scholarly journals Cymbidium Ringspot Virus Harnesses RNA Silencing To Control the Accumulation of Virus Parasite Satellite RNA

2008 ◽  
Vol 82 (23) ◽  
pp. 11851-11858 ◽  
Author(s):  
Vitantonio Pantaleo ◽  
József Burgyán
Keyword(s):  
Rna Silencing ◽  
Sequence Similarity ◽  
Helper Virus ◽  
Ringspot Virus ◽  
Silencing Suppressor ◽  
Short Interfering Rna ◽  
Satellite Rna ◽  
The Cost ◽  
Interfering Rna ◽  
Rna Replicon

ABSTRACT Cymbidium ringspot virus (CymRSV) satellite RNA (satRNA) is a parasitic subviral RNA replicon that replicates and accumulates at the cost of its helper virus. This 621-nucleotide (nt) satRNA species has no sequence similarity to the helper virus, except for a 51-nt-long region termed the helper-satellite homology (HSH) region, which is essential for satRNA replication. We show that the accumulation of satRNA strongly depends on temperature and on the presence of the helper virus p19 silencing suppressor protein, suggesting that RNA silencing plays a crucial role in satRNA accumulation. We also demonstrate that another member of the Tombusvirus genus, Carnation Italian ringspot virus (CIRV), supports satRNA accumulation at a higher level than CymRSV. Our results suggest that short interfering RNA (siRNA) derived from CymRSV targets satRNA more efficiently than siRNA from CIRV, possibly because of the higher sequence similarity between the HSH regions of the helper and CIRV satRNAs. RNA silencing sensor RNA carrying the putative satRNA target site in the HSH region was efficiently cleaved when transiently expressed in CymRSV-infected plants but not in CIRV-infected plants. Strikingly, replacing the CymRSV HSH box2 sequence with that of CIRV restores satRNA accumulation both at 24°C and in the absence of the p19 suppressor protein. These findings demonstrate the extraordinary adaptation of this virus to its host in terms of harnessing the antiviral silencing response of the plant to control the virus parasite satRNA.

scholarly journals Cucurbit chlorotic yellows virus p22 suppressor of RNA silencing binds single-, double-stranded long and short interfering RNA molecules in vitro

2020 ◽  
Vol 279 ◽  
pp. 197887
Author(s):  
Ferran Salavert ◽  
José Antonio Navarro ◽  
Carolyn A. Owen ◽  
Souheyla Khechmar ◽  
Vicente Pallás ◽  
...  
Keyword(s):  
Rna Silencing ◽  
Short Interfering Rna ◽  
Rna Molecules ◽  
Interfering Rna ◽  
Suppressor Of Rna Silencing ◽  
Cucurbit Chlorotic Yellows Virus

scholarly journals Hibiscus chlorotic ringspot virus coat protein inhibits trans-acting small interfering RNA biogenesis in Arabidopsis

2008 ◽  
Vol 89 (9) ◽  
pp. 2349-2358 ◽  
Author(s):  
Chunying Meng ◽  
Jun Chen ◽  
Shou-wei Ding ◽  
Jinrong Peng ◽  
Sek-Man Wong
Keyword(s):  
Coat Protein ◽  
Gene Silencing ◽  
Rna Silencing ◽  
Small Interfering Rna ◽  
Fluorescent Protein ◽  
Cauliflower Mosaic Virus ◽  
Ringspot Virus ◽  
Pcr Analysis ◽  
Transcriptional Gene Silencing ◽  
Interfering Rna

Many plant and animal viruses have evolved suppressor proteins to block host RNA silencing at various stages of the RNA silencing pathways. Hibiscus chlorotic ringspot virus (HCRSV) coat protein (CP) is capable of suppressing the transiently expressed sense-RNA-induced post-transcriptional gene silencing (PTGS) in Nicotiana benthamiana. Here, constitutively expressed HCRSV CP from transgenic Arabidopsis was found to be able to rescue expression of the silenced GUS transgene. The HCRSV CP-transgenic Arabidopsis (line CP6) displayed several developmental abnormalities: elongated, downwardly curled leaves and a lack of coordination between stamen and carpel, resulting in reduced seed set. These abnormalities are similar to those observed in mutations of the genes of Arabidopsis RNA-dependent polymerase 6 (rdr6), suppressor of gene silencing 3 (sgs3), ZIPPY (zip) and dicer-like 4 (dcl4). The accumulation of microRNA (miRNA) miR173 remained stable; however, the downstream trans-acting small interfering RNA (ta-siRNA) siR255 was greatly reduced. Real-time PCR analysis showed that expression of the ta-siRNA-targeted At4g29770, At5g18040, PPR and ARF3 genes increased significantly, especially in the inflorescences. Genetic crossing of CP6 with an amplicon-silenced line (containing a potato virus X–green fluorescent protein transgene under the control of the 35S cauliflower mosaic virus promoter) suggested that HCRSV CP probably interfered with gene silencing at a step after RDR6. The reduced accumulation of ta-siRNA might result from the interference of HCRSV CP with Dicer-like protein(s), responsible for the generation of dsRNA in ta-siRNA biogenesis.

