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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.

SUBMITTER: Bartee L

PROVIDER: S-EPMC312734 | biostudies-literature | 2001 Jul

REPOSITORIES: biostudies-literature

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Arabidopsis cmt3 chromomethylase mutations block non-CG methylation and silencing of an endogenous gene.

Bartee L L Malagnac F F Bender J J

Genes & development 20010701 14

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 ...[more]

PMID: 11459824

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