scholarly journals Inhibition of 3' modification of small RNAs in virus-infected plants require spatial and temporal co-expression of small RNAs and viral silencing-suppressor proteins

2008 ◽  
Vol 36 (12) ◽  
pp. 4099-4107 ◽  
Author(s):  
R. Lozsa ◽  
T. Csorba ◽  
L. Lakatos ◽  
J. Burgyan
Keyword(s):  
Small Rnas ◽  
Silencing Suppressor ◽  
Viral Silencing Suppressor

scholarly journals Requirement for Host RNA-Silencing Components and the Virus-Silencing Suppressor when Second-Site Mutations Compensate for Structural Defects in the 3′ Untranslated Region

2015 ◽  
Vol 89 (22) ◽  
pp. 11603-11618 ◽  
Author(s):  
Maitreyi Chattopadhyay ◽  
Vera A. Stupina ◽  
Feng Gao ◽  
Christine R. Szarko ◽  
Micki M. Kuhlmann ◽  
...  
Keyword(s):  
Small Rnas ◽  
Rna Silencing ◽  
Untranslated Region ◽  
Higher Order ◽  
Order Structure ◽  
Silencing Suppressor ◽  
Turnip Crinkle Virus ◽  
Site Mutation ◽  
Primary Mutation ◽  
Positive Strand Rna

ABSTRACTTurnip crinkle virus (TCV) contains a structured 3′ region with hairpins and pseudoknots that form a complex network of noncanonical RNA:RNA interactions supporting higher-order structure critical for translation and replication. We investigated several second-site mutations in the p38 coat protein open reading frame (ORF) that arose in response to a mutation in the asymmetric loop of a critical 3′ untranslated region (UTR) hairpin that disrupts local higher-order structure. All tested second-site mutations improved accumulation of TCV in conjunction with a partial reversion of the primary mutation (TCV-rev1) but had neutral or a negative effect on wild-type (wt) TCV or TCV with the primary mutation. SHAPE (selective 2′-hydroxylacylation analyzed byprimerextension) structure probing indicated that these second-site mutations reside in an RNA domain that includes most of p38 (domain 2), and evidence for RNA:RNA interactions between domain 2 and 3′UTR-containing domain 1 was found. However, second-site mutations were not compensatory in the absence of p38, which is also the TCV silencing suppressor, or indcl-2/dcl4orago1/ago2backgrounds. One second-site mutation reduced silencing suppressor activity of p38 by altering one of two GW motifs that are required for p38 binding to double-stranded RNAs (dsRNAs) and interaction with RNA-induced silencing complex (RISC)-associated AGO1/AGO2. Another second-site mutation substantially reduced accumulation of TCV-rev1 in the absence of p38 or DCL2/DCL4. We suggest that the second-site mutations in the p38 ORF exert positive effects through a similar downstream mechanism, either by enhancing accumulation of beneficial DCL-produced viral small RNAs that positively regulate the accumulation of TCV-rev1 or by affecting the susceptibility of TCV-rev1 to RISC loaded with viral small RNAs.IMPORTANCEGenomes of positive-strand RNA viruses fold into high-order RNA structures. Viruses with mutations in regions critical for translation and replication often acquire second-site mutations that exert a positive compensatory effect through reestablishment of canonical base pairing with the altered region. In this study, two distal second-site mutations that individually arose in response to a primary mutation in a critical 3′ UTR hairpin in the genomic RNA of turnip crinkle virus did not directly interact with the primary mutation. Although different second-site changes had different attributes, compensation was dependent on the production of the viral p38 silencing suppressor and on the presence of silencing-required DCL and AGO proteins. Our results provide an unexpected connection between a 3′ UTR primary-site mutation proposed to disrupt higher-order structure and the RNA-silencing machinery.

scholarly journals Turnip Mosaic Virus Counteracts Selective Autophagy of the Viral Silencing Suppressor HCpro

2017 ◽  
Vol 176 (1) ◽  
pp. 649-662 ◽  
Author(s):  
Anders Hafrén ◽  
Suayib Üstün ◽  
Anton Hochmuth ◽  
Steingrim Svenning ◽  
Terje Johansen ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Turnip Mosaic Virus ◽  
Silencing Suppressor ◽  
Selective Autophagy ◽  
Viral Silencing Suppressor

scholarly journals Expression analysis of host defense responses against the 8K (KDa) cysteine-rich viral silencing suppressor protein in Nicotiana benthamiana

Plant Omics ◽  
2018 ◽  
Vol 11 (02) ◽  
pp. 113-119
Author(s):  
Aminallah Tahmasebi ◽  
◽  
Alireza Afsharifar ◽  
Ahmad Heydari ◽  
Mohammad Mehrabadi ◽  
...  
Keyword(s):  
Expression Analysis ◽  
Host Defense ◽  
Nicotiana Benthamiana ◽  
Defense Responses ◽  
Silencing Suppressor ◽  
Viral Silencing Suppressor

scholarly journals Advanced Engineering of Lipid Metabolism in Nicotiana benthamiana Using a Draft Genome and the V2 Viral Silencing-Suppressor Protein

PLoS ONE ◽  
2012 ◽  
Vol 7 (12) ◽  
pp. e52717 ◽  
Author(s):  
Fatima Naim ◽  
Kenlee Nakasugi ◽  
Ross N. Crowhurst ◽  
Elena Hilario ◽  
Alexander B. Zwart ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Nicotiana Benthamiana ◽  
Draft Genome ◽  
Silencing Suppressor ◽  
Viral Silencing Suppressor

scholarly journals A Structured Viroid RNA Serves as a Substrate for Dicer-Like Cleavage To Produce Biologically Active Small RNAs but Is Resistant to RNA-Induced Silencing Complex-Mediated Degradation

