Intrinsic Nucleic Acid-Binding Activity of Chp1 Chromodomain Is Required for Heterochromatic Gene Silencing
Intrinsic Nucleic Acid-Binding Activity of Chp1 Chromodomain Is Required for Heterochromatic Gene Silencing
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DOI：
10.1016/j.molcel.2012.05.017
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发表时间：
2012-07-27
期刊：
影响因子：
16
通讯作者：
Nakayama, Jun-ichi
中科院分区：
文献类型：
--
作者：
Ishida, Mayumi;Shimojo, Hideaki;Nakayama, Jun-ichi
裂殖酵母中的着丝粒异钟蛋白组装需要RNAi途径。Chp 1是一种染色体结构域（CD）蛋白，形成含有Ago 1的RNA诱导的转录沉默（RITS）复合物，并通过其CD将siRNA结合的RITS募集到甲基化组蛋白H3赖氨酸9（H3 K9 me）。在这里，我们表明，CD的Chp 1（Chp 1-CD）具有独特的核酸结合活性，是必不可少的异染色质基因沉默。详细的荧光迁移率变化分析表明，Chp 1结合RNA通过CD除了其中央RNA识别基序。有趣的是，当Chp 1-CD与H3 K9 me结合时，Chp 1-CD的稳健RNA和DNA结合活性强烈增强，通过结构分析发现这涉及Chp 1-CD内的带正电荷的结构域。这些结果证明了CD的作用，它提供了RNA、DNA和甲基化组蛋白尾部之间的连接，以确保异染色质基因沉默。
Centromeric heterochronnatin assembly in fission yeast requires the RNAi pathway. Chp1, a chromodomain (CD) protein, forms the Ago1-containing RNA-induced transcriptional silencing (RITS) complex and recruits siRNA-bound RITS to methylated histone H3 lysine 9 (H3K9me) via its CD. Here, we show that the CD of Chp1 (Chp1-CD) possesses unique nucleic acid-binding activities that are essential for heterochromatic gene silencing. Detailed electrophoretic-mobility shift analyses demonstrated that Chp1 binds to RNA via the CD in addition to its central RNA-recognition motif. Interestingly, robust RNA- and DNA-binding activity of Chp1-CD was strongly enhanced when it was bound to H3K9me, which was revealed to involve a positively charged domain within the Chp1-CD by structural analyses. These results demonstrate a role for the CD that provides a link between RNA, DNA, and methylated histone tails to ensure heterochromatic gene silencing.