scholarly journals Suppression of RNA Silencing by TYLCV During Viral Infection

2009 ◽  
Author(s):  
Vitaly Citovsky ◽  
Yedidya Gafni
Keyword(s):  
Rna Silencing ◽  
Molecular Mechanisms ◽  
Protein S ◽  
Viral Agent ◽  
Tomato Plants ◽  
Research Findings ◽  
Tomato Pathogen ◽  
F Box Protein ◽  
Suppressor Of Rna Silencing

The Israeli isolate of Tomato yellow leaf curl geminivirus (TYLCV-Is) is a major tomato pathogen, causing extensive (up to 100%) crop losses in Israel and in the south-eastern U.S. (e.g., Georgia, Florida). Surprisingly, however, little is known about the molecular mechanisms of TYLCV-Is interactions with tomato cells. In the current BARD project, we have identified a TYLCV-Is protein, V2, which acts as a suppressor of RNA silencing, and showed that V2 interacts with the tomato (L. esculentum) member of the SGS3 (LeSGS3) protein family known to be involved in RNA silencing. This proposal will use our data as a foundation to study one of the most intriguing, yet poorly understood, aspects of TYLCV-Is interactions with its host plants – possible involvement of the host innate immune system, i.e., RNA silencing, in plant defense against TYLCV-Is and the molecular pathway(s) by which TYLCV-Is may counter this defense. Our project sought two objectives: I. Study of the roles of RNA silencing and its suppression by V2 in TYLCV-Is infection of tomato plants. II. Study of the mechanism by which V2 suppresses RNA silencing. Our research towards these goals has produced the following main achievements: • Identification and characterization of TYLCV V2 protein as a suppressor of RNA silencing. (#1 in the list of publications). • Characterization of the V2 protein as a cytoplasmic protein interacting with the plant protein SlSGS3 and localized mainly in specific, not yet identified, bodies. (#2 in the list of publications). • Development of new tools to study subcellular localization of interacting proteins (#3 in the list of publications). • Characterization of TYLCV V2 as a F-BOX protein and its possible role in target protein(s) degradation. • Characterization of TYLCV V2 interaction with a tomato cystein protease that acts as an anti-viral agent. These research findings provided significant insights into (I) the suppression of RNA silencing executed by the TYLCV V2 protein and (II) characterization some parts of the mechanism(s) involved in this suppression. The obtained knowledge will help to develop specific strategies to attenuate TYLCV infection, for example, by blocking the activity of the viral suppressor of gene silencing thus enabling the host cell silencing machinery combat the virus.

scholarly journals Inactivation of SGS3 as Molecular Basis for RNA Silencing Suppression by TYLCV V2

2013 ◽  
Author(s):  
Yedidya Gafni ◽  
Vitaly Citovsky
Keyword(s):  
Rna Silencing ◽  
Molecular Mechanisms ◽  
Rna Binding ◽  
Plant Immunity ◽  
Inhibitory Effect ◽  
Binding Activity ◽  
Plant Interactions ◽  
Subsequent Conversion ◽  
Tomato Pathogen ◽  
F Box Protein

The Israeli isolate of Tomato yellow leaf curl geminivirus(TYLCV-Is) is a major tomato pathogen, causing extensive crop losses in Israel and in the south-eastern U.S. Yet, little is known about the molecular mechanisms of its interaction with tomato cells. One of the most interesting aspects of such interaction is how the invading virus counteracts the RNA silencing response of the plant. In the former BARD project, we have shown that TYLCV-Is V2 protein is an RNA silencing suppressor, and that this suppression is carried out via the interaction of V2 with the SGS3 component of the plant RNA silencing machinery. This reported project was meant to use our data as a foundation to elucidate the molecular mechanism by which V2 affects the SGS3 activity. While this research is likely to have an important impact on our understanding of basic biology of virus-plant interactions and suppression of plant immunity, it also will have practical implications, helping to conceive novel strategies for crop resistance to TYLCV-Is. Our preliminary data in regard to V2 activities and our present knowledge of the SGS3 function suggest likely mechanisms for the inhibitory effect of V2 on SGS3. We have shown that V2 possess structural and functional hallmarks of an F-box protein, suggesting that it may target SGS3 for proteasomal degradation. SGS3 contains an RNA-binding domain and likely functions to protect the cleavage produces of the primary transcript for subsequent conversion to double-stranded forms; thus, V2 may simply block the RNA binding activity of SGS3. V2 may also employ a combination of these mechanisms. These and other possibilities were tested in this reported project. 

scholarly journals Characterization of Hypovirus-Derived Small RNAs Generated in the Chestnut Blight Fungus by an Inducible DCL-2-Dependent Pathway

