Abstract：
Chromatin dynamics play essential roles in transcriptional regulation. The chromodomain helicase DNA-binding domain 3 (CHD3) chromatin remodeler PICKLE (PKL) and HISTONE DEACETYLASE6 (HDA6) are required for transcriptional gene silencing, but their coordinated function in gene repression requires further study. Through a genetic suppressor screen, we found that a point mutation at PKL could partially restore the developmental defects of a weak Polycomb repressive complex 1 (PRC1) mutant (ring1a-2 ring1b-3), in which RING1A expression is suppressed by a T-DNA insertion at the promoter. Compared to ring1a-2 ring1b-3, the expression of RING1A is increased, nucleosome occupancy is reduced, and the histone 3 lysine 9 acetylation (H3K9ac) level is increased at the RING1A locus in the pkl ring1a-2 ring1b-3 triple mutant. HDA6 interacts with PKL and represses RING1A expression similarly to PKL genetically and molecularly in the ring1a-2 ring1b-3 background. Furthermore, we show that PKL and HDA6 suppress the expression of a set of genes and transposable elements (TEs) by increasing nucleosome density and reducing H3K9ac. Genome-wide analysis indicated they possibly coordinately maintain DNA methylation as well. Our findings suggest that PKL and HDA6 function together to reduce H3K9ac and increase nucleosome occupancy, thereby facilitating gene/TE regulation in Arabidopsis (Arabidopsis thaliana).
摘要：
染色质动力学在转录调控中起重要作用。色域解旋酶DNA结合域3（CHD3）染色质重塑因子PICKLE（PKL）和HISTONEDEACETYLASE6（HDA6）是转录基因沉默所必需的，但是它们在基因抑制中的协调功能需要进一步研究。通过基因抑制筛选，我们发现，PKL的点突变可以部分恢复弱Polycomb抑制复合物1（PRC1）突变体（ring1a-2ring1b-3）的发育缺陷，其中RING1A表达被启动子处的T-DNA插入抑制。与ring1a-2ring1b-3相比，RING1A的表达增加，核小体占用减少，在pklring1a-2ring1b-3三重突变体中，RING1A基因座的组蛋白3赖氨酸9乙酰化（H3K9ac）水平增加。HDA6与PKL相互作用，并在环1a-2环1b-3背景中与PKL在遗传和分子上相似地抑制RING1A表达。此外，我们显示PKL和HDA6通过增加核小体密度和减少H3K9ac来抑制一组基因和转座因子（TE）的表达。全基因组分析表明，它们也可能协调维持DNA甲基化。我们的研究结果表明，PKL和HDA6共同发挥作用，以减少H3K9ac和增加核小体占有率，从而促进拟南芥(拟南芥)中的基因/TE调控。
