Dataset Information

SRA- and SET-domain-containing proteins link RNA polymerase V occupancy to DNA methylation.

ABSTRACT: RNA-directed DNA methylation in Arabidopsis thaliana depends on the upstream synthesis of 24-nucleotide small interfering RNAs (siRNAs) by RNA POLYMERASE IV (Pol IV) and downstream synthesis of non-coding transcripts by Pol V. Pol V transcripts are thought to interact with siRNAs which then recruit DOMAINS REARRANGED METHYLTRANSFERASE 2 (DRM2) to methylate DNA. The SU(VAR)3-9 homologues SUVH2 and SUVH9 act in this downstream step but the mechanism of their action is unknown. Here we show that genome-wide Pol V association with chromatin redundantly requires SUVH2 and SUVH9. Although SUVH2 and SUVH9 resemble histone methyltransferases, a crystal structure reveals that SUVH9 lacks a peptide-substrate binding cleft and lacks a properly formed S-adenosyl methionine (SAM)-binding pocket necessary for normal catalysis, consistent with a lack of methyltransferase activity for these proteins. SUVH2 and SUVH9 both contain SRA (SET- and RING-ASSOCIATED) domains capable of binding methylated DNA, suggesting that they function to recruit Pol V through DNA methylation. Consistent with this model, mutation of DNA METHYLTRANSFERASE 1 (MET1) causes loss of DNA methylation, a nearly complete loss of Pol V at its normal locations, and redistribution of Pol V to sites that become hypermethylated. Furthermore, tethering SUVH9 [corrected] with a zinc finger to an unmethylated site is sufficient to recruit Pol V and establish DNA methylation and gene silencing. These results indicate that Pol V is recruited to DNA methylation through the methyl-DNA binding SUVH2 and SUVH9 proteins, and our mechanistic findings suggest a means for selectively targeting regions of plant genomes for epigenetic silencing.

SUBMITTER: Johnson LM

PROVIDER: S-EPMC3963826 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature

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Publications

SRA- and SET-domain-containing proteins link RNA polymerase V occupancy to DNA methylation.

Johnson Lianna M LM Du Jiamu J Hale Christopher J CJ Bischof Sylvain S Feng Suhua S Chodavarapu Ramakrishna K RK Zhong Xuehua X Marson Giuseppe G Pellegrini Matteo M Segal David J DJ Patel Dinshaw J DJ Jacobsen Steven E SE

Nature 20140122 7490

RNA-directed DNA methylation in Arabidopsis thaliana depends on the upstream synthesis of 24-nucleotide small interfering RNAs (siRNAs) by RNA POLYMERASE IV (Pol IV) and downstream synthesis of non-coding transcripts by Pol V. Pol V transcripts are thought to interact with siRNAs which then recruit DOMAINS REARRANGED METHYLTRANSFERASE 2 (DRM2) to methylate DNA. The SU(VAR)3-9 homologues SUVH2 and SUVH9 act in this downstream step but the mechanism of their action is unknown. Here we show that ge ...[more]

PMID: 24463519

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Project description:RNA-directed DNA methylation (RdDM) in Arabidopsis thaliana depends on the synthesis of non-coding RNAs by nuclear RNA polymerase E (NRPE or Pol V) 1-3, but the mechanism by which Pol V is targeted is unknown. Here we show that genome-wide Pol V association with chromatin redundantly requires the SU(VAR)3-9 homologs, SUVH2 and SUVH9. These proteins resemble histone methyltransferases, however a crystal structure reveals that SUVH9 lacks a peptide-substrate binding cleft and lacks a properly formed S-Adenosyl methionine (SAM) binding pocket necessary for normal catalysis, consistent with a lack of methyltransferase activity for these proteins. SUVH2 and SUVH9 both contain SET- and RING-ASSOCIATED (SRA) domains capable of binding methylated DNA, suggesting that they function to recruit Pol V through DNA methylation. Consistent with this model, mutation of the DNA METHYLTRANSFERASE 1, MET1, causes losses of DNA methylation, a nearly complete loss of Pol V at its normal locations, and redistribution of Pol V to sites that become hypermethylated. By tethering SUVH2 with a zinc finger to an unmethylated epiallele of the homeodomain transcription factor FWA, we demonstrate that SUVH2 is sufficient to both recruit Pol V and establish DNA methylation and gene silencing. Our results suggest that Pol V is recruited to DNA methylation through the methyl-DNA binding SUVH2 and SUVH9 proteins, and our mechanistic findings suggest a means for selectively targeting regions of the plant genome for epigenetic silencing. For wild type plants (ecotype Columbia) and suvh2 suvh9 double mutants whole-genome small RNA (sRNA-seq) and bisulfite sequencing (BS-seq) was performed. For the small RNA sequencing nrpd1 and nrpe1 mutant plants were sequenced in parallel as controls. For the bisulfite sequencing data, the wildtype data and that of the suvh2 and suvh9 single mutants was previously published and is thus not submitted here. In addition, two replicates of whole genome chromatin immunoprecipitation (ChIP-seq) was performed on wild type (ecotype Columbia) plants as a negative control with experimentals consiting of wildtype and suvh2 suvh9 mutant plants carrying a C-terminally epitope tagged (3XFLAG) NRPE1. Whole genome ChIP seq was also performed using a gifted endogenous NRPE1 antibody in a wildtype and met1 mutant background. Whole-genome bisulfite sequencing was also performed on fwa-4 epiallele plants transformed with the wild-type SUVH2 protein-coding construct containing a tethering zinc finger targeted to repeats at the fwa gene. For these transgenic libraries a line carrying a FLAG and fwa targeting zinc-finger tagged KRYPTONITE methyltransferase was bisulfite sequenced as a control (“FLAG-ZF-KYP”).

Dataset Information

SRA- and SET-domain-containing proteins link RNA polymerase V occupancy to DNA methylation.

Publications

SRA- and SET-domain-containing proteins link RNA polymerase V occupancy to DNA methylation.

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