Laboratory of Structural Biology, Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan ; RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
FEBS Open Bio. 2013 Aug 22;3:363-9. doi: 10.1016/j.fob.2013.08.007. eCollection 2013.
Histones are the protein components of the nucleosome, which forms the basic architecture of eukaryotic chromatin. Histones H2A, H2B, H3, and H4 are composed of two common regions, the "histone fold" and the "histone tail". Many efforts have been focused on the mechanisms by which the post-translational modifications of histone tails regulate the higher-order chromatin architecture. On the other hand, previous biochemical studies have suggested that histone tails also affect the structure and stability of the nucleosome core particle itself. However, the precise contributions of each histone tail are unclear. In the present study, we determined the crystal structures of four mutant nucleosomes, in which one of the four histones, H2A, H2B, H3, or H4, lacked the N-terminal tail. We found that the deletion of the H2B or H3 N-terminal tail affected histone-DNA interactions and substantially decreased nucleosome stability. These findings provide important information for understanding the complex roles of histone tails in regulating chromatin structure.
组蛋白是核小体的蛋白质成分，核小体形成真核染色质的基本结构。组蛋白 H2A、H2B、H3 和 H4 由两个共同区域组成，即“组蛋白折叠”和“组蛋白尾部”。许多研究都集中在组蛋白尾部的翻译后修饰如何调节更高阶的染色质结构的机制上。另一方面，以前的生化研究表明，组蛋白尾部也会影响核小体核心颗粒本身的结构和稳定性。然而，每个组蛋白尾部的确切贡献尚不清楚。在本研究中，我们确定了四个突变核小体的晶体结构，其中四个组蛋白之一，H2A、H2B、H3 或 H4，缺乏 N 端尾部。我们发现 H2B 或 H3 N 端尾部的缺失会影响组蛋白-DNA 相互作用，并显著降低核小体的稳定性。这些发现为理解组蛋白尾部在调节染色质结构中的复杂作用提供了重要信息。
