Interaction with host SGS3 is required for suppression of RNA silencing by tomato yellow leaf curl virus V2 protein

Glick, Efrat; Zrachya, Avi; Levy, Yael; Mett, Anahit; Gidoni, David; Belausov, Eduard; Citovsky, Vitaly; Gafni, Yedidya

doi:10.1073/pnas.0709036105

Cited by 272 publications

(222 citation statements)

References 45 publications

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“…p2 of rice stripe tenuivirus and p6 of rice yellow stunt rhabdovirus interacted with SGS3 and RDR6, respectively (Du et al, 2011;Guo et al, 2013). V2 encoded by tomato yellow leaf curl geminivirus also interacted with and colocalized with SGS3 (Glick et al, 2008). However, in another study, V2 interacted with dsRNA to prevent SGS3 from accessing its substrate (Fukunaga and Doudna, 2009).…”

Section: Discussionmentioning

confidence: 94%

In Planta Recognition of a Double-Stranded RNA Synthesis Protein Complex by a Potexviral RNA Silencing Suppressor

et al. 2014

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RNA silencing plays an important antiviral role in plants and invertebrates. To counteract antiviral RNA silencing, most plant viruses have evolved viral suppressors of RNA silencing (VSRs). TRIPLE GENE BLOCK PROTEIN1 (TGBp1) of potexviruses is a well-characterized VSR, but the detailed mechanism by which it suppresses RNA silencing remains unclear. We demonstrate that transgenic expression of TGBp1 of plantago asiatica mosaic virus (PlAMV) induced developmental abnormalities in Arabidopsis thaliana similar to those observed in mutants of SUPPRESSOR OF GENE SILENCING3 (SGS3) and RNA-DEPENDENT RNA POLYMERASE6 (RDR6) required for the trans-acting small interfering RNA synthesis pathway. PlAMV-TGBp1 inhibits SGS3/ RDR6-dependent double-stranded RNA synthesis in the trans-acting small interfering RNA pathway. TGBp1 interacts with SGS3 and RDR6 and coaggregates with SGS3/RDR6 bodies, which are normally dispersed in the cytoplasm. In addition, TGBp1 forms homooligomers, whose formation coincides with TGBp1 aggregation with SGS3/RDR6 bodies. These results reveal the detailed molecular function of TGBp1 as a VSR and shed new light on the SGS3/RDR6-dependent double-stranded RNA synthesis pathway as another general target of VSRs.

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Section: Discussionmentioning

confidence: 94%

In Planta Recognition of a Double-Stranded RNA Synthesis Protein Complex by a Potexviral RNA Silencing Suppressor

et al. 2014

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“…We also found that IDN2 was likely to act in a step downstream of initial siRNA biogenesis. The XS domain is conserved throughout the plant kingdom, and XS-domain-containing proteins are involved in a wide range of processes such as viral defense (8) and stress response (9).…”

mentioning

confidence: 99%

INVOLVED IN DE NOVO 2-containing complex involved in RNA-directed DNA methylation in Arabidopsis

