The Experts below are selected from a list of 1074 Experts worldwide ranked by ideXlab platform
Anne E Simon - One of the best experts on this subject based on the ideXlab platform.
-
Satellite RNA-Mediated Resistance to Turnip Crinkle Virus in Arabidopsis lnvolves a Reduction in Virus Movement
2013Co-Authors: Qingzhong Kong, Jianlong Wang, Anne E SimonAbstract:Satellite RNAs (sat-RNAs) are parasites of Viruses that can mediate resistance to the helper Virus. We previously showed that a sat-RNA (sat-RNA C) of Turnip Crinkle Virus (TCV), which normally intensifies symptoms of TCV, is able to attenuate symptoms when TCV contains the coat protein (CP) of cardamine chlorotic fleck Virus (TCV-CPccw). We have now determined that sat-RNA C also attenuates symptoms of TCV containing an alteration in the initiating AUG of the CP open reading frame (TCV-CPm). TCV-CPm, which is able to move systemically in both the TCV-susceptible ecotype Columbia (Col-O) and the TCV-resistant ecotype Dijon (Di-O), produced a reduced level of CP and no detectable virions in infected plants. Sat-RNA C reduced the accumulation of TCV-CPm by <25 % in protoplasts while reducing the level of TCV-CPm by 90 to 100 % in uninoculated leaves of COLO and Di-O. Our results suggest that in the presence of a reduced level of a possibly altered CP, sat-RNA C reduces Virus long-distance movement in a manner that is independent of the salicylic acid-dependent defense pathway
-
a local interactive network of 3 rna elements supports translation and replication of Turnip Crinkle Virus
Journal of Virology, 2012Co-Authors: Xuefeng Yuan, Kerong Shi, Anne E SimonAbstract:ABSTRACT The majority of the 3′ untranslated region (UTR) of Turnip Crinkle Virus (TCV) was previously identified as forming a highly interactive structure with a ribosome-binding tRNA-shaped structure (TSS) acting as a scaffold and undergoing a widespread conformational shift upon binding to RNA-dependent RNA polymerase (RdRp). Tertiary interactions in the region were explored by identifying two highly detrimental mutations within and adjacent to a hairpin H4 upstream of the TSS that reduce translation in vivo and cause identical structural changes in the loop of the 3′ terminal hairpin Pr. Second-site changes that compensate for defects in translation/accumulation and reverse the structural differences in the Pr loop were found in the Pr stem, as well as in a specific stem within the TSS and within the capsid protein (CP) coding region, suggesting that the second-site changes were correcting a conformational defect and not restoring specific base pairing. The RdRp-mediated conformational shift extended upstream through this CP open reading frame (ORF) region after bypassing much of an intervening, largely unstructured region, supporting a connection between 3′ elements and coding region elements. These data suggest that the Pr loop, TSS, and H4 are central elements in the regulation of translation and replication in TCV and allow for development of an RNA interactome that maps the higher-order structure of a postulated RNA domain within the 3′ region of a plus-strand RNA Virus.
-
cryo electron microscopy cryo em structure of a cap independent translational enhancer of the Turnip Crinkle Virus tcv bound to the eukaryotic ribosome
Biophysical Journal, 2012Co-Authors: Gyanesh Sharma, Anne E Simon, Bruce A Shapiro, Jonathan D Dinman, Vera A. Stupina, Jesper Pallesen, Joachim FrankAbstract:Many plant Viruses, unlike animal Viruses, use 3′ translational enhancers that function by unknown mechanism to achieve translation initiation. A translational enhancer in the 3′-UTR of Turnip Crinkle Virus (TCV) has been shown to synergistically enhance translation when associated with the TCV 5′-UTR. The major enhancement has been shown, biochemically, due to a T-shaped structure (TSS) which binds to the 80S ribosomes with the aid of a pseudoknot that mimics the tRNA acceptor stem. The research presented here focuses on the structural interaction of the TSS structure with the 80S eukaryotic ribosome from Saccharomyces cerevisiae using the single-particle cryo-EM reconstruction technique. Our preliminary work shows that the density corresponding to the TSS structure is directly visible in the cryo-EM map, and most of the ribosomes containing the TSS structure are in the ratcheted-like intersubunit-rotated state. These results match the biochemical results. We are currently investigating the detailed binding interactions between the TSS and the ribosome. Interpretation of this cryo-EM map is a first step toward an understanding of the molecular mechanism of translation enhancement and regulation by the TSS structure.
