Citrus tristeza virus p23 may suppress systemic silencing but is not related to the kind of viral syndrome

Costa, Ângela A.; Marques, Natália; Nolasco, Gustavo

doi:10.1016/j.pmpp.2014.07.002

Cited by 6 publications

(4 citation statements)

References 41 publications

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“…However, for other viruses the silencing suppressor protein has not been crystallized yet, and hence in silico prediction was used to determine their structure. Costa et al [74] found that p23, one of the three silencing suppressor proteins of Citrus tristeza virus (CTV), was able to transiently suppress the local but not the short-range silencing. They predicted a 3D model structure of the p23 protein using I-TASSER modeler, which showed differences within the Zn-finger region, between isolates.…”

Section: Discussionmentioning

confidence: 99%

Identification and localization of Tospovirus genus-wide conserved residues in 3D models of the nucleocapsid and the silencing suppressor proteins

Olaya

Adhikari

Raikhy

et al. 2019

Virol J

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BackgroundTospoviruses (genus Tospovirus, family Peribunyaviridae, order Bunyavirales) cause significant losses to a wide range of agronomic and horticultural crops worldwide. Identification and characterization of specific sequences and motifs that are critical for virus infection and pathogenicity could provide useful insights and targets for engineering virus resistance that is potentially both broad spectrum and durable. Tomato spotted wilt virus (TSWV), the most prolific member of the group, was used to better understand the structure-function relationships of the nucleocapsid gene (N), and the silencing suppressor gene (NSs), coded by the TSWV small RNA.MethodsUsing a global collection of orthotospoviral sequences, several amino acids that were conserved across the genus and the potential location of these conserved amino acid motifs in these proteins was determined. We used state of the art 3D modeling algorithms, MULTICOM-CLUSTER, MULTICOM-CONSTRUCT, MULTICOM-NOVEL, I-TASSER, ROSETTA and CONFOLD to predict the secondary and tertiary structures of the N and the NSs proteins.ResultsWe identified nine amino acid residues in the N protein among 31 known tospoviral species, and ten amino acid residues in NSs protein among 27 tospoviral species that were conserved across the genus. For the N protein, all three algorithms gave nearly identical tertiary models. While the conserved residues were distributed throughout the protein on a linear scale, at the tertiary level, three residues were consistently located in the coil in all the models. For NSs protein models, there was no agreement among the three algorithms. However, with respect to the localization of the conserved motifs, G18 was consistently located in coil, while H115 was localized in the coil in three models.ConclusionsThis is the first report of predicting the 3D structure of any tospoviral NSs protein and revealed a consistent location for two of the ten conserved residues. The modelers used gave accurate prediction for N protein allowing the localization of the conserved residues. Results form the basis for further work on the structure-function relationships of tospoviral proteins and could be useful in developing novel virus control strategies targeting the conserved residues.Electronic supplementary materialThe online version of this article (10.1186/s12985-018-1106-4) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Identification and localization of Tospovirus genus-wide conserved residues in 3D models of the nucleocapsid and the silencing suppressor proteins

Olaya

Adhikari

Raikhy

et al. 2019

Virol J

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“…qPCR was performed using Xpert Fast SYBR 2X mastermix (GRiSP, Lda., Porto, Portugal) with ROX according to the manufacturer’s specifications with the addition of 2 μL of the RT reaction and 0.4 μΜ of each primer. Primer pairs GFP-ER Taq-F/GFP-ER Taq-R [ 20 ] and L23-F/L23-R [ 21 ] were used for the detection of GFP and L23 internal control, respectively. All qPCRs were performed in a StepOnePlus real-time PCR system (Applied Biosystems, Waltham, MA, USA) using three technical replicates for each sample in the following thermocycling protocol: initial denaturation at 95 °C for 5 min followed by 40 cycles segmented at 95 °C for 10 s and 60 °C for 20 s with a final melting curve stage of 95 °C for 15 s, 60 °C for 1 min, and a +0.3 °C ramp up to 95 °C for 15 s. Relative expression levels of GFP mRNA were calculated according to the 2 −ΔΔCq method.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of the RNA Silencing Suppression Activity of Three Cherry Virus F-Encoded Proteins

