Preferential de novo methylation of cytosine residues in non-CpG sequences by a domains rearranged DNA methyltransferase from tobacco plants.

In plant DNA, cytosines in symmetric CpG and CpNpG (N is A, T, or C) are thought to be methylated by DNA methyltransferases, MET1 and CMT3, respectively. Cytosines in asymmetric CpNpN are also methylated, and genetic analysis has suggested the responsible enzyme to be domains rearranged methyltransferase (DRM). We cloned a tobacco cDNA, encoding a novel protein consisting of 608 amino acids, that resembled DRMs found in maize and Arabidopsis and designated this as NtDRM1.