The CBP/p300 histone acetyltransferases function as plant‐specific MEDIATOR subunits in Arabidopsis,Journal of Integrative Plant Biology

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The CBP/p300 histone acetyltransferases function as plant‐specific MEDIATOR subunits in Arabidopsis
Journal of Integrative Plant Biology ( IF 9.3 ) Pub Date : 2020-12-15 , DOI: 10.1111/jipb.13052
Jing Guo _{1,

2} , Long Wei ₁ , Shan-Shan Chen ₁ , Xue-Wei Cai ₁ , Yin-Na Su ₁ , Lin Li ₁ , She Chen _{1,

3} , Xin-Jian He _{1,

2,

3}

Affiliation

In eukaryotes, MEDIATOR is a conserved multi‐subunit complex that links transcription factors and RNA polymerase II and that thereby facilitates transcriptional initiation. Although the composition of MEDIATOR has been well studied in yeast and mammals, relatively little is known about the composition of MEDIATOR in plants. By affinity purification followed by mass spectrometry, we identified 28 conserved MEDIATOR subunits in Arabidopsis thaliana, including putative MEDIATOR subunits that were not previously validated. Our results indicated that MED34, MED35, MED36, and MED37 are not Arabidopsis MEDIATOR subunits, as previously proposed. Our results also revealed that two homologous CBP/p300 histone acetyltransferases, HAC1 and HAC5 (HAC1/5) are in fact plant‐specific MEDIATOR subunits. The MEDIATOR subunits MED8 and MED25 (MED8/25) are partially responsible for the association of MEDIATOR with HAC1/5, MED8/25 and HAC1/5 co‐regulate gene expression and thereby affect flowering time and floral development. Our in vitro observations indicated that MED8 and HAC1 form liquid‐like droplets by phase separation, and our in vivo observations indicated that these droplets co‐localize in the nuclear bodies at a subset of nuclei. The formation of liquid‐like droplets is required for MED8 to interact with RNA polymerase II. In summary, we have identified all of the components of Arabidopsis MEDIATOR and revealed the mechanism underlying the link of histone acetylation and transcriptional regulation.

中文翻译：

CBP/p300 组蛋白乙酰转移酶在拟南芥中作为植物特异性介质亚基发挥作用

在真核生物中，MEDIATOR 是一种保守的多亚基复合体，可连接转录因子和 RNA 聚合酶 II，从而促进转录起始。尽管已经在酵母和哺乳动物中对 MEDIATOR 的成分进行了充分研究，但对植物中 MEDIATOR 的成分知之甚少。通过亲和纯化和质谱分析，我们在拟南芥中鉴定了 28 个保守的 MEDIATOR 亚基，包括先前未验证的推定 MEDIATOR 亚基。我们的结果表明 MED34、MED35、MED36 和 MED37 不是拟南芥MEDIATOR 亚基，如前所述。我们的结果还表明，两种同源 CBP/p300 组蛋白乙酰转移酶 HAC1 和 HAC5（HAC1/5）实际上是植物特异性 MEDIATOR 亚基。MEDIATOR 亚基 MED8 和 MED25 (MED8/25) 部分负责 MEDIATOR 与 HAC1/5 的关联，MED8/25 和 HAC1/5 共同调节基因表达，从而影响开花时间和花发育。我们的体外观察表明 MED8 和 HAC1 通过相分离形成液体状液滴，我们的体内观察表明这些液滴共定位在核体中的一个子核中。MED8 与 RNA 聚合酶 II 相互作用需要形成液体状液滴。总之，我们已经确定了所有组件拟南芥MEDIATOR 并揭示了组蛋白乙酰化和转录调控联系的潜在机制。

更新日期：2020-12-15

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