High impact information on CMT3

• Loss-of-function kryptonite alleles resemble mutants in the DNA methyltransferase gene CHROMOMETHYLASE3 (CMT3), showing loss of cytosine methylation at sites of CpNpG trinucleotides (where N is A, C, G or T) and reactivation of endogenous retrotransposon sequences [1].
• These data suggest that CpNpG DNA methylation is controlled by histone H3 Lys 9 methylation, through interaction of CMT3 with methylated chromatin [1].
• A genetic screen for suppressors of a hypermethylated clark kent mutant identified nine loss-of-function alleles of CHROMOMETHYLASE3 (CMT3), a novel cytosine methyltransferase homolog [2].
• These cmt3 mutants display a wild-type morphology but exhibit decreased CpXpG methylation of the SUP gene and of other sequences throughout the genome [2].
• Thus, CMT3 is a key determinant for non-CG methylation [3].

Biological context of CMT3

• In addition, plants have DNA methylation at CpNpG and CpNpN sites, maintained, in part, by the CHROMOMETHYLASE3 (CMT3) DNA methyltransferase [4].
• Here, we show that Arabidopsis thaliana embryos with loss-of-function mutations in MET1 and CMT3 develop improperly, display altered planes and numbers of cell division, and have reduced viability [4].
• Our results suggest a model in which H3K9 methylation by KYP, and H3K27 methylation by an unknown enzyme provide a combinatorial histone code for the recruitment of CMT3 to silent loci [5].
• CMT3 and KYP targets show similar proximal distributions that correspond to the overall distribution of transposable elements of all types, whereas DRM targets are distributed more distally along the chromosome [6].

Associations of CMT3 with chemical compounds

• The CMT3 pathway depends on histone H3 lysine 9 methylation (H3 mK9) to guide DNA methylation [7].

Other interactions of CMT3

• These signals act in at least three partially intersecting pathways that control the locus-specific patterning of non-CG methylation by the DRM2 and CMT3 methyltransferases [8].
• The sequence of ZMET2 is similar to that of the Arabidopsis chromomethylases CMT1 and CMT3, with C-terminal motifs characteristic of eukaryotic and prokaryotic DNA methyltransferases [9].

Analytical, diagnostic and therapeutic context of CMT3

• Furthermore, using chromatin immunoprecipitation analysis and immunohistolocalization experiments, we found that H3K27 methylation colocalizes with H3K9 methylation at CMT3-controlled loci [5].

References