Crystal Structure and Characterization of Novel Human Histone H3 Variants, H3.6, H3.7, and H3.8
Crystal Structure and Characterization of Novel Human Histone H3 Variants, H3.6, H3.7, and H3.8
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新型人类组蛋白 H3 变体、H3.6、H3.7 和 H3.8 的晶体结构和表征
DOI：
10.1021/acs.biochem.6b01098
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发表时间：
2017
期刊：
影响因子：
2.9
通讯作者：
Kurumizaka H.
中科院分区：
文献类型：
--
作者：
Taguchi H;Xie Y;Horikoshi N;Maehara K;Harada A;Nogami J;Sato K;Arimura Y;Osakabe A;Kujirai T;Iwasaki T;Semba Y;Tachibana T;Kimura H;Ohkawa Y;Kurumizaka H.
非等位基因的组蛋白变异体被认为是真核染色体中调节基因组DNA功能的表观遗传因子。在这项研究中，我们鉴定了三个新的人类组蛋白H3变体(命名为H3.6、H3.7和H3.8)，它们以前被注释为伪基因。H3.6和H3.8保存H3.3特有的氨基酸残基，而H3.7与H3.1共享特异氨基酸残基。我们成功地在体外重组了含H3.6In的核小体，并测定了其晶体结构。在H3.6核小体中，H3.6特异的Val62残基与同源H4分子疏水接触，但其接触面积小于相应的H3.3Ile62残基。热稳定性分析表明，与H3.3核小体相比，H3.6核小体实质上是不稳定的。有趣的是，突变分析表明H3.6Val62残基是H3.6核小体不稳定的完全原因，可能是因为与H4的疏水相互作用减弱。我们还重组了含有H3.8的核小体，但其热稳定性很低。相反，纯化的H3.7在体外不能形成核小体。这些新的人类组蛋白H3变异体的鉴定和表征为理解人类基因组的表观遗传调控提供了重要的新见解。
Non-allelic histone variants are considered as epigenetic factors that regulate genomic DNA functions in eukaryotic chromosomes. In this study, we identified three new human histone H3 variants (named H3.6, H3.7, and H3.8), which were previously annotated as pseudogenes. H3.6 and H3.8 conserve the H3.3-specific amino acid residues, but H3.7 shares the specific amino acid residues with H3.1. We successfully reconstituted the nucleosome containing H3.6in vitroand determined its crystal structure. In the H3.6 nucleosome, the H3.6-specific Val62 residue hydrophobically contacts the cognate H4 molecule, but its contact area is smaller than that of the corresponding H3.3 Ile62 residue. The thermal stability assay revealed that the H3.6 nucleosome is substantially unstable, as compared to the H3.3 nucleosome. Interestingly, mutational analysis demonstrated that the H3.6 Val62 residue is fully responsible for the H3.6 nucleosome instability, probably because of the weakened hydrophobic interaction with H4. We also reconstituted the nucleosome containing H3.8, but its thermal stability was quite low. In contrast, purified H3.7 failed to form nucleosomesin vitro. The identification and characterization of these novel human histone H3 variants provide important new insights into understanding the epigenetic regulation of the human genome.