-
evolution of a helper Virus derived ribosome binding translational enhancer in an untranslated satellite rna of Turnip Crinkle Virus
Virology, 2011Co-Authors: Rong Guo, Arturas Meskauskas, Jonathan D Dinman, Anne E SimonAbstract:Abstract SatC is a noncoding subviral RNA associated with Turnip Crinkle Virus (TCV). A 100-nt stretch in the 3′ UTR of TCV contains three hairpins and two pseudoknots that fold into a tRNA-shaped structure (TSS) that binds 80S ribosomes. The 3′ half of satC is derived from TCV and contains 6-nt differences in the TSS-analogous region. SatC binds poorly to 80S ribosomes, and molecular modeling that predicted the 3D structure of the TSS did not predict a similar structure for satC. When the satC TSS region was step-wise converted to the original TCV TSS bases, ribosome binding increased to TCV TSS levels without significantly affecting satC replication. However, mutant satC was less fit when accumulating in plants and gave rise to numerous second site changes that weakened one of two satC conformations. These results suggest that minor changes from the original TCV sequence in satC reflect requirements other than elimination of ribosome binding.
-
the capsid protein of Turnip Crinkle Virus overcomes two separate defense barriers to facilitate systemic movement of the Virus in arabidopsis
Journal of Virology, 2010Co-Authors: Mingxia Cao, Anne E Simon, Kristen Willie, Junyan Lin, Xiuchun Zhang, Margaret G Redinbaugh, Jack T MorrisAbstract:The capsid protein (CP) of Turnip Crinkle Virus (TCV) is a multifunctional protein needed for Virus assembly, suppression of RNA silencing-based antiviral defense, and long-distance movement in infected plants. In this report, we have examined genetic requirements for the different functions of TCV CP and evaluated the interdependence of these functions. A series of TCV mutants containing alterations in the CP coding region were generated. These alterations range from single-amino-acid substitutions and domain truncations to knockouts of CP translation. The latter category also contained two constructs in which the CP coding region was replaced by either the cDNA of a silencing suppressor of a different Virus or that of green fluorescent protein. These mutants were used to infect Arabidopsis plants with diminished antiviral silencing capability (dcl2 dcl3 dcl4 plants). There was a strong correlation between the ability of mutants to reach systemic leaves and the silencing suppressor activity of mutant CP. Virus particles were not essential for entry of the viral genome into vascular bundles in the inoculated leaves in the absence of antiviral silencing. However, Virus particles were necessary for egress of the viral genome from the vasculature of systemic leaves. Our experiments demonstrate that TCV CP not only allows the viral genome to access the systemic movement channel through silencing suppression but also ensures its smooth egress by way of assembled Virus particles. These results illustrate that efficient long-distance movement of TCV requires both functions afforded by the CP.
Jack T Morris - One of the best experts on this subject based on the ideXlab platform.
