Abstract
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.
Highlights
Introduction published maps and institutional affilThe methylation status of DNA at the 50 position of cytosine (5 mC) plays crucial roles in plants’ developmental regulation and environmental adaptation by affecting gene expression and genome stability [1,2]
We report that the other two SGS3-like proteins, FACTOR OF DNA DEMETHYLATION 1 (FDDM1, AT5G59390) and FDDM2 (AT4G01180), form a complex to participate in DNA demethylation in Arabidopsis
As IDN2 binds 50 overhanging dsRNAs (50 dsRNAs) through its XS and coil-coil domains [15,21], we suspected that FDDM1/FDDM2 might bind 50 dsRNAs
Summary
Introduction published maps and institutional affilThe methylation status of DNA at the 50 position of cytosine (5 mC) plays crucial roles in plants’ developmental regulation and environmental adaptation by affecting gene expression and genome stability [1,2]. The proper level of DNA methylation is dynamically regulated by de novo methylation and the maintenance of methylation and demethylation [1,3,4]. Plant DNA methylation occurs in three cytosine contexts at CG, CHG, and CHH (where H represents A, T, or C) [5,6]. The de novo methylation is established by the RNA-directed DNA methylation (RdDM) pathway, in which DNA is methylated by DOMAINS REARRANGED METHYLTRANSFERASE 2 (DRM2) [7]. DNA methylation is maintained by a multitude of DNA methyltransferases, including METHYLTRANSFERASE 1 (MET1), CHROMOMETHYLASE 3 (CMT3), and CHROMOMETHYLASE 2 (CMT2), in a manner dependent on the cytosine sequence context [8,9,10]. DNA demethylation contributes to methylation levels [11].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