Ausín

Greenberg

Simanshu

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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At least three pathways control maintenance of DNA cytosine methylation in Arabidopsis thaliana. However, the RNA-directed DNA methylation (RdDM) pathway is solely responsible for establishment of this silencing mark. We previously described INVOLVED IN DE NOVO 2 (IDN2) as being an RNA-binding RdDM component that is required for DNA methylation establishment. In this study, we describe the discovery of two partially redundant proteins that are paralogous to IDN2 and that form a stable complex with IDN2 in vivo. Null mutations in both genes, termed IDN2-LIKE 1 and IDN2-LIKE 2 (IDNL1 and IDNL2), result in a phenotype that mirrors, but does not further enhance, the idn2 mutant phenotype. Genetic analysis suggests that this complex acts in a step in the downstream portion of the RdDM pathway. We also have performed structural analysis showing that the IDN2 XS domain adopts an RNA recognition motif (RRM) fold. Finally, genome-wide DNA methylation and expression analysis confirms the placement of the IDN proteins in an RdDM pathway that affects DNA methylation and transcriptional control at many sites in the genome. Results from this study identify and describe two unique components of the RdDM machinery, adding to our understanding of DNA methylation control in the Arabidopsis genome.genomics | mass spectrometry | siRNAs | epigenetics D NA methylation is a stable epigenetic mark that is associated with the repression of genes and transposable elements. In Arabidopsis thaliana, maintenance of DNA methylation at silent loci is carried out by at least three methyltransferases: METH-YLTRANSFERASE 1 (MET1), CHROMOMETHYLTRANS-FERASE 3 (CMT3), and DOMAINS REARRANGED METHYLTRANSFERASE 2 (DRM2). However, DRM2 is solely responsible for establishment of DNA methylation-or de novo methylation-of silent elements (1). DRM2 is guided to chromatin by small interfering RNAs (siRNAs) in a process known as RNAdirected DNA methylation (RdDM) (2). It has been proposed that RdDM also requires intergenic noncoding (IGN) transcripts that are synthesized by RNA Polymerase V (Pol V). These transcripts likely serve as platforms for the recruitment of siRNA-loaded ARGONAUTE 4 (AGO4) to methylated loci (3, 4).Recently, we discovered the requirement of INVOLVED IN DE NOVO 2 (IDN2) for RdDM from a forward genetic screen (5). Alleles of this same gene were later reported from another screen for DNA methylation mutants (6). We previously demonstrated that IDN2 binds to double-stranded RNA through its XS domain, which is also observed in the XS-domain-containing protein SUPPRESSOR OF GENE SILENCING 3 (SGS3) (7). We also found that IDN2 was likely to act in a step downstream of initial siRNA biogenesis. The XS domain is conserved throughout the plant kingdom, and XS-domain-containing proteins are involved in a wide range of processes such as viral defense (8) and stress response (9).To gain a better understanding of the in vivo role of IDN2, we performed affinity purifications from complementing transgenic lines expressing epitope-tagged full-length I...

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“…SGS3 was shown to be required for CaLCuV virus induced VIGS of endogenous genes and was further suggested to be involved in the antiviral response against DNA viruses (Muangsan et al 2004). This is supported by the fact that Tomato yellow leaf curl virus (TYLCV) encodes a silencing suppressor to compromise SGS3 activity (Glick et al 2008). SDE5 is an RNA trafficking protein homologue of human mRNA export factor.…”

Section: Amplification Of Silencingmentioning

confidence: 85%

Antiviral Silencing and Suppression of Gene Silencing in Plants

Csorba

Burgyán

2016

Current Research Topics in Plant Virology

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RNA silencing is an evolutionary conserved sequence-specific gene inactivation mechanism that contributes to the control of development, maintains heterochromatin, acts in stress responses, DNA repair and defends against invading nucleic acids like transposons and viruses. In plants RNA silencing functions as one of the main immune systems. RNA silencing process involves the small RNAs and trans factor components like Dicers, Argonautes and RNA-dependent RNA polymerases. To deal with host antiviral silencing responses viruses evolved mechanisms to avoid or counteract this, most notably through expression of viral suppressors of RNA silencing. Due to the overlap between endogenous and antiviral silencing pathways while blocking antiviral pathways viruses also impact endogenous silencing processes. Here we provide an overview of antiviral silencing pathway, host factors implicated in it and the crosstalk between antiviral and endogenous branches of silencing. We summarize the current status of knowledge about the viral counter-defense strategies acting at various steps during virus infection in plants with the focus on representative, well studied silencing suppressor proteins. Finally we discuss future challenges of the antiviral silencing and counter-defense research field.

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Interaction with host SGS3 is required for suppression of RNA silencing by tomato yellow leaf curl virus V2 protein

Cited by 272 publications

References 45 publications

In Planta Recognition of a Double-Stranded RNA Synthesis Protein Complex by a Potexviral RNA Silencing Suppressor

In Planta Recognition of a Double-Stranded RNA Synthesis Protein Complex by a Potexviral RNA Silencing Suppressor

INVOLVED IN DE NOVO 2-containing complex involved in RNA-directed DNA methylation in Arabidopsis

Antiviral Silencing and Suppression of Gene Silencing in Plants

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