scholarly journals The Role of the Cucumber mosaic virus 2b Protein in Viral Movement and Symptom Induction

2009 ◽  
Vol 22 (6) ◽  
pp. 642-654 ◽  
Author(s):  
Mathew Lewsey ◽  
Monique Surette ◽  
Fiona C. Robertson ◽  
Heiko Ziebell ◽  
Sun Hee Choi ◽  
...  
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Wild Type Virus ◽  
Type Virus ◽  
Wild Type ◽  
Nuclear Localization Signals ◽  
Systemic Movement ◽  
Terminal Domain ◽  
2B Protein ◽  
Important Symptom

The Cucumber mosaic virus (CMV) 2b protein is a counter-defense factor and symptom determinant. Conserved domains in the 2b protein sequence were mutated in the 2b gene of strain Fny-CMV. The effects of these mutations were assessed by infection of Nicotiana tabacum, N. benthamiana, and Arabidopsis thaliana (ecotype Col-0) with mutant viruses and by expression of mutant 2b transgenes in A. thaliana. We confirmed that two nuclear localization signals were required for symptom induction and found that the N-terminal domain was essential for symptom induction. The C-terminal domain and two serine residues within a putative phosphorylation domain modulated symptom severity. Further infection studies were conducted using Fny-CMVΔ2b, a mutant that cannot express the 2b protein and that induces no symptoms in N. tabacum, N. benthamiana, or A. thaliana ecotype Col-0. Surprisingly, in plants of A. thaliana ecotype C24, Fny-CMVΔ2b induced severe symptoms similar to those induced by the wild-type virus. However, C24 plants infected with the mutant virus recovered from disease while those infected with the wild-type virus did not. Expression of 2b transgenes from either Fny-CMV or from LS-CMV (a mild strain) in Col-0 plants enhanced systemic movement of Fny-CMVΔ2b and permitted symptom induction by Fny-CMVΔ2b. Taken together, the results indicate that the 2b protein itself is an important symptom determinant in certain hosts. However, they also suggest that the protein may somehow synergize symptom induction by other CMV-encoded factors.

scholarly journals Functional analysis of the Cucumber mosaic virus 2b protein: pathogenicity and nuclear localization

2004 ◽  
Vol 85 (10) ◽  
pp. 3135-3147 ◽  
Author(s):  
Yongzeng Wang ◽  
Tzvi Tzfira ◽  
Victor Gaba ◽  
Vitaly Citovsky ◽  
Peter Palukaitis ◽  
...  
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Nuclear Localization ◽  
Zucchini Yellow Mosaic Virus ◽  
Yellow Mosaic Virus ◽  
Silencing Suppressor ◽  
Nuclear Localization Signals ◽  
Systemic Movement ◽  
2B Protein ◽  
Function Expression

The 2b protein encoded by Cucumber mosaic virus (CMV) has been shown to be a silencing suppressor and pathogenicity determinant in solanaceous hosts, but a movement determinant in cucumber. In addition, synergistic interactions between CMV and Zucchini yellow mosaic virus (ZYMV) have been described in several cucurbit species. Here, it was shown that deletion of the 2b gene from CMV prevented extensive systemic movement of the virus in zucchini squash, which could not be complemented by co-infection with ZYMV. Thus, ZYMV expressing a silencing suppressor with a different target could not complement the CMV 2b-specific movement function. Expression of the 2b protein from an attenuated ZYMV vector resulted in a synergistic response, largely restoring infection symptoms of wild-type ZYMV in several cucurbit species. Deletion or alteration of either of two nuclear localization signals (NLSs) did not affect nuclear localization in two assays, but did affect pathogenicity in several cucurbit species, whilst deletion of both NLSs led to loss of nuclear localization. The 2b protein interacted with an Arabidopsis thaliana karyopherin α protein (AtKAPα) in the yeast two-hybrid system, as did each of the two single NLS-deletion mutants. However, 2b protein containing a deletion of both NLSs was unable to interact with AtKAPα. These data suggest that the 2b protein localizes to the nucleus by using the karyopherin α-mediated system, but demonstrate that nuclear localization was insufficient for enhancement of the 2b-mediated pathogenic response in cucurbit hosts. Thus, the sequences corresponding to the two NLSs must have another role leading to pathogenicity enhancement.

scholarly journals Virulence and Differential Local and Systemic Spread of Cucumber mosaic virus in Tobacco are Affected by the CMV 2b Protein

