TY - JOUR T1 - Epigenetic maintenance of DNA methylation after evolutionary loss of the <em>de novo</em> methyltransferase JF - bioRxiv DO - 10.1101/149385 SP - 149385 AU - Sandra Catania AU - Phillip A. Dumesic AU - Caitlin Stoddard AU - Sophie Cooke AU - Jordan Burke AU - Christina A. Cuomo AU - Geeta J. Narlikar AU - Hiten D. Madhani Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/06/13/149385.abstract N2 - After the initial establishment of symmetric cytosine methylation patterns by de novo DNA methyltransferases (DNMTs), maintenance DNMTs mediate epigenetic memory by propagating the initial signal. We find that CG methylation in the yeast Cryptococcus neoformans is dependent on a purely epigenetic mechanism mediated by the single DNMT encoded by the genome, Dnmt5. Purified Dnmt5 is a maintenance methyltransferase that strictly requires a hemimethylated substrate, and methylation lost by removal of Dnmt5 in vivo is not restored by its mitotic or meiotic reintroduction. Phylogenetic analysis reveals that the ancestral species had a second methyltransferase, DnmtX, whose gene was lost between 50 and 150 Mya. Expression of extant DnmtXs in C. neoformans triggers de novo methylation. These data indicate that DNA methylation has been maintained epigenetically by the Dnmt5 system since the ancient loss of the DnmtX de novo enzyme, implying remarkably long-lived epigenetic memory.Single sentence summary Epigenetic information can be inherited over geological timescales ER -