A Protein Complex Required for Polymerase V Transcripts and RNA- Directed DNA Methylation in Arabidopsis
AuthorsLaw, Julie A.
Johnson, Lianna M.
Vashisht, Ajay A Amar
Wohlschlegel, James A A.
Jacobsen, Steven E.
KAUST DepartmentDesert Agriculture Initiative
Biological and Environmental Sciences and Engineering (BESE) Division
MetadataShow full item record
AbstractDNA methylation is an epigenetic modification associated with gene silencing. In Arabidopsis, DNA methylation is established by DOMAINS REARRANGED METHYLTRANSFERASE 2 (DRM2), which is targeted by small interfering RNAs through a pathway termed RNA-directed DNA methylation (RdDM) [1, 2]. Recently, RdDM was shown to require intergenic noncoding (IGN) transcripts that are dependent on the Pol V polymerase. These transcripts are proposed to function as scaffolds for the recruitment of downstream RdDM proteins, including DRM2, to loci that produce both siRNAs and IGN transcripts . However, the mechanism(s) through which Pol V is targeted to specific genomic loci remains largely unknown. Through affinity purification of two known RdDM components, DEFECTIVE IN RNA-DIRECTED DNA METHYLATION 1 (DRD1)  and DEFECTIVE IN MERISTEM SILENCING 3 (DMS3) [5, 6], we found that they copurify with each other and with a novel protein, RNA-DIRECTED DNA METHYLATION 1 (RDM1), forming a complex we term DDR. We also found that DRD1 copurified with Pol V subunits and that RDM1, like DRD1  and DMS3 , is required for the production of Pol V-dependent transcripts. These results suggest that the DDR complex acts in RdDM at a step upstream of the recruitment or activation of Pol V. © 2010 Elsevier Ltd. All rights reserved.
SponsorsWe thank T. LaGrange for providing the NRPE1 antibody and members of the Jacobsen laboratory for helpful discussion. Jacobsen lab research was supported by U.S. National Institutes of Health (NIH) grant GM60398. I.A. was supported by a postdoctoral fellowship from the Ministerio de Educacion y Ciencia. J.A.L. was supported the NIH National Research Service Award 5F32GM820453. Wohlschlegel lab research was supported by University of California, Los Angeles Jonsson Cancer Center. S.E.J. is an investigator of the Howard Hughes Medical Institute. S.E.J., JAW., J.A.L., and I.A designed the experiments; J.A.L, I.A., L.M.J, and A.A.V. performed the experiments; J.K.Z. provided the ros1-1 rdm1-1 mutant allele and the RDM1 antibody; J.A.L. wrote the paper.
PubMed Central IDPMC2972704
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