title: Arabidopsis DEMETER-LIKE proteins DML2 and DML3 are required for appropriate distribution of DNA methylation marks.
abstract: Cytosine DNA methylation is a stable epigenetic mark for maintenance of gene silencing across cellular divisions, but it is a reversible modification. Genetic and biochemical studies have revealed that the Arabidopsis DNA glycosylase domain-containing proteins ROS1 (REPRESSOR OF SILENCING 1) and DME (DEMETER) initiate erasure of 5-methylcytosine through a base excision repair process. The Arabidopsis genome encodes two paralogs of ROS1 and DME, referred to as DEMETER-LIKE proteins DML2 and DML3. We have found that DML2 and DML3 are 5-methylcytosine DNA glycosylases that are expressed in a wide range of plant organs. We analyzed the distribution of methylation marks at two methylated loci in wild-type and dml mutant plants. Mutations in DML2 and/or DML3 lead to hypermethylation of cytosine residues that are unmethylated or weakly methylated in wild-type plants. In contrast, sites that are heavily methylated in wild-type plants are hypomethylated in mutants. These results suggest that DML2 and DML3 are required not only for removing DNA methylation marks from improperly-methylated cytosines, but also for maintenance of high methylation levels in properly targeted sites.
authors.affiliation: Departamento de Genética, Universidad de Córdoba, Edificio Gregor Mendel, Campus de Rabanales s/n, 14071, Córdoba, Spain.
authors.forename: Ana Pilar
authors.initials: AP
authors.lastname: Ortega-Galisteo
authors.forename: Teresa
authors.initials: T
authors.lastname: Morales-Ruiz
authors.forename: Rafael R
authors.initials: RR
authors.lastname: Ariza
authors.forename: Teresa
authors.initials: T
authors.lastname: Roldán-Arjona
mesh_terms: D044503:5-Methylcytosine / Q000032:analysis; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D045647:DNA Glycosylases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D019175:DNA Methylation; D008969:Molecular Sequence Data; D009154:Mutation
chemical_list: D029681:Arabidopsis Proteins; D044503:5-Methylcytosine; C519856:DML2 protein, Arabidopsis; C519857:DML3 protein, Arabidopsis; D045647:DNA Glycosylases