-
a nuclear fraction of Turnip Crinkle Virus capsid protein is important for elicitation of the host resistance response
Virus Research, 2015Co-Authors: Sunghwan Kang, Jack T MorrisAbstract:The N-terminal 25 amino acids (AAs) of Turnip Crinkle Virus (TCV) capsid protein (CP) are recognized by the resistance protein HRT to trigger a hypersensitive response (HR) and systemic resistance to TCV infection. This same region of TCV CP also contains a motif that interacts with the transcription factor TIP, as well as a nuclear localization signal (NLS). However, it is not yet known whether nuclear localization of TCV CP is needed for the induction of HRT-mediated HR and resistance. Here we present new evidence suggesting a tight correlation between nuclear inclusions formed by CP and the manifestation of HR. We show that a fraction of TCV CP localized to cell nuclei to form discrete inclusion-like structures, and a mutated CP (R6A) known to abolish HR failed to form nuclear inclusions. Notably, TIP-CP interaction augments the inclusion-forming activity of CP by tethering inclusions to the nuclear membrane. This TIP-mediated augmentation is also critical for HR resistance, as another CP mutant (R8A) known to elicit a less restrictive HR, though still self-associated into nuclear inclusions, failed to direct inclusions to the nuclear membrane due to its inability to interact with TIP. Finally, exclusion of CP from cell nuclei abolished induction of HR. Together, these results uncovered a strong correlation between nuclear localization and nuclear inclusion formation by TCV CP and induction of HR, and suggest that CP nuclear inclusions could be the key trigger of the HRT-dependent, yet TIP-reinforced, resistance to TCV.
-
a spectrum of hrt dependent hypersensitive responses elicited by the 52 amino acid n terminus of Turnip Crinkle Virus capsid protein and its mutants
Virus Research, 2015Co-Authors: Sunghwan Kang, Jack T MorrisAbstract:The capsid protein (CP) of Turnip Crinkle Virus (TCV) is the elicitor of hypersensitive response (HR) and resistance mediated by the resistance protein HRT in the Di-17 ecotype of Arabidopsis. Here we identified the N-terminal 52-amino-acid R domain of TCV CP as the elicitor of HRT-dependent HR in Nicotiana benthamiana. Mutating this domain at position 6 (R6A), but not at positions 8 (R8A) or 14 (G14A), abolished HR in N. benthamiana. However, on Di-17 Arabidopsis leaves only R8A R domain elicited visible epidermal HR. When incorporated in infectious TCV RNAs, R8A and G14A mutations exerted dramatically different effects in Di-17 plants, as R8A caused systemic cell death whereas G14A led to complete restriction of the mutant Virus. This continual spectrum of HR and resistance responses elicited by various R domain mutants suggests that the CP–HRT interaction could be perturbed by conformational changes in the R domain of TCV CP.
-
Gene Function Requires Interaction between a NAC Protein and Viral Capsid Protein to Confer Resistance to Turnip Crinkle Virus
2014Co-Authors: Tao Ren, Jack T MorrisAbstract:An Arabidopsis protein was found to interact specifically with the capsid protein (CP) of Turnip Crinkle Virus (TCV) through yeast two-hybrid screening. This protein, designated TIP (for TCV-interacting protein), was found to be a mem-ber of the recently recognized NAC family of proteins. NAC proteins have been implicated in the regulation of develop-ment of plant embryos and flowers. TIP alone was able to activate expression of reporter genes in yeast if fused to a DNA binding domain, suggesting that it may be a transcriptional activator. The TIP binding region in the TCV CP has been mapped to the N-terminal 25 amino acids. Site-directed mutagenesis within this region revealed that loss of the TIP–CP interaction in the yeast two-hybrid assay correlated with loss of the ability of TCV to induce the hypersensitive response and resistance in the TCV-resistant Arabidopsis ecotype Dijon (Di-0 and its inbred line Di-17). These data suggest that TIP is an essential component in the TCV resistance response pathway
-
Turnip Crinkle Virus coat protein inhibits the basal immune response to Virus invasion in arabidopsis by binding to the nac transcription factor tip
Virology, 2014Co-Authors: Teresa Donze, Paul Twigg, Jack T MorrisAbstract:Turnip Crinkle Virus (TCV) has been shown to interact with a NAC transcription factor, TIP, of Arabidopsis thaliana, via its coat protein (CP). This interaction correlates with the resistance response manifested in TCV-resistant Arabidopsis ecotype Di-17. We report that failure of a mutated CP to interact with TIP triggered the corresponding TCV mutant (R6A) to cause more severe symptoms in the TCV-susceptible ecotype Col-0. We hypothesized that TCV regulates antiviral basal immunity through TIP-CP interaction. Consistent with this hypothesis, we found that the rate of accumulation of R6A was measurably slower than wild-type TCV over the course of an infection. Notably, R6A was able to accumulate at similar rates as wild-type TCV in mutant plants with defects in salicylic acid (SA) signaling. Finally, plants with altered TIP expression provided evidence R6A's inability to evade the basal resistance response was likely associated with loss of ability for CP to bind TIP.
