An antiviral RISC isolated from Tobacco rattle virus-infected plants

Ciomperlik, Jessica J.; Omarov, Rustem T.; Scholthof, Karen‐Beth G.

doi:10.1016/j.virol.2010.12.018

Cited by 14 publications

(11 citation statements)

References 40 publications

(68 reference statements)

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“…In support of this, we and others have provided direct evidence for a vRISC in Tombusvirus-infected plants, using TBSV P19 mutants and various biochemical approaches (Omarov et al, 2007;Pantaleo et al, 2007). More recently we isolated a sequence-specific vRISC from monocot and dicot plants infected with other viruses (Ciomperlik et al, 2011). Thus, plants have conserved the ability to mount an antiviral defense by activating a discrete and virus sequence-specific vRISC that can be isolated and analyzed in vitro.…”

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confidence: 55%

Identification of an ARGONAUTE for Antiviral RNA Silencing in Nicotiana benthamiana

et al. 2011

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ARGONAUTE proteins (AGOs) are known to be key components of the RNA silencing mechanism in eukaryotes that, among other functions, serves to protect against viral invaders. Higher plants encode at least 10 individual AGOs yet the role played by many in RNA silencing-related antiviral defense is largely unknown, except for reports that AGO1, AGO2, and AGO7 play an antiviral role in Arabidopsis (Arabidopsis thaliana). In the plant virus model host Nicotiana benthamiana, Tomato bushy stunt virus (TBSV) P19 suppressor mutants are very susceptible to RNA silencing. Here, we report that a N. benthamiana AGO (NbAGO) with similarity to Arabidopsis AGO2, is involved in antiviral defense against TBSV. The activity of this NbAGO2 is shown to be directly associated with anti-TBSV RNA silencing, while its inactivation does not influence silencing of transiently expressed transgenes. Thus, the role of NbAGO2 might be primarily for antiviral defense.

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confidence: 55%

Identification of an ARGONAUTE for Antiviral RNA Silencing in Nicotiana benthamiana

et al. 2011

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“…RISC fractions isolated from TRV-infected N . benthamiana plants also distributed in two different peaks [ 13 ], while no fractions isolated from wild type tobamovirus infected N . benthamiana plant contained RISC-activity.…”

Section: Discussionmentioning

confidence: 99%

Antiviral RISC mainly targets viral mRNA but not genomic RNA of tospovirus

et al. 2021

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Antiviral RNA silencing/interference (RNAi) of negative-strand (-) RNA plant viruses (NSVs) has been studied less than for single-stranded, positive-sense (+)RNA plant viruses. From the latter, genomic and subgenomic mRNA molecules are targeted by RNAi. However, genomic RNA strands from plant NSVs are generally wrapped tightly within viral nucleocapsid (N) protein to form ribonucleoproteins (RNPs), the core unit for viral replication, transcription and movement. In this study, the targeting of the NSV tospoviral genomic RNA and mRNA molecules by antiviral RNA-induced silencing complexes (RISC) was investigated, in vitro and in planta. RISC fractions isolated from tospovirus-infected N. benthamiana plants specifically cleaved naked, purified tospoviral genomic RNAs in vitro, but not genomic RNAs complexed with viral N protein. In planta RISC complexes, activated by a tobacco rattle virus (TRV) carrying tospovirus NSs or Gn gene fragments, mainly targeted the corresponding viral mRNAs and hardly genomic (viral and viral-complementary strands) RNA assembled into RNPs. In contrast, for the (+)ssRNA cucumber mosaic virus (CMV), RISC complexes, activated by TRV carrying CMV 2a or 2b gene fragments, targeted CMV genomic RNA. Altogether, the results indicated that antiviral RNAi primarily targets tospoviral mRNAs whilst their genomic RNA is well protected in RNPs against RISC-mediated cleavage. Considering the important role of RNPs in the replication cycle of all NSVs, the findings made in this study are likely applicable to all viruses belonging to this group.

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“…AGO proteins target endogenous transcripts to regulate plant development and innate immunity [ 2 , 56 ], which may indirectly affect susceptibility to viruses. It is likely, however, that at least some AGO proteins with an antiviral role are programmed with virus-derived siRNA to directly target viral RNA [ 8 , 10 , 57 , 58 ]. The genetic analysis described here revealed several AGO proteins that participate in modular fashion during anti-TuMV defense ( Fig.…”

Section: Discussionmentioning

confidence: 99%

Roles and Programming of Arabidopsis ARGONAUTE Proteins during Turnip Mosaic Virus Infection

et al. 2015

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In eukaryotes, ARGONAUTE proteins (AGOs) associate with microRNAs (miRNAs), short interfering RNAs (siRNAs), and other classes of small RNAs to regulate target RNA or target loci. Viral infection in plants induces a potent and highly specific antiviral RNA silencing response characterized by the formation of virus-derived siRNAs. Arabidopsis thaliana has ten AGO genes of which AGO1, AGO2, and AGO7 have been shown to play roles in antiviral defense. A genetic analysis was used to identify and characterize the roles of AGO proteins in antiviral defense against Turnip mosaic virus (TuMV) in Arabidopsis. AGO1, AGO2 and AGO10 promoted anti-TuMV defense in a modular way in various organs, with AGO2 providing a prominent antiviral role in leaves. AGO5, AGO7 and AGO10 had minor effects in leaves. AGO1 and AGO10 had overlapping antiviral functions in inflorescence tissues after systemic movement of the virus, although the roles of AGO1 and AGO10 accounted for only a minor amount of the overall antiviral activity. By combining AGO protein immunoprecipitation with high-throughput sequencing of associated small RNAs, AGO2, AGO10, and to a lesser extent AGO1 were shown to associate with siRNAs derived from silencing suppressor (HC-Pro)-deficient TuMV-AS9, but not with siRNAs derived from wild-type TuMV. Co-immunoprecipitation and small RNA sequencing revealed that viral siRNAs broadly associated with wild-type HC-Pro during TuMV infection. These results support the hypothesis that suppression of antiviral silencing during TuMV infection, at least in part, occurs through sequestration of virus-derived siRNAs away from antiviral AGO proteins by HC-Pro. These findings indicate that distinct AGO proteins function as antiviral modules, and provide a molecular explanation for the silencing suppressor activity of HC-Pro.

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An antiviral RISC isolated from Tobacco rattle virus-infected plants

Cited by 14 publications

References 40 publications

Identification of an ARGONAUTE for Antiviral RNA Silencing in Nicotiana benthamiana

Identification of an ARGONAUTE for Antiviral RNA Silencing in Nicotiana benthamiana

Antiviral RISC mainly targets viral mRNA but not genomic RNA of tospovirus

Roles and Programming of Arabidopsis ARGONAUTE Proteins during Turnip Mosaic Virus Infection

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