效组装和分解。当 NCP 含有 H3.3（一种已知位于活性染色质中的组蛋白 H3 变体）时，该反应比 NCP 含有典型 H3 时更有效地完成。这些观察结果表明组蛋白变体 H2A.Bbd 和 H3.3 参与活性染色质结构的形成和维持。我们还观察到酸性组蛋白结合蛋白 TAF-I/SET 和 B23.1 表现出二聚体组装和拆卸活性，但其活性效率明显低于 NAP-I。因此，NAP-I及其其他功能结构的酸性性质对于介导NCP中二聚体的组装和解聚可能是必需的。
Histone variants play important roles in the maintenance and regulation of the chromatin structure. In order to characterize the biochemical properties of the chromatin structure containing histone variants, we investigated the dynamic status of nucleosome core particles (NCPs) that were assembled with recombinant histones. We found that in the presence of nucleosome assembly protein I (NAP-I), a histone chaperone, H2A-Barr body deficient (H2A.Bbd) confers the most flexible nucleosome structure among the mammalian histone H2A variants known thus far. NAP-I mediated the efficient assembly and disassembly of the H2A.Bbd-H2B dimers from NCPs. This reaction was accomplished more efficiently when the NCPs contained H3.3, a histone H3 variant known to be localized in the active chromatin, than when the NCPs contained the canonical H3. These observations indicate that the histone variants H2A.Bbd and H3.3 are involved in the formation and maintenance of the active chromatin structure. We also observed that acidic histone binding proteins, TAF-I/SET and B23.1, demonstrated dimer assembly and disassembly activity, but the efficiency of their activity was considerably lower than that of NAP-I. Thus, both the acidic nature of NAP-I and its other functional structure(s) may be essential to mediate the assembly and disassembly of the dimers in NCPs.