scholarly journals Two classes of short interfering RNA in RNA  silencing

2015 ◽  
Vol 34 (20) ◽  
pp. 2590-2590 ◽  
Author(s):  
Andrew Hamilton ◽  
Olivier Voinnet ◽  
Louise Chappell ◽  
David Baulcombe
Keyword(s):  
Rna Silencing ◽  
Short Interfering Rna ◽  
Interfering Rna

scholarly journals cis and trans Requirements for Rolling Circle Replication of a Satellite RNA

2004 ◽  
Vol 78 (6) ◽  
pp. 3072-3082 ◽  
Author(s):  
Sang Ik Song ◽  
W. Allen Miller
Keyword(s):  
Sequence Similarity ◽  
Hammerhead Ribozyme ◽  
Helper Virus ◽  
Yellow Dwarf ◽  
Rolling Circle Replication ◽  
Satellite Rna ◽  
Rolling Circle ◽  
Satellite Rnas ◽  
Rna Accumulation

ABSTRACT Satellite RNAs usurp the replication machinery of their helper viruses, even though they bear little or no sequence similarity to the helper virus RNA. In Cereal yellow dwarf polerovirus serotype RPV (CYDV-RPV), the 322-nucleotide satellite RNA (satRPV RNA) accumulates to high levels in the presence of the CYDV-RPV helper virus. Rolling circle replication generates multimeric satRPV RNAs that self-cleave via a double-hammerhead ribozyme structure. Alternative folding inhibits formation of a hammerhead in monomeric satRPV RNA. Here we determine helper virus requirements and the effects of mutations and deletions in satRPV RNA on its replication in oat cells. Using in vivo selection of a satRPV RNA pool randomized at specific bases, we found that disruption of the base pairing necessary to form the non-self-cleaving conformation reduced satRPV RNA accumulation. Unlike other satellite RNAs, both the plus and minus strands proved to be equally infectious. Accordingly, very similar essential replication structures were identified in each strand. A different region is required only for encapsidation. The CYDV-RPV RNA-dependent RNA polymerase (open reading frames 1 and 2), when expressed from the nonhelper Barley yellow dwarf luteovirus, was capable of replicating satRPV RNA. Thus, the helper virus's polymerase is the sole determinant of the ability of a virus to replicate a rolling circle satellite RNA. We present a framework for functional domains in satRPV RNA with three types of function: (i) conformational control elements comprising an RNA switch, (ii) self-functional elements (hammerhead ribozymes), and (iii) cis-acting elements that interact with viral proteins.

scholarly journals The p122 Subunit of Tobacco Mosaic Virus Replicase Is a Potent Silencing Suppressor and Compromises both Small Interfering RNA- and MicroRNA-Mediated Pathways

2007 ◽  
Vol 81 (21) ◽  
pp. 11768-11780 ◽  
Author(s):  
Tibor Csorba ◽  
Aurelie Bovi ◽  
Tamás Dalmay ◽  
József Burgyán
Keyword(s):  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Nuclear Export ◽  
Rna Silencing ◽  
Plant Viruses ◽  
Silencing Suppressor ◽  
Small Interfering Rnas ◽  
In Planta ◽  
Interfering Rna

ABSTRACT One of the functions of RNA silencing in plants is to defend against molecular parasites, such as viruses, retrotransposons, and transgenes. Plant viruses are inducers, as well as targets, of RNA silencing-based antiviral defense. Replication intermediates or folded viral RNAs activate RNA silencing, generating small interfering RNAs (siRNAs), which are the key players in the antiviral response. Viruses are able to counteract RNA silencing by expressing silencing-suppressor proteins. It has been shown that many of the identified silencing-suppressor proteins bind long double-stranded RNA or siRNAs and thereby prevent assembly of the silencing effector complexes. In this study, we show that the 122-kDa replicase subunit (p122) of crucifer-infecting Tobacco mosaic virus (cr-TMV) is a potent silencing-suppressor protein. We found that the p122 protein preferentially binds to double-stranded 21-nucleotide (nt) siRNA and microRNA (miRNA) intermediates with 2-nt 3′ overhangs inhibiting the incorporation of siRNA and miRNA into silencing-related complexes (e.g., RNA-induced silencing complex [RISC]) both in vitro and in planta but cannot interfere with previously programmed RISCs. In addition, our results also suggest that the virus infection and/or sequestration of the siRNA and miRNA molecules by p122 enhances miRNA accumulation despite preventing its methylation. However, the p122 silencing suppressor does not prevent the methylation of certain miRNAs in hst-15 mutants, in which the nuclear export of miRNAs is compromised.

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