2007 ◽  
Vol 81 (6) ◽  
pp. 2980-2994 ◽  
Author(s):  
Asuka Itaya ◽  
Xuehua Zhong ◽  
Ralf Bundschuh ◽  
Yijun Qi ◽  
Ying Wang ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Small Rnas ◽  
Rna Silencing ◽  
Effective Means ◽  
Critical Role ◽  
Potato Spindle Tuber Viroid ◽  
Biologically Active ◽  
Antiviral Defense ◽  
Silencing Suppressor ◽  
Rna Structures

ABSTRACT RNA silencing is a potent means of antiviral defense in plants and animals. A hallmark of this defense response is the production of 21- to 24-nucleotide viral small RNAs via mechanisms that remain to be fully understood. Many viruses encode suppressors of RNA silencing, and some viral RNAs function directly as silencing suppressors as counterdefense. The occurrence of viroid-specific small RNAs in infected plants suggests that viroids can trigger RNA silencing in a host, raising the question of how these noncoding and unencapsidated RNAs survive cellular RNA-silencing systems. We address this question by characterizing the production of small RNAs of Potato spindle tuber viroid (srPSTVds) and investigating how PSTVd responds to RNA silencing. Our molecular and biochemical studies provide evidence that srPSTVds were derived mostly from the secondary structure of viroid RNAs. Replication of PSTVd was resistant to RNA silencing, although the srPSTVds were biologically active in guiding RNA-induced silencing complex (RISC)-mediated cleavage, as shown with a sensor system. Further analyses showed that without possessing or triggering silencing suppressor activities, the PSTVd secondary structure played a critical role in resistance to RISC-mediated cleavage. These findings support the hypothesis that some infectious RNAs may have evolved specific secondary structures as an effective means to evade RNA silencing in addition to encoding silencing suppressor activities. Our results should have important implications in further studies on RNA-based mechanisms of host-pathogen interactions and the biological constraints that shape the evolution of infectious RNA structures.

scholarly journals Modification of Small RNAs Associated with Suppression of RNA Silencing by Tobamovirus Replicase Protein

2007 ◽  
Vol 81 (19) ◽  
pp. 10379-10388 ◽  
Author(s):  
Hannes Vogler ◽  
Rashid Akbergenov ◽  
Padubidri V. Shivaprasad ◽  
Vy Dang ◽  
Monika Fasler ◽  
...  
Keyword(s):  
Small Rnas ◽  
Rna Silencing ◽  
Fluorescent Protein ◽  
Plant Viruses ◽  
Micro Rna ◽  
Silencing Suppressor ◽  
Small Interfering Rnas ◽  
Suppressor Activity ◽  
Virus Family ◽  
Green Fluorescent

ABSTRACT Plant viruses act as triggers and targets of RNA silencing and have evolved proteins to suppress this plant defense response during infection. Although Tobacco mosaic tobamovirus (TMV) triggers the production of virus-specific small interfering RNAs (siRNAs), this does not lead to efficient silencing of TMV nor is a TMV-green fluorescent protein (GFP) hybrid able to induce silencing of a GFP-transgene in Nicotiana benthamiana, indicating that a TMV silencing suppressor is active and acts downstream of siRNA production. On the other hand, TMV-GFP is unable to spread into cells in which GFP silencing is established, suggesting that the viral silencing suppressor cannot revert silencing that is already established. Although previous evidence indicates that the tobamovirus silencing suppressing activity resides in the viral 126-kDa small replicase subunit, the mechanism of silencing suppression by this virus family is not known. Here, we connect the silencing suppressing activity of this protein with our previous finding that Oilseed rape mosaic tobamovirus infection leads to interference with HEN1-mediated methylation of siRNA and micro-RNA (miRNA). We demonstrate that TMV infection similarly leads to interference with HEN1-mediated methylation of small RNAs and that this interference and the formation of virus-induced disease symptoms are linked to the silencing suppressor activity of the 126-kDa protein. Moreover, we show that also Turnip crinkle virus interferes with the methylation of siRNA but, in contrast to tobamoviruses, not with the methylation of miRNA.

scholarly journals Cucumber Mosaic Virus 2b Protein Subcellular Targets and Interactions: Their Significance to RNA Silencing Suppressor Activity

2010 ◽  
Vol 23 (3) ◽  
pp. 294-303 ◽  
Author(s):  
Inmaculada González ◽  
Llucia Martínez ◽  
Daria V. Rakitina ◽  
Mathew G. Lewsey ◽  
Félix A. Atencio ◽  
...  
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Small Rnas ◽  
Rna Silencing ◽  
Silencing Suppressor ◽  
Suppressor Activity ◽  
Rna Silencing Suppressor ◽  
2B Protein

The RNA silencing suppressor activity of the 2b protein of Cucumber mosaic virus (CMV) has been variously attributed to its nuclear targeting, its interaction with and inhibition of Argonaute 1 (AGO1), or its ability to bind small RNAs in vitro. In addition, the 2b ortholog of Tomato aspermy virus forms aggregates and binds RNAs in vitro. We have further studied the relationships between CMV 2b protein silencing suppressor activity and its subcellular distribution, protein-protein interactions in vivo, and interactions with small interfering RNAs in vitro. To do this, we tagged the protein with fluorescent markers and showed that it retained suppressor activity. We showed that the 2b protein is present in the nucleolus and that it self-interacts and interacts with AGO1 and AGO4 in vivo. Using a battery of mutants, we showed that the putative nuclear localization signals and phosphorylation motif of the 2b protein are not required for self-interaction or for interaction with AGO proteins. The occurrence of neither of these interactions or of nucleolar targeting was sufficient to provide local silencing-suppression activity. In contrast, the ability of the 2b protein to bind small RNAs appears to be indispensable for silencing suppressor function.

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