Open AccessMolecular Mechanism of Action of Plant DRM De Novo DNA Methyltransferases
Author(s) -
Xuehua Zhong,
Jiamu Du,
Christopher J. Hale,
Javier GallegoBartolomé,
Suhua Feng,
Ajay A. Vashisht,
Joanne Chory,
James A. Wohlschlegel,
Dinshaw J. Patel,
Steven E. Jacobsen
Publication year - 2014
Publication title -
cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 26.304
H-Index - 776
eISSN - 1097-4172
pISSN - 0092-8674
DOI - 10.1016/j.cell.2014.03.056
Subject(s) - biology , rna directed dna methylation , methyltransferase , rna , methylation , dna methylation , small interfering rna , dna , argonaute , epigenetics , dna methyltransferase , microbiology and biotechnology , base pair , trans acting sirna , genetics , long non coding rna , gene , gene expression
DNA methylation is a conserved epigenetic gene-regulation mechanism. DOMAINS REARRANGED METHYLTRANSFERASE (DRM) is a key de novo methyltransferase in plants, but how DRM acts mechanistically is poorly understood. Here, we report the crystal structure of the methyltransferase domain of tobacco DRM (NtDRM) and reveal a molecular basis for its rearranged structure. NtDRM forms a functional homodimer critical for catalytic activity. We also show that Arabidopsis DRM2 exists in complex with the small interfering RNA (siRNA) effector ARGONAUTE4 (AGO4) and preferentially methylates one DNA strand, likely the strand acting as the template for RNA polymerase V-mediated noncoding RNA transcripts. This strand-biased DNA methylation is also positively correlated with strand-biased siRNA accumulation. These data suggest a model in which DRM2 is guided to target loci by AGO4-siRNA and involves base-pairing of associated siRNAs with nascent RNA transcripts.
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