2008 ◽  
Vol 82 (6) ◽  
pp. 2613-2619 ◽  
Author(s):  
Xuemin Zhang ◽  
Gert C. Segers ◽  
Qihong Sun ◽  
Fuyou Deng ◽  
Donald L. Nuss
Keyword(s):  
Small Rnas ◽  
Rna Silencing ◽  
Cryphonectria Parasitica ◽  
Chestnut Blight ◽  
Fungal Host ◽  
Chestnut Blight Fungus ◽  
Mutant Strains ◽  
Suppressor Of Rna Silencing ◽  
Dependent Pathway

ABSTRACT The disruption of one of two dicer genes, dcl-2, of the chestnut blight fungus Cryphonectria parasitica was recently shown to increase susceptibility to mycovirus infection (G. C. Segers, X. Zhang, F. Deng, Q. Sun, and D. L. Nuss, Proc. Natl. Acad. Sci. USA 104:12902-12906, 2007). We now report the accumulation of virus-derived small RNAs (vsRNAs) in hypovirus CHV1-EP713-infected wild-type and dicer gene dcl-1 mutant C. parasitica strains but not in hypovirus-infected dcl-2 mutant and dcl-1 dcl-2 double-mutant strains. The CHV1-EP713 vsRNAs were produced from both the positive and negative viral RNA strands at a ratio of 3:2 in a nonrandom distribution along the viral genome. We also show that C. parasitica responds to hypovirus and mycoreovirus infections with a significant increase (12- to 20-fold) in dcl-2 expression while the expression of dcl-1 is increased only modestly (2-fold). The expression of dcl-2 is further increased (∼35-fold) following infection with a hypovirus CHV1-EP713 mutant that lacks the p29 suppressor of RNA silencing. The combined results demonstrate the biogenesis of mycovirus-derived small RNAs in a fungal host through the action of a specific dicer gene, dcl-2. They also reveal that dcl-2 expression is significantly induced in response to mycovirus infection by a mechanism that appears to be repressed by the hypovirus-encoded p29 suppressor of RNA silencing.

Characterization of plant miRNAs and small RNAs derived from potato spindle tuber viroid (PSTVd) in infected tomato

2010 ◽  
Vol 391 (12) ◽  
Author(s):  
Natalie Diermann ◽  
Jaroslav Matoušek ◽  
Markus Junge ◽  
Detlev Riesner ◽  
Gerhard Steger
Keyword(s):  
Transcription Factors ◽  
Small Rnas ◽  
Rna Silencing ◽  
Potato Spindle Tuber Viroid ◽  
Regulation Of Transcription ◽  
Tomato Plants ◽  
Sequence Variations ◽  
Infected Tomato ◽  
Minor Sequence

Abstract To defend against invading pathogens, plants possess RNA silencing mechanisms involving small RNAs (miRNAs, siRNAs). Also viroids – plant infectious, non-coding, unencapsidated RNA – cause the production of viroid-specific small RNAs (vsRNA), but viroids do escape the cytoplasmic silencing mechanism. Viroids with minor sequence variations can produce different symptoms in infected plants, suggesting an involvement of vsRNAs in symptom production. We analyzed by deep sequencing the spectrum of vsRNAs induced by the PSTVd strain AS1, which causes strong symptoms such as dwarfing and necrosis upon infection of tomato plants cv Rutgers. Indeed, vsRNAs found with highest frequency mapped to the pathogenicity-modulating domain of PSTVd, supporting an involvement of vsRNAs in symptom production. Furthermore, in PSTVd AS1-infected plants the accumulation of some endogenous miRNAs, which are involved in leaf development via regulation of transcription factors, is suppressed. The latter finding supports the hypothesis that a miRNA-dependent (mis)regula-tion of transcription factors causes the viroid symptoms.

scholarly journals Copy number-dependent DNA methylation of the Pyricularia oryzae MAGGY retrotransposon is triggered by DNA damage

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Ba Van Vu ◽  
Quyet Nguyen ◽  
Yuki Kondo-Takeoka ◽  
Toshiki Murata ◽  
Naoki Kadotani ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Copy Number ◽  
Rna Silencing ◽  
Molecular Mechanisms ◽  
De Novo ◽  
Pyricularia Oryzae ◽  
Transcriptional Gene Silencing ◽  
Physical Interaction ◽  
Uncharacterized Protein ◽  
Form Complex

