title: Arabidopsis cmt3 chromomethylase mutations block non-CG methylation and silencing of an endogenous gene.
abstract: Plants maintain cytosine methylation at CG and non-CG residues to control gene expression and genome stability. In a screen for Arabidopsis mutants that alter methylation and silencing of a densely methylated endogenous reporter gene, we recovered 11 loss-of-function alleles in the CMT3 chromomethylase gene. The cmt3 mutants displayed enhanced expression and reduced methylation of the reporter, particularly at non-CG cytosines. CNG methylation was also reduced at repetitive centromeric sequences. Thus, CMT3 is a key determinant for non-CG methylation. The lack of CMT homologs in animal genomes could account for the observation that in contrast to plants, animals maintain primarily CG methylation.
authors.affiliation: Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA.
authors.forename: L
authors.initials: L
authors.lastname: Bartee
authors.forename: F
authors.initials: F
authors.lastname: Malagnac
authors.forename: J
authors.initials: J
authors.lastname: Bender
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000235:genetics*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins; D019175:DNA Methylation; D015257:DNA-Cytosine Methylases / Q000235:genetics*; D020868:Gene Silencing; D017930:Genes, Reporter; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D029681:Arabidopsis Proteins; D015257:DNA-Cytosine Methylases; C429766:CMT3 protein, Arabidopsis; D019747:Aldose-Ketose Isomerases; C029865:phosphoribosylanthranilate isomerase