Histone Chaperone Nap1 Is a Major Regulator of Histone H2A-H2B Dynamics at the Inducible GAL Locus
Histone Chaperone Nap1 Is a Major Regulator of Histone H2A-H2B Dynamics at the Inducible GAL Locus
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DOI：
10.1128/mcb.00835-15
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发表时间：
2016-04-01
影响因子：
5.3
通讯作者：
Stargell，Laurie A.
中科院分区：
文献类型：
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作者：
Chen，Xu;D'Arcy，Sheena;Stargell，Laurie A.
组蛋白分子伴侣，如核小体组装蛋白1（Nap 1），在维持染色质结构中起着关键作用。在这里，我们使用的GAL位点在酵母菌调查Nap 1的染色质结构和组蛋白动力学在不同的转录状态的影响。当GAL位点不表达时，缺乏Nap 1的细胞显示组蛋白H2 A-H2 B在该位点的积累，而不是组蛋白H3-H4。过量的H2 A-H2 B与核小体之间的连接DNA相互作用，并且这种相互作用不依赖于H2 A-H2 B对这些特定序列的固有DNA结合亲和力。当GAL位点被转录时，过量的H2 A-H2 B被逆转，并且在缺乏Nap 1的细胞中所有染色质结合的组蛋白的水平被耗尽。我们开发了一种体内系统来测量GAL位点的组蛋白交换，并观察到野生型细胞中该位点的交换速率存在相当大的差异。我们概括了这种变异性的玻璃体核小体重建，这表明DNA序列的组蛋白动力学的贡献。我们还发现Nap 1是转录依赖的H2 A-H2 B交换所必需的。总之，这些结果表明，Nap 1是必不可少的维持适当的染色质组成和调节H2 A-H2 Bin体内交换。
Histone chaperones, like nucleosome assembly protein 1 (Nap1), play a critical role in the maintenance of chromatin architecture. Here, we use theGALlocus inSaccharomyces cerevisiaeto investigate the influence of Nap1 on chromatin structure and histone dynamics during distinct transcriptional states. When theGALlocus is not expressed, cells lacking Nap1 show an accumulation of histone H2A-H2B but not histone H3-H4 at this locus. Excess H2A-H2B interacts with the linker DNA between nucleosomes, and the interaction is independent of the inherent DNA-binding affinity of H2A-H2B for these particular sequences as measuredin vitro. When theGALlocus is transcribed, excess H2A-H2B is reversed, and levels of all chromatin-bound histones are depleted in cells lacking Nap1. We developed anin vivosystem to measure histone exchange at theGALlocus and observed considerable variability in the rate of exchange across the locus in wild-type cells. We recapitulate this variability within vitronucleosome reconstitutions, which suggests a contribution of DNA sequence to histone dynamics. We also find that Nap1 is required for transcription-dependent H2A-H2B exchange. Altogether, these results indicate that Nap1 is essential for maintaining proper chromatin composition and modulating the exchange of H2A-H2Bin vivo.