Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Shandong Energy Institute, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China.
Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE 68588-0666, USA.
Genes (Basel). 2022 Feb 12;13(2):339. doi: 10.3390/genes13020339.
DNA methylation is an important epigenetic modification required for the specific regulation of gene expression and the maintenance of genome stability in plants and animals. However, the mechanism of DNA demethylation remains largely unknown. Here, we show that two SGS3-like proteins, FACTOR OF DNA DEMETHYLATION 1 (FDDM1) and FDDM2, negatively affect the DNA methylation levels at ROS1-dependend DNA loci in Arabidopsis. FDDM1 binds dsRNAs with 5' overhangs through its XS (rice gene X and SGS3) domain and forms a heterodimer with FDDM2 through its XH (rice gene X Homology) domain. A lack of FDDM1 or FDDM2 increased DNA methylation levels at several ROS1-dependent DNA loci. However, FDDM1 and FDDM2 may not have an additive effect on DNA methylation levels. Moreover, the XS and XH domains are required for the function of FDDM1. Taken together, these results suggest that FDDM1 and FDDM2 act as a heterodimer to positively modulate DNA demethylation. Our finding extends the function of plant-specific SGS3-like proteins.
DNA 甲基化是植物和动物中特定调控基因表达和维持基因组稳定性所必需的重要表观遗传修饰。然而，DNA 去甲基化的机制在很大程度上仍然未知。在这里，我们表明，两个 SGS3 样蛋白，FACTOR OF DNA DEMETHYLATION 1（FDDM1）和 FDDM2，负调控拟南芥中 ROS1 依赖的 DNA 位点的 DNA 甲基化水平。FDDM1 通过其 XS（水稻基因 X 和 SGS3）结构域与 5'突出的 dsRNA 结合，并通过其 XH（水稻基因 X 同源）结构域与 FDDM2 形成异二聚体。缺乏 FDDM1 或 FDDM2 会增加几个 ROS1 依赖的 DNA 位点的 DNA 甲基化水平。然而，FDDM1 和 FDDM2 对 DNA 甲基化水平可能没有累加效应。此外，XS 和 XH 结构域是 FDDM1 功能所必需的。综上所述，这些结果表明 FDDM1 和 FDDM2 作为异二聚体正向调节 DNA 去甲基化。我们的发现扩展了植物特异性 SGS3 样蛋白的功能。
