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Updated: Jun 21, 2026

Inducible T7 RNA Polymerase-mediated Multigene Expression System, pMGX
Published on: June 27, 2017
Requirement of CHROMOMETHYLASE3 for maintenance of CpXpG methylation
A M Lindroth1, X Cao, J P Jackson
1Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095, USA.
Abstract:
Epigenetic silenced alleles of the Arabidopsis SUPERMAN locus (the clark kent alleles) are associated with dense hypermethylation at noncanonical cytosines (CpXpG and asymmetric sites, where X = A, T, C, or G). 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. These cmt3 mutants display a wild-type morphology but exhibit decreased CpXpG methylation of the SUP gene and of other sequences throughout the genome. They also show reactivated expression of endogenous retrotransposon sequences. These results show that a non-CpG DNA methyltransferase is responsible for maintaining epigenetic gene silencing.
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