Telobox motifs recruit CLF/SWN–PRC2 for H3K27me3 deposition via TRB factors in Arabidopsis

First author: Yue Zhou; Affiliations: Max Planck Institute for Plant Breeding Research (德国马克斯普朗克遗传发育生物学研究所): Köln, Germany

Corresponding author: Franziska Turck

Polycomb repressive complexes (PRCs; 多梳抑制复合物) control organismic development in higher eukaryotes through epigenetic gene repression. PRC proteins do not contain DNA-binding domains, thus prompting questions regarding how PRCs find their target loci. Here we present genome-wide evidence of PRC2 recruitment by telomere-repeat-binding factors (TRBs) through telobox-related motifs in Arabidopsis. A triple trb1-2, trb2-1, and trb3-2 (trb1/2/3) mutant with a developmental phenotype and a transcriptome strikingly similar to those of strong PRC2 mutants showed redistribution of trimethyl histone H3 Lys27 (H3K27me3) marks and lower H3K27me3 levels, which were correlated with derepression (去阻遏) of TRB1-target genes. TRB1–3 physically interacted with the PRC2 proteins CLF and SWN. A SEP3 reporter gene with a telobox mutation showed ectopic expression, which was correlated with H3K27me3 depletion, whereas tethering (拴住) TRB1 to the mutated cis element partially restored repression. We propose that telobox-related motifs recruit PRC2 through the interaction between TRBs and CLF/SWN, a mechanism essential for H3K27me3 deposition at a subset of target genes.

在高等真核生物中，多梳抑制复合物PRCs通过表观基因抑制控制着器官的发育。PRC蛋白并不含有DNA结合结构域，因此PRCs是如何结合到其靶基因位点的还是一个有待解决的问题。本文报道了拟南芥中端粒重复结合因子TRB通过telobox基序招募PRC2。trb1-2、trb2-1和trb3-2三突变体的表型和转录组与PRC2突变体较为相似，两者均显示H3K27me3的再分配以及低水平的H3K27me3，这与TRB1靶基因的去阻遏相关。TRB1–3能够与PRC2蛋白CLF和SWN相互作用。一个带有telobox突变的SEP3报告基因显示出异位表达，这与H3K27me3的耗尽相关，会将TRB1紧紧拴在突变了的顺式作用元件上，部分恢复抑制作用。作者假设telobox基序通过TRBs与CLF/SWN之间的相互作用招募PRC2，该机制能够促进H3K27me3在一些靶基因上的沉积。

通讯：Franziska Turck (http://www.mpipz.mpg.de/turck)

研究方向：序列特异性转录因子和影响染色质结构的蛋白复合物之间的互作对于基因表达的调控。

doi: 10.1038/s41588-018-0109-9

Journal: Nature Genetics

Published online: 26 April, 2018

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