Lotos,

Katsiani,

Katis

et al. 2024

Plants

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Cherry virus F (CVF) is a newly emerged sweet cherry virus. CVF has been identified in a small number of countries and it has not been associated with discrete symptomatology. RNA silencing is a natural defense mechanism of plants against invaders that degrades viral RNA in a sequence-specific manner. As a counter-defense, plant viruses encode one or more RNA silencing suppressors (RSSs) interfering with the silencing pathway via several mechanisms. To identify putative RSSs, the three proteins (MP, CPL, CPS) encoded by the RNA2 of CVF were selected and separately cloned into the binary vector pART27. The clones were used for transient expression experiments in Nicotiana benthamiana leaves, using co-agroinfiltration with a GFP-expressing vector. In both CPL and CPS, a rapid decrease in fluorescence was recorded, comparable to the negative control, whereas the MP of CVF retained the GFP’s fluorescence for a few days longer even though this was observed in a small number of infiltrated leaves. Further experiments have shown that the protein was not able to inhibit the cell-to-cell spread of the silencing signal; however, a putative interference with systemic silencing was recorded especially when the induction was carried out with double-stranded GFP RNA. Overall, our results indicate that the MP of CVF is putatively implicated in the suppression of RNA silencing, though further experimentation is needed to unveil the exact mode of action.

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“…The 2b suppressor gene of Tomato aspermy virus (TAV), which was used as positive control, and green fluorescent protein (GFP) (m- gfp 5-ER) [ 27 ], which was used as a silencing inducer, were cloned as described previously [ 28 ].…”

Section: Methodsmentioning

confidence: 99%

Olive Mild Mosaic Virus Coat Protein and P6 Are Suppressors of RNA Silencing, and Their Silencing Confers Resistance against OMMV

Varanda

Materatski

Campos

et al. 2018

Viruses

Self Cite

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RNA silencing is an important defense mechanism in plants, yet several plant viruses encode proteins that suppress this mechanism. In this study, the genome of the Olive mild mosaic virus (OMMV) was screened for silencing suppressors. The full OMMV cDNA and 5 OMMV open reading frames (ORFs) were cloned into the Gateway binary vector pK7WG2, transformed into Agrobacterium tumefaciens, and agroinfiltrated into N. benthamiana 16C plants. CP and p6 showed suppressor activity, with CP showing significantly higher activity than p6, yet activity that was lower than the full OMMV, suggesting a complementary action of CP and p6. These viral suppressors were then used to induce OMMV resistance in plants based on RNA silencing. Two hairpin constructs targeting each suppressor were agroinfiltrated in N. benthamiana plants, which were then inoculated with OMMV RNA. When silencing of both suppressors was achieved, a significant reduction in viral accumulation and symptom attenuation was observed as compared to those of the controls, as well as to when each construct was used alone, proving them to be effective against OMMV infection. This is the first time that a silencing suppressor was found in a necrovirus, and that two independent proteins act as silencing suppressors in a virus member of the Tombusviridae family.

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Citrus tristeza virus p23 may suppress systemic silencing but is not related to the kind of viral syndrome

Cited by 6 publications

References 41 publications

Identification and localization of Tospovirus genus-wide conserved residues in 3D models of the nucleocapsid and the silencing suppressor proteins

Identification and localization of Tospovirus genus-wide conserved residues in 3D models of the nucleocapsid and the silencing suppressor proteins

Evaluation of the RNA Silencing Suppression Activity of Three Cherry Virus F-Encoded Proteins

Olive Mild Mosaic Virus Coat Protein and P6 Are Suppressors of RNA Silencing, and Their Silencing Confers Resistance against OMMV

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