-
the capsid protein of Turnip Crinkle Virus overcomes two separate defense barriers to facilitate systemic movement of the Virus in arabidopsis
Journal of Virology, 2010Co-Authors: Mingxia Cao, Anne E Simon, Kristen Willie, Junyan Lin, Xiuchun Zhang, Margaret G Redinbaugh, Jack T MorrisAbstract:The capsid protein (CP) of Turnip Crinkle Virus (TCV) is a multifunctional protein needed for Virus assembly, suppression of RNA silencing-based antiviral defense, and long-distance movement in infected plants. In this report, we have examined genetic requirements for the different functions of TCV CP and evaluated the interdependence of these functions. A series of TCV mutants containing alterations in the CP coding region were generated. These alterations range from single-amino-acid substitutions and domain truncations to knockouts of CP translation. The latter category also contained two constructs in which the CP coding region was replaced by either the cDNA of a silencing suppressor of a different Virus or that of green fluorescent protein. These mutants were used to infect Arabidopsis plants with diminished antiviral silencing capability (dcl2 dcl3 dcl4 plants). There was a strong correlation between the ability of mutants to reach systemic leaves and the silencing suppressor activity of mutant CP. Virus particles were not essential for entry of the viral genome into vascular bundles in the inoculated leaves in the absence of antiviral silencing. However, Virus particles were necessary for egress of the viral genome from the vasculature of systemic leaves. Our experiments demonstrate that TCV CP not only allows the viral genome to access the systemic movement channel through silencing suppression but also ensures its smooth egress by way of assembled Virus particles. These results illustrate that efficient long-distance movement of TCV requires both functions afforded by the CP.
T J Morris - One of the best experts on this subject based on the ideXlab platform.
-
cell to cell movement of Turnip Crinkle Virus is controlled by two small open reading frames that function in trans
Virology, 1998Co-Authors: T J MorrisAbstract:Previous studies on Turnip Crinkle Virus (TCV) have suggested that the two small, centrally located ORFs, conserved in all CarmoViruses, are both required for cell-to-cell movement (Hacker et al., 1992). We now demonstrate that the cell-to-cell movement of TCV is mediated by in trans complementation of the two proteins. First, both of the putative movement proteins (MPs p8 and p9) were shown to be translated in vitro from transcripts representing the 1.7-kb subgenomic RNA. Western blot analysis, using antisera prepared against GST fusion proteins of both genes, was then used to show that the p8 but not the p9 protein accumulated to detectable levels in particulate fractions of infected cells. Cell-to-cell movement of various MP mutants in Arabidopsis was evaluated by in situ hybridization of inoculated leaves. Changes in either of the two MP genes resulted in failure of the mutants to move cell-to-cell. Coat protein was found to be unnecessary for cell-to-cell movement. Complementation of cell-to-cell movement by co-inoculating p8-defective mutants with a p9-defective mutant resulted in delayed systemic infection. In contrast, efficient cell-to-cell movement was achieved when the MP mutants were inoculated into transgenic plants expressing the corresponding functional gene(s). These experiments provide further evidence that both MP genes encoded by CarmoViruses must function in trans in the same cell in order to mediate cell-to-cell movement.
