Maize Chromomethylase Zea methyltransferase2 Is Required for CpNpG Methylation

Our research shows that chromomethylase Zea methyltransferase2 is required for in vivo methylation of CpNpG sequences

Charles M. Papa; Nathan M. Springer; Michael G. Muszynski; Robert Meeley; Shawn M. Kaeppler

2019

Scholarcy highlights

  • Cytosine methylation is a DNA modification that is correlated with gene expression in eukaryotes
  • We have characterized one member of a small gene family of chromomethylases in maize, Zea methyltransferase2. We show that this methyltransferase is required for the methylation of CpNpG sequences
  • The full-length cDNA sequence of Zmet2 was obtained by 3Ј and 5Ј rapid amplification of cDNA ends, and the sequence was analyzed against the GenBank and SWISS-PROT databases
  • ZMET2 and ZMET5 belong to a class of DNA methyltransferases termed chromomethylases
  • The observation that remethylation occurs in normal progeny of zmet2-m1::Mutator transposable element plants indicates either that ZMET2 has in vivo, de novo activity and is responsible for the establishment of CpNpG methylation patterns or that a separate de novo methyltransferase functions only early in development and that Zmet2 is responsible for maintaining these patterns
  • Plants containing a Mu transposable element insertion that disrupts Zmet2 have an ‫ف‬13% reduction in methylation
  • The conservation of chromomethylase function across species as diverse as Arabidopsis and maize suggests that these genes provide a function that offers an evolutionary advantage to the organism
  • DNA gel blot analysis with methylation-sensitive restriction enzymes was conducted on a subset of the plants using the same protocols used for genotyping except that 5 ␮g of DNA was digested

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