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The MOM1 complex recruits the RdDM machinery via MORC6 to establish de novo DNA methylation.

ABSTRACT: MOM1 is an Arabidopsis factor 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 unmethylated FWA promoter led to establishment of DNA methylation and FWA silencing. This process was blocked by mutations in components of the Pol V arm of the RdDM machinery, as well as by mutation of MORC6. 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 introduced FWA transgenes 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.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Arabidopsis Thaliana (mouse-ear Cress)

SUBMITTER: Yasi Jami

LAB HEAD: steve Jacobsen

PROVIDER: PXD039991 | Pride | 2023-06-10

REPOSITORIES: Pride

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			Action	DRS
	2019-07-25-140min-200nl-yj-Zheng-Li-Steve-Jacobsen-IP-Col0.raw	Raw
	2019-07-25-140min-200nl-yj-Zheng-Li-Steve-Jacobsen-IP-MOM1-FLAG.raw	Raw
	2019-07-25-140min-200nl-yj-Zheng-Li-Steve-Jacobsen-IP-MOM1-FLAG_in_aipp3-1_mutant-A.raw	Raw
	2019-07-25-140min-200nl-yj-Zheng-Li-Steve-Jacobsen-IP-MOM1-FLAG_in_mom2-2_mutant.raw	Raw
	2019-07-25-140min-200nl-yj-Zheng-Li-Steve-Jacobsen-IP-MOM1-FLAG_in_mom2-2aipp3-1double_mutant.raw	Raw

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The MOM1 complex recruits the RdDM machinery via MORC6 to establish de novo DNA methylation.

Project description:MOM1 is an Arabidopsis factor 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 unmethylated FWA promoter led to establishment of DNA methylation and FWA silencing. This process was blocked by mutations in components of the Pol V arm of the RdDM machinery, as well as by mutation of MORC6. 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 introduced FWA transgenes 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, again colocalized with MORC6. These findings demonstrate a multifaceted role of MOM1 in genome regulation.

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Project description:The Microrchidia (MORC) family of ATPases are required for transposable element (TE) silencing and heterochromatin condensation in plants and animals, and C. elegans MORC-1 has been shown to topologically entrap and condense DNA. In Arabidopsis thaliana, mutation of MORCs has been shown to reactivate silent methylated genes and transposons and to decondense heterochromatic chromocenters, despite only minor changes in the maintenance of DNA methylation. Here we provide the first evidence localizing Arabidopsis MORC proteins to specific regions of chromatin and find that MORC4 and MORC7 are closely co-localized with sites of RNA directed DNA methylation (RdDM). We further show that MORC7, when tethered to DNA by an artificial zinc finger, can facilitate the establishment of RdDM. Finally, we show that MORCs are required for the efficient RdDM mediated establishment of DNA methylation and silencing of a newly integrated FWA transgene, even though morc mutations have no effect on the maintenance of preexisting methylation at the endogenous FWA gene. We propose that MORCs function as a molecular tether in RdDM complexes to reinforce RdDM activity for methylation establishment. These findings have implications for MORC protein function in a variety of other eukaryotic organisms.

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Two components of the RNA-directed DNA methylation pathway associate with MORC6 and silence loci targeted by MORC6 in Arabidopsis

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