-
encapsidation of Turnip Crinkle Virus is defined by a specific packaging signal and rna size
Journal of Virology, 1997Co-Authors: T J MorrisAbstract:A protoplast infection assay has been used to reliably examine the viral RNA encapsidation of Turnip Crinkle Virus (TCV). Analysis of the encapsidation of various mutant viral RNAs revealed that a 186-nucleotide (nt) region at the 3' end of the coat protein (CP) gene, with a bulged hairpin loop of 28 nt as its most essential element, was indispensable for TCV RNA encapsidation. When RNA fragments containing the 186-nt region were used to replace the CP gene of a different Virus, tomato bushy stunt Virus, the resulting chimeric viral RNAs were encapsidated into TCV virions. Furthermore, analysis of the encapsidated chimeric RNA species established that the RNA size was an important determinant of the TCV assembly process.
-
Turnip Crinkle Virus genes required for rna replication and Virus movement
Virology, 1992Co-Authors: D L Hacker, N Wei, I T D Petty, T J MorrisAbstract:We have used infectious in vitro transcripts from mutagenized Turnip Crinkle Virus (TCV) cDNA clones to identify the gene products required for viral RNA replication, virion assembly, and intercellular movement. Previous sequence analysis of the TCV genome revealed the presence of five open reading frames which had the potential to encode gene products of 88, 38, 28, 9, and 8 kDa. Inoculation of protoplasts with infectious RNA revealed that only the p28 and p88 gene products are required for viral RNA synthesis. Although the p8 and p9 gene products were dispensable for RNA replication and virion assembly in protoplasts, mutations in the p8 and p9 genes prevented the production of systemic infections in plants. No viral RNA or protein was observed in the inoculated or systemic leaves of plants inoculated with transcripts synthesized from p8 or p9 mutant cDNAs. In contrast to these results, viral RNA was recovered from the inoculated, but not the systemic leaves, of plants inoculated with an RNA lacking the coat protein (CP) gene. With the CP mutant, no symptoms were observed on normally systemic hosts, but small local lesions were induced on Chenopodium amaranticolor. These results indicate that p8, p9, and CP are required for viral movement.
-
interactions between viral coat protein and a specific binding region on Turnip Crinkle Virus rna
Journal of Molecular Biology, 1991Co-Authors: N Wei, T J MorrisAbstract:The Turnip Crinkle Virus coat protein binding sites in the ribonucleoprotein complex resulting from virion dissociation have been identified previously. In this study, RNA binding characteristics of viral coat protein to a region encompassing the protected RNA fragments Fa, Ff, and Fc (Fafc) have been investigated further using an RNA transcript (the Fafc fragment). These experiments have shown that coat protein requires no additional viral RNA elements to bind to this region. Such binding was shown to be specific for Turnip Crinkle Virus coat protein using an ultra-violet light cross-linking assay. Gel mobility shift analyses demonstrated that the protein-RNA interactions produced two complexes: a homogeneous small ribonucleoprotein complex, and larger complexes which failed to migrate into gels. High salt and limiting protein concentrations favored the formation of the small ribonucleoprotein complex, whereas low salt and excess protein concentrations favored the larger complexes. RNA competition experiments demonstrated that small ribonucleoprotein complex formation coincided with specific RNA binding of the coat protein to the Fafc fragment. In addition, the coat protein possessed a poly(U)-binding site(s), which enabled it to interact with single-stranded RNA in a sequence non-specific manner to form large complexes. The results suggest that the coat protein contains both specific and non-specific RNA binding activities located at physically distinct sites. These results are consistent with the proposed assembly model for Turnip Crinkle Virus.
