Abstract：
Transcription factors (TFs) tightly control plant development by regulating gene expression. The phase separation of TFs plays a vital role in gene regulation. Many plant TFs have the potential to form phase-separated protein condensates; however, little is known about which TFs are regulated by phase separation and how it affects their roles in plant development. Here, we report that the rice (Oryza sativa) single Myb TF TELOMERE REPEAT-BINDING FACTOR 2 (TRBF2) is highly expressed in fast-growing tissues at the seedling stage. TRBF2 is a transcriptional repressor that binds to the transcriptional start site of thousands of genes. Mutation of TRBF2 leads to pleiotropic developmental defects and misexpression of many genes. TRBF2 displays characteristics consistent with phase separation in vivo and forms phase-separated condensates in vitro. The H1/H5 domain of TRBF2 plays a crucial role in phase separation, chromatin targeting and gene repression. Replacing the H1/H5 domain by a phase-separated intrinsically disordered region from Arabidopsis (Arabidopsis thaliana) AtSERRATE partially recovers the function of TRBF2 in gene repression in vitro and in transgenic plants. We also found that TRBF2 is required for trimethylation of histone H3 Lys27 (H3K27me3) deposition at specific genes and genome-wide. Our findings reveal that phase separation of TRBF2 facilitates gene repression in rice development.
摘要：
转录因子（TFs）通过调节基因表达来严格控制植物发育。TFs的相分离在基因调控中起着至关重要的作用。许多植物TFs有可能形成相分离的蛋白质缩合物；然而，关于哪些TFs受到相分离的调控以及它如何影响它们在植物发育中的作用知之甚少。这里,我们报告说，水稻（Oryzasativa）单个MybTFTELOMERE重复结合因子2（TRBF2）在苗期在快速生长的组织中高度表达。TRBF2是与数千个基因的转录起始位点结合的转录阻遏物。TRBF2的突变导致多效性发育缺陷和许多基因的错误表达。TRBF2表现出与体内相分离一致的特征,并在体外形成相分离的缩合物。TRBF2的H1/H5结构域在相分离中起着至关重要的作用,染色质靶向和基因抑制。用拟南芥（拟南芥）的相位分离的内在无序区域替换H1/H5结构域AtSERRATE部分恢复了TRBF2在体外和转基因植物中的基因抑制功能。我们还发现，TRBF2是组蛋白H3Lys27（H3K27me3）在特定基因和全基因组上三甲基化沉积所必需的。我们的发现表明，TRBF2的相分离促进了水稻发育中的基因抑制。
