title: An SGS3-like protein functions in RNA-directed DNA methylation and transcriptional gene silencing in Arabidopsis.
abstract: RNA-directed DNA methylation (RdDM) is an important epigenetic mechanism for silencing transgenes and endogenous repetitive sequences such as transposons. The RD29A promoter-driven LUCIFERASE transgene and its corresponding endogenous RD29A gene are hypermethylated and silenced in the Arabidopsis DNA demethylase mutant ros1. By screening for second-site suppressors of ros1, we identified the RDM12 locus. The rdm12 mutation releases the silencing of the RD29A-LUC transgene and the endogenous RD29A gene by reducing the promoter DNA methylation. The rdm12 mutation also reduces DNA methylation at endogenous RdDM target loci, including transposons and other repetitive sequences. In addition, the rdm12 mutation affects the levels of small interfering RNAs (siRNAs) from some of the RdDM target loci. RDM12 encodes a protein with XS and coiled-coil domains, and is similar to SGS3, which is a partner protein of RDR6 and can bind to double-stranded RNAs with a 5' overhang, and is required for several post-transcriptional gene silencing pathways. Our results show that RDM12 is a component of the RdDM pathway, and suggest that RdDM may involve double-stranded RNAs with a 5' overhang and the partnering between RDM12 and RDR2.
authors.affiliation: Institute for Integrative Genome Biology and Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA.
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Zheng
authors.forename: Yu
authors.initials: Y
authors.lastname: Xing
authors.forename: Xin-Jian
authors.initials: XJ
authors.lastname: He
authors.forename: Wenbo
authors.initials: W
authors.lastname: Li
authors.forename: Yuanlei
authors.initials: Y
authors.lastname: Hu
authors.forename: Sudesh Kumar
authors.initials: SK
authors.lastname: Yadav
authors.forename: JeeEun
authors.initials: J
authors.lastname: Oh
authors.forename: Jian-Kang
authors.initials: JK
authors.lastname: Zhu
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D019175:DNA Methylation; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D009154:Mutation; D030821:Plants, Genetically Modified / Q000235:genetics; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D019076:Transgenes
chemical_list: D029681:Arabidopsis Proteins; D012330:RNA, Double-Stranded; D018749:RNA, Plant; D016601:RNA-Binding Proteins; C410507:SGS3 protein, Arabidopsis