-
point mutations in the Turnip Crinkle Virus capsid protein affect the symptoms expressed by nicotiana benthamiana
Virology, 1991Co-Authors: Louis A Heaton, N Wei, T C Lee, T J MorrisAbstract:In an effort to determine the biological function(s) of the capsid protein protruding domains unique to the plant carmo- and tombusViruses, we constructed Turnip Crinkle Virus (TCV) mutants in which tandem, in-frame translation terminators replaced the first two codons of the five-amino acid hinge between the shell and the protruding domains of the TCV capsid protein. One of the mutants replicated in inoculated leaves and protoplasts without detectable accumulation of capsid protein. The mutant lacked the capacity to move systemically in Brassica campestris and Nicotiana benthamiana. After 8 weeks, revertant virions that had regained the capacity to move systemically were purified and found to have sense codons at the positions of the introduced translation terminators. One of the revertants, with amino acid substitutions in the hinge, elicited milder symptoms than those elicited by the wild-type Virus, and another elicited more severe symptoms. Oligonucleotide-directed mutagenesis was used to show that the hinge mutations were sufficient to elicit the milder, but not the more severe, symptom syndrome. Single amino acid substitutions were also shown to be sufficient to elicit the milder, but not the more severe, symptoms.
Sekman Wong - One of the best experts on this subject based on the ideXlab platform.
-
molecular modeling and interaction between arabidopsis sulfite oxidase and the gw motif of Turnip Crinkle Virus coat protein
Virology, 2020Co-Authors: Srinivasaraghavan Kannan, Sekman Wong, Chandra S Verma, Kunchithapadam SwaminathanAbstract:Previous study has shown that Hibiscus sulfite oxidase (SO) interacts with Hibiscus chlorotic ringspot Virus (HCRSV) coat protein (CP) and triggers sulfur enhanced defense (SED). In this study, we show the interaction of Arabidopsis SO (AtSO) and Turnip Crinkle Virus (TCV) CP in Arabidopsis thaliana plants. We identified the binding sites of TCV CP (W274) and AtSO (D223) using bioinformatics and confirmed it experimentally. Mutation of binding site W274 to A274 in TCV CP resulted in failure of TCV infection. TCV accumulation in SO over-expression (SO_OE) plants was lower than that in wild-type (WT) and SO knock-out (SO_KO) plants at 7 dpi but reached a level similar to that of WT and SO_KO plants at 10 dpi. AtSO competed with Argonaute 1 (AGO1) for TCV CP binding in vitro. AtSO may serve as an anti-viral factor through sequestering TCV CP for binding with AGO1 and confers Virus resistance.
-
upregulation of linc ap2 is negatively correlated with ap2 gene expression with Turnip Crinkle Virus infection in arabidopsis thaliana
Plant Cell Reports, 2016Co-Authors: Ruimin Gao, Sekman Wong, Peng Liu, Nadia Irwanto, De Rong LohAbstract:A long intergenic noncoding RNA LINC - AP2 is upregulated and negatively correlated with AP2 gene expression with Turnip Crinkle Virus infection in Arabidopsis. Plant vegetative growth and floral reproductive structure were severely retarded and distorted in Turnip Crinkle Virus (TCV)-infected Arabidopsis thaliana. Compared to mock-inoculated plants, the stamen filaments were shorter in flowers of TCV-infected plants. However, TCV-infected plants can still produce normal seeds through artificial pollination, indicating both its pollen and stigma were biologically functional. From our high-throughput RNA-Seq transcriptome analysis, a floral structure-related APETALA2 (AP2) gene was found to be downregulated and its neighboring long intergenic noncoding RNAs (lincRNA), At4NC069370 (named LINC-AP2 in this study), were upregulated significantly in TCV-infected plants. This LINC-AP2 was further confirmed for its existence using 5'RACE technology. LINC-AP2 overexpression (LINC-AP2 OE) transgenic Arabidopsis plants were generated to compare with TCV-infected WT plants. TCV-infected LINC-AP2 OE plants which contained lower AP2 gene expression displayed more severe symptoms (including floral structure distortion) and higher TCV-CP gene transcript and coat protein levels. Furthermore, compared to TCV-infected WT plants, TCV-infected ap2 mutant plants failed to open their flower buds and displayed more severe viral symptoms. In conclusion, upregulation of LINC-AP2 is negatively correlated with AP2 gene expression with TCV infection in Arabidopsis.