2002 ◽  
Vol 15 (7) ◽  
pp. 647-653 ◽  
Author(s):  
Avril J. Soards ◽  
Alex M. Murphy ◽  
Peter Palukaitis ◽  
John P. Carr
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Laser Scanning ◽  
Fluorescent Protein ◽  
Wild Type Virus ◽  
Virus Spread ◽  
Wild Type ◽  
Mesophyll Cells ◽  
Systemic Spread ◽  
2B Protein

A mutant of the Cucumber mosaic virus subgroup IA strain Fny (Fny-CMV) lacking the gene encoding the 2b protein (Fny-CMVΔ2b) induced a symptomless systemic infection in tobacco. Both the accumulation of Fny-CMVΔ2b in inoculated tissue and the systemic movement of the virus appeared to proceed more slowly than for wild-type Fny-CMV. The influence of the 2b protein on virus movement in the inoculated leaf was examined using viral constructs derived from Fny-CMV and Fny-CMVΔ2b expressing the green fluorescent protein. Laser scanning confocal microscopy was used to visualize the movement of these viruses. Whereas the wild-type virus spread between the epidermal cells as well as the mesophyll cells, the mutant virus spread less efficiently through the epidermal layer and moved preferentially through the mesophyll. Thus, the 2b protein of Fny-CMV influences the dynamics of movement of the virus both within the inoculated leaf and through the whole plant. We propose that this altered movement profile of Fny-CMVΔ2b results in the absence of disease symptoms in tobacco.

scholarly journals Wheat streak mosaic virus Coat Protein Deletion Mutants Elicit More Severe Symptoms Than Wild-Type Virus in Multiple Cereal Hosts

2017 ◽  
Vol 30 (12) ◽  
pp. 974-983 ◽  
Author(s):  
Satyanarayana Tatineni ◽  
Christian Elowsky ◽  
Robert A. Graybosch
Keyword(s):  
Amino Acids ◽  
Coat Protein ◽  
Mosaic Virus ◽  
Wheat Streak Mosaic Virus ◽  
Wild Type Virus ◽  
Deletion Mutants ◽  
Major Protein ◽  
Type Virus ◽  
Wild Type ◽  
Genomic Rnas

Previously, we reported that coat protein (CP) of Wheat streak mosaic virus (WSMV) (genus Tritimovirus, family Potyviridae) tolerates deletion of amino acids 36 to 84 for efficient systemic infection of wheat. In this study, we demonstrated that WSMV mutants with deletion of CP amino acids 58 to 84 but not of 36 to 57 induced severe chlorotic streaks and spots, followed by acute chlorosis in wheat, maize, barley, and rye compared with mild to moderate chlorotic streaks and mosaic symptoms by wild-type virus. Deletion of CP amino acids 58 to 84 from the WSMV genome accelerated cell-to-cell movement, with increased accumulation of genomic RNAs and CP, compared with the wild-type virus. Microscopic examination of wheat tissues infected by green fluorescent protein–tagged mutants revealed that infection by mutants lacking CP amino acids 58 to 84 caused degradation of chloroplasts, resulting in acute macroscopic chlorosis. The profile of CP-specific proteins was altered in wheat infected by mutants causing acute chlorosis, compared with mutants eliciting wild-type symptoms. All deletion mutants accumulated CP-specific major protein similarly to that in wild-type virus; however, mutants that elicit acute chlorosis failed to accumulate a 31-kDa minor protein compared with wild-type virus or mutants lacking amino acids 36 to 57. Taken together, these data suggest that deletion of CP amino acids 58 to 84 from the WSMV genome enhanced accumulation of CP and genomic RNA, altered CP-specific protein profiles, and caused severe symptom phenotypes in multiple cereal hosts.

Plants Transformed with a Mutant Alfalfa Mosaic Virus Coat Protein Gene Are Resistant to the Mutant but Not to Wild-Type Virus

Virology ◽  
1994 ◽  
Vol 203 (2) ◽  
pp. 269-276 ◽  
Author(s):  
Peter E.M. Taschner ◽  
Guido Van Marle ◽  
Frans Th. Brederode ◽  
Nilgun E. Tumer ◽  
John F. Bol
Keyword(s):  
Coat Protein ◽  
Mosaic Virus ◽  
Coat Protein Gene ◽  
Protein Gene ◽  
Alfalfa Mosaic Virus ◽  
Wild Type Virus ◽  
Type Virus ◽  
Wild Type ◽  
Virus Coat Protein ◽  
Virus Coat

scholarly journals A Conserved Capsid Protein Surface Domain of Cucumber Mosaic Virus Is Essential for Efficient Aphid Vector Transmission

2002