The MOM1 complex recruits the RdDM machinery via MORC6 to establishde novoDNA methylation

Abstract

AbstractMOM1 is anArabidopsisfactor previously shown to mediate transcriptional silencing independent of major DNA methylation changes. Here we found that MOM1 localizes with sites of RNA-directed DNA methylation (RdDM). Tethering MOM1 with artificial zinc finger to unmethylatedFWApromoter led to establishment of DNA methylation andFWAsilencing. This process was blocked by mutations in components of the Pol V arm of the RdDM machinery, as well as by mutation ofMORC6. We found that at some endogenous RdDM sites, MOM1 is required to maintain DNA methylation and a closed chromatin state. In addition, efficient silencing of newly introducedFWAtransgenes was impaired by mutation of MOM1 or mutation of genes encoding the MOM1 interacting PIAL1/2 proteins. In addition to RdDM sites, we identified a group of MOM1 peaks at active chromatin near genes that colocalized with MORC6. These findings demonstrate a multifaceted role of MOM1 in genome regulation.