-
genome wide transcriptomic analysis reveals correlation between higher wrky61 expression and reduced symptom severity in Turnip Crinkle Virus infected arabidopsis thaliana
Scientific Reports, 2016Co-Authors: Ruimin Gao, Sekman Wong, Peng Liu, Yuhan YongAbstract:Turnip Crinkle Virus (TCV) is a carmoVirus that infects many Arabidopsis ecotypes. Most studies mainly focused on discovery of resistance genes against TCV infection, and there is no Next Generation Sequencing based comparative genome wide transcriptome analysis reported. In this study, RNA-seq based transcriptome analysis revealed that 238 (155 up-regulated and 83 down-regulated) significant differentially expressed genes with at least 15-fold change were determined. Fifteen genes (including upregulated, unchanged and downregulated) were selected for RNA-seq data validation using quantitative real-time PCR, which showed consistencies between these two sets of data. GO enrichment analysis showed that numerous terms such as stress, immunity, defence and chemical stimulus were affected in TCV-infected plants. One putative plant defence related gene named WRKY61 was selected for further investigation. It showed that WRKY61 overexpression plants displayed reduced symptoms and less Virus accumulation, as compared to wild type (WT) and WRKY61 deficient lines, suggesting that higher WRKY61 expression level reduced TCV viral accumulation. In conclusion, our transcriptome analysis showed that global gene expression was detected in TCV-infected Arabidopsis thaliana. WRKY61 gene was shown to be negatively correlated with TCV infection and viral symptoms, which may be connected to plant immunity pathways.
-
host dependent effects of the 3 untranslated region of Turnip Crinkle Virus rna on accumulation in hibiscus and arabidopsis
Journal of General Virology, 2013Co-Authors: Sekman WongAbstract:The 3' untranslated region (UTR) of Turnip Crinkle Virus (TCV) RNA is 253 nt long (nt 3798-4050) with a 27 nt hairpin structure near its 3' terminus. In this study, the roles of the 3' UTR in Virus accumulation were investigated in protoplasts of Hibiscus cannabinus L. and Arabidopsis thaliana (L.) Heynh. Our results showed that, in Hibiscus protoplasts, the minimal 3' UTR essential for TCV accumulation extends from nt 3922 to 4050, but that maintenance of Virus accumulation at wild-type (wt) levels requires the full-length 3' UTR. However, in Arabidopsis protoplasts, only 33 nt (nt 4018-4050) at the 3' extremity of the UTR is required for wt levels of accumulation, whereas other parts of the 3' UTR are dispensable. The 27 nt hairpin within the 33 nt region is essential for Virus accumulation in both Hibiscus and Arabidopsis protoplasts. However, transposition of nucleotides in base pairs within the upper or lower stems has no effect on Virus accumulation in either Hibiscus or Arabidopsis protoplasts, and alterations of the loop sequence also fail to affect replication. Disruption of the upper or lower stems and deletion of the loop sequence reduce viral accumulation in Arabidopsis protoplasts, but abolish Virus accumulation in Hibiscus protoplasts completely. These results indicate that strict conservation of the hairpin structure is more important for replication in Hibiscus than in Arabidopsis protoplasts. In conclusion, both the 3' UTR primary sequence and the 3'-terminal hairpin structure influence TCV accumulation in a host-dependent manner.
Kristin K Wobbe - One of the best experts on this subject based on the ideXlab platform.
-
Mutational analysis of Turnip Crinkle Virus movement protein p8.
Molecular plant pathology, 2001Co-Authors: Muslum Akgoz, Que N. Nguyen, Ann E. Talmadge, Katherine E. Drainville, Kristin K WobbeAbstract:Summary Turnip Crinkle Virus encodes two proteins, p8 and p9, that are both required for cell-to-cell movement. The p8 movement protein has been demonstrated to bind RNA in a cooperative manner, although, similar to many other plant Virus movement proteins, it contains no canonical RNA binding domain(s). However, three positively charged regions of p8 may potentially form ionic interactions with the RNA backbone. To identify functional regions of p8, a series of alanine and deletion scanning mutations were produced. The effects of these mutations were analysed using both in vitro RNA binding assays and in vivo infections of susceptible (Di-3) and resistant (Di-17) Arabidopsis thaliana plants. Several mutants that have reduced RNA binding ability were also demonstrated to be movement deficient and replication competent. Based on these results, there appear to be two regions, located between amino acids 18 and 31, and 50 and 72, that are required for RNA binding. Furthermore, additional regions (amino acids 12-15, and 34-37) appear to play a role in vivo unrelated to in vitro RNA binding activity.
