title: AtMBD6, a methyl CpG binding domain protein, maintains gene silencing in Arabidopsis by interacting with RNA binding proteins.
abstract: DNA methylation, mediated by double-stranded RNA, is a conserved epigenetic phenomenon that protects a genome from transposons, silences unwanted genes and has a paramount function in plant or animal development. Methyl CpG binding domain proteins are members of a class of proteins that bind to methylated DNA. The Arabidopsis thaliana genome encodes 13 methyl CpG binding domain (MBD) proteins, but the molecular/biological functions of most of these proteins are still not clear. In the present study, we identified four proteins that interact with AtMBD6. Interestingly, three of them contain RNA binding domains and are co-localized with AtMBD6 in the nucleus. The interacting partners includes AtRPS2C (a 40S ribosomal protein), AtNTF2 (nuclear transport factor 2) and AtAGO4 (Argonoute 4). The fourth protein that physically interacts with AtMBD6 is a histone-modifying enzyme, histone deacetylase 6 (AtHDA6), which is a known component of the RNA-mediated gene silencing system. Analysis of genomic DNA methylation in the atmbd6, atrps2c and atntf2 mutants, using methylation-sensitive PCR detected decreased DNA methylation at miRNA/siRNA producing loci, pseudogenes and other targets of RNA-directed DNA methylation. Our results indicate that AtMBD6 is involved in RNA-mediated gene silencing and it binds to RNA binding proteins like AtRPS2C, AtAGO4 and AtNTF2. AtMBD6 also interacts with histone deacetylase AtHDA6 that might have a role in chromatin condensation at the targets of RdDM.
authors.affiliation: Department of Plant Molecular Biology, University of Delhi, South Campus, New Delhi 110021, India.
authors.forename: Adwaita Prasad
authors.initials: AP
authors.lastname: Parida
authors.forename: Amrapali
authors.initials: A
authors.lastname: Sharma
authors.forename: Arun Kumar
authors.initials: AK
authors.lastname: Sharma
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics; D017360:Arabidopsis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics*; D060565:Argonaute Proteins / Q000235:genetics*; D001665:Binding Sites; D002467:Cell Nucleus / Q000235:genetics; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D020868:Gene Silencing; D006655:Histone Deacetylases / Q000235:genetics*; D026901:Membrane Transport Proteins / Q000235:genetics*; D000070593:Methyl CpG Binding Domain / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics
chemical_list: C471209:AGO4 protein, Arabidopsis; D029681:Arabidopsis Proteins; D060565:Argonaute Proteins; D004268:DNA-Binding Proteins; C519565:MBD6 protein, Arabidopsis; D026901:Membrane Transport Proteins; C510570:NTF2a protein, Arabidopsis; D016601:RNA-Binding Proteins; C089426:RPS2 protein, Arabidopsis; C432452:AT5G63110 protein, Arabidopsis; D006655:Histone Deacetylases