A plant‐specific SWR1 chromatin‐remodeling complex couples histone H2A.Z deposition with nucleosome sliding

First author: Yu‐Xi Luo; Affiliations: National Institute of Biological Sciences (北京生命科学研究所): Beijing, China

Corresponding author: Xin‐Jian He

Deposition of H2A.Z in chromatin is known to be mediated by a conserved SWR1 chromatin‐remodeling complex in eukaryotes. However, little is known about whether and how the SWR1 complex cooperates with other chromatin regulators. Using immunoprecipitation followed by mass spectrometry, we found all known components of the Arabidopsis thaliana SWR1 complex and additionally identified the following three classes of previously uncharacterized plant‐specific SWR1 components: MBD9, a methyl‐CpG‐binding domain‐containing protein; CHR11 and CHR17 (CHR11/17), ISWI chromatin remodelers responsible for nucleosome sliding; and TRA1a and TRA1b, accessory subunits of the conserved NuA4 histone acetyltransferase complex. MBD9 directly interacts with CHR11/17 and the SWR1 catalytic subunit PIE1, and is responsible for the association of CHR11/17 with the SWR1 complex. MBD9, TRA1a, and TRA1b function as canonical components of the SWR1 complex to mediate H2A.Z deposition. CHR11/17 are not only responsible for nucleosome sliding but also involved in H2A.Z deposition. These results indicate that the association of the SWR1 complex with CHR11/17 may facilitate the coupling of H2A.Z deposition with nucleosome sliding, thereby co‐regulating gene expression, development, and flowering time.

真核生物中，H2A.Z在染色质上的沉积是由一个保守的SWR1染色质重塑复合体所介导的。然而，我们对于SWR1复合体是否以及如何与其它染色质调控因子相互协作还不清楚。本文的研究中，作者结合免疫沉淀（immunoprecipitation）与质谱（mass spectrometry），鉴定了拟南芥中所有的SWR1复合体组分，另外还鉴定了三类先前未知功能的植物特异性SWR1复合体组分，分别是一个含甲基CpG结合结构域的蛋白MBD9、两个作用于核小体滑动（nucleosome sliding）的ISWI染色质重塑因子CHR11/17以及两个保守NuA4组蛋白乙酰转移酶复合物的辅助亚基TRA1a和TRA1b。MBD9能够直接与CHR11/17和SWR1催化亚基PIE1发生互作，并且作用于CHR11/17与SWR1复合体的关联。另外，MBD9、TRA1a和TRA1b对于SWR1复合体介导H2A.Z沉积是必要的组分。此外，CHR11/17不仅作用于核小体的滑动，同样还参与了H2A.Z的沉积。这些发现揭示了SWR1复合体与CHR11/17之间的关联可能促进了H2A.Z沉积与核小体滑动之间的偶联，因此共调控拟南芥的基因表达、发育以及开花时间。

通讯：何新建 (http://www.nibs.ac.cn/yjsjyimgshow.php?cid=5&sid=6&id=766)

个人简介：1997年，南京师范大学，学士；2000年，南京农业大学，硕士；2004年，中科院遗传与发育生物学研究所，博士；2004-2006年，美国爱荷华大学，博士后；2006-2009年，美国加州大学河滨分校，博士后；2010-2015年，北京生命科学研究所，研究员；2015年-至今，北京生命科学研究所，高级研究员。

研究方向：利用模式植物拟南芥为研究材料，通过利用遗传、分子和生化方法重点研究RNA指导的DNA甲基化和组蛋白修饰途径。

doi: https://doi.org/10.15252/embj.2019102008

Journal: EMBO J

Published date: March 02, 2020