Identification of the amino acid residues responsible for stable nucleosome formation by histone H3.Y.
Identification of the amino acid residues responsible for stable nucleosome formation by histone H3.Y.
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通过组蛋白 H3.Y 鉴定负责稳定核小体形成的氨基酸残基。
DOI：
10.1080/19491034.2016.1277303
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
Kurumizaka H.
中科院分区：
文献类型：
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作者：
Kujirai T;Horikoshi N;Xie Y;Taguchi H;Kurumizaka H.
组蛋白H3.Y在灵长类动物中保守。我们以前报道过，外源产生的H3.Y聚集在转录起始点附近，表明它可能在转录调控中发挥作用。H3.Y核小体与柔韧的DNA末端形成松弛的染色质构象。H3.Y特异的Lys42残基在一定程度上增强了核小体DNA的灵活性。令我们惊讶的是，我们在体内和体外发现H3.Y稳定地与染色质和核小体结合。然而，导致其稳定核小体掺入的H3.Y残基尚未确定。在本研究中，我们对H3.Y进行了全面的突变分析，并确定了H3.Y的C-末端区域，包括氨基酸残基124-135，是其与DNA稳定结合的原因。在H3.Y C末端残基中，H3.Y Met124残基显著促进了DNA与H3.Y-H4四聚体的稳定结合。H3.Y M124I突变显著降低了核小体中H3.Y-H4的结合。相反，H3.Y K42R突变对核小体稳定性的影响较小，尽管它有助于核小体的柔性DNA末端。因此，这些H3.Y特异残基Lys42和Met124分别在染色质中的核小体DNA松弛和稳定的核小体形成中发挥不同和特定的作用。
Histone H3.Y is conserved among primates. We previously reported that exogenously produced H3.Y accumulates around transcription start sites, suggesting that it may play a role in transcription regulation. The H3.Y nucleosome forms a relaxed chromatin conformation with flexible DNA ends. The H3.Y-specific Lys42 residue is partly responsible for enhancing the flexibility of the nucleosomal DNA. To our surprise, we found that H3.Y stably associates with chromatin and nucleosomesin vivoandin vitro. However, the H3.Y residues responsible for its stable nucleosome incorporation have not been identified yet. In the present study, we performed comprehensive mutational analyses of H3.Y, and determined that the H3.Y C-terminal region including amino acid residues 124–135 is responsible for its stable association with DNA. Among the H3.Y C-terminal residues, the H3.Y Met124 residue significantly contributed to the stable DNA association with the H3.Y-H4 tetramer. The H3.Y M124I mutation substantially reduced the H3.Y-H4 association in the nucleosome. In contrast, the H3.Y K42R mutation affected the nucleosome stability less, although it contributes to the flexible DNA ends of the nucleosome. Therefore, these H3.Y-specific residues, Lys42 and Met124, play different and specific roles in nucleosomal DNA relaxation and stable nucleosome formation, respectively, in chromatin.