-
the amino terminus of the coat protein of Turnip Crinkle Virus is the avr factor recognized by resistant arabidopsis
Molecular Plant-microbe Interactions, 2000Co-Authors: Yajuan Zhao, Daniel F Klessig, Leanna Delgrosso, Erbay Yigit, Dmaris Amick Dempsey, Kristin K WobbeAbstract:We have isolated three naturally occurring strains of Turnip Crinkle Virus (TCV) that break resistance in Di-17 Arabidopsis. Two mutations in the N terminus of the TCV coat protein, D4N and P5S, were shown to confer this phenotype. Thus, this region of the coat protein is involved in eliciting resistance responses in Arabidopsis.
-
a single amino acid change in Turnip Crinkle Virus movement protein p8 affects rna binding and virulence on arabidopsis thaliana
Journal of Virology, 1998Co-Authors: Kristin K Wobbe, Dmaris Amick Dempsey, Muslum Akgoz, Daniel F KlessigAbstract:Comparison of the symptoms caused by Turnip Crinkle Virus strain M (TCV-M) and TCV-B infection of a resistant Arabidopsis thaliana line termed Di-17 demonstrates that TCV-B has a greater ability to spread in planta. This ability is due to a single amino acid change in the viral movement protein p8 and inversely correlates with p8 RNA binding affinity.
-
identification of an arabidopsis locus required for resistance to Turnip Crinkle Virus
Plant Journal, 1997Co-Authors: Dmaris Amick Dempsey, Kristin K Wobbe, Sudam M Pathirana, Daniel F KlessigAbstract:Inoculation of Turnip Crinkle Virus (TCV) into a (TCV)-resistant line of Arabidopsis thaliana, Di-17, results in the development of a hypersensitive response (HR) on the inoculated leaves. In contrast, an HR does not occur when leaves of the TCV-susceptible Di-3 line or the susceptible ecotypes Columbia (Col-0), or Landsberg erecta (Ler) are inoculated. Genetic analysis of progeny from crosses between Di-17 and either Di-3, Col-0 or Ler demonstrates that the development of an HR is regulated by a single dominant nuclear locus, herein designated HRT. Using progeny from a Di-17 x Col-0 cross, HRT was mapped to chromosome 5, where it is tightly linked to the DFR locus. We also demonstrate that a variety of resistance-associated phenomena, including the TCV-induced accumulation of salicylic acid, camalexin and autofluorescent cell-wall material, correlate with the HR, suggesting the possibility that HRT is required for their activation.
-
resistance and susceptible responses of arabidopsis thaliana to Turnip Crinkle Virus
Phytopathology, 1993Co-Authors: Apos D Dempsey, Kristin K Wobbe, Maris Amick, Daniel F KlessigAbstract:We describe the first system in which a hypersensitive response (HR) is observed after viral infection of Arabidopsis thaliana. Most ecotypes of Arabidopsis are highly susceptible to Turnip Crinkle Virus (TCV); however, we developed two lines from the ecotype Dijon that exhibit dramatic differences in TCV susceptibility. Inoculation of the resistant line, Di-17, resulted in necrotic lesion formation on the inoculated leaves, Virus was restricted to these lesions, and no disease symptoms were observed on the uninoculated portions of most plants. Genes encoding the acidic pathogenesis-related (PR) proteins PR-1, PR-2, and PR-5 and the basic form of PR-3 were induced rapidly in the inoculated leaves, whereas upper, uninoculated leaves accumulated mRNA for these genes at slightly later times and to lower levels [...]