AbstractTransposable elements are common targets for transcriptional and post-transcriptional gene silencing in eukaryotic genomes. However, the molecular mechanisms responsible for sensing such repeated sequences in the genome remain largely unknown. Here, we show that machinery of homologous recombination (HR) and RNA silencing play cooperative roles in copy number-dependent de novo DNA methylation of the retrotransposon MAGGY in the fungusPyricularia oryzae. Genetic and physical interaction studies revealed thatRecAdomain-containing proteins, includingP. oryzaehomologs ofRad51, Rad55, andRad57, together with an uncharacterized protein, Ddnm1, form complex(es) and mediate either the overall level or the copy number-dependence of de novo MAGGY DNA methylation, likely in conjunction with DNA repair. Interestingly,P. oryzaemutants of specific RNA silencing components (MoDCL1andMoAGO2)were impaired in copy number-dependence of MAGGY methylation. Co-immunoprecipitation of MoAGO2 and HR components suggested a physical interaction between the HR and RNA silencing machinery in the process.

scholarly journals Genetic mapping and transcriptomic characterization of a new fuzzless-tufted cottonseed mutant

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Qian-Hao Zhu ◽  
Warwick Stiller ◽  
Philippe Moncuquet ◽  
Stuart Gordon ◽  
Yuman Yuan ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Agronomic Traits ◽  
Gene Families ◽  
Mutant Phenotype ◽  
Wild Type ◽  
Calcium Dependent ◽  
Dependent Protein ◽  
Flanking Region ◽  
Comparative Transcriptomic Analysis

Abstract Fiber mutants are unique and valuable resources for understanding the genetic and molecular mechanisms controlling initiation and development of cotton fibers that are extremely elongated single epidermal cells protruding from the seed coat of cottonseeds. In this study, we reported a new fuzzless-tufted cotton mutant (Gossypium hirsutum) and showed that fuzzless-tufted near-isogenic lines (NILs) had similar agronomic traits and a higher ginning efficiency compared to their recurrent parents with normal fuzzy seeds. Genetic analysis revealed that the mutant phenotype is determined by a single incomplete dominant locus, designated N5. The mutation was fine mapped to an approximately 250-kb interval containing 33 annotated genes using a combination of bulked segregant sequencing, SNP chip genotyping, and fine mapping. Comparative transcriptomic analysis using 0–6 days post-anthesis (dpa) ovules from NILs segregating for the phenotypes of fuzzless-tufted (mutant) and normal fuzzy cottonseeds (wild-type) uncovered candidate genes responsible for the mutant phenotype. It also revealed that the flanking region of the N5 locus is enriched with differentially expressed genes (DEGs) between the mutant and wild-type. Several of those DEGs are members of the gene families with demonstrated roles in cell initiation and elongation, such as calcium-dependent protein kinase and expansin. The transcriptome landscape of the mutant was significantly reprogrammed in the 6 dpa ovules and, to a less extent, in the 0 dpa ovules, but not in the 2 and 4 dpa ovules. At both 0 and 6 dpa, the reprogrammed mutant transcriptome was mainly associated with cell wall modifications and transmembrane transportation, while transcription factor activity was significantly altered in the 6 dpa mutant ovules. These results imply a similar molecular basis for initiation of lint and fuzz fibers despite certain differences.

scholarly journals A Concerted Action of UBA5 C-Terminal Unstructured Regions Is Important for Transfer of Activated UFM1 to UFC1

2021 ◽  
Vol 22 (14) ◽  
pp. 7390
Author(s):  
Nicole Wesch ◽  
Frank Löhr ◽  
Natalia Rogova ◽  
Volker Dötsch ◽  
Vladimir V. Rogov
Keyword(s):  
Cellular Localization ◽  
Molecular Mechanisms ◽  
Biochemical Characterization ◽  
Effective Interaction ◽  
Regulatory Region ◽  
Titration Calorimetry ◽  
Enzymatic Reactions ◽  
Cellular Processes ◽  
Mechanism Of Interaction

Ubiquitin fold modifier 1 (UFM1) is a member of the ubiquitin-like protein family. UFM1 undergoes a cascade of enzymatic reactions including activation by UBA5 (E1), transfer to UFC1 (E2) and selective conjugation to a number of target proteins via UFL1 (E3) enzymes. Despite the importance of ufmylation in a variety of cellular processes and its role in the pathogenicity of many human diseases, the molecular mechanisms of the ufmylation cascade remains unclear. In this study we focused on the biophysical and biochemical characterization of the interaction between UBA5 and UFC1. We explored the hypothesis that the unstructured C-terminal region of UBA5 serves as a regulatory region, controlling cellular localization of the elements of the ufmylation cascade and effective interaction between them. We found that the last 20 residues in UBA5 are pivotal for binding to UFC1 and can accelerate the transfer of UFM1 to UFC1. We solved the structure of a complex of UFC1 and a peptide spanning the last 20 residues of UBA5 by NMR spectroscopy. This structure in combination with additional NMR titration and isothermal titration calorimetry experiments revealed the mechanism of interaction and confirmed the importance of the C-terminal unstructured region in UBA5 for the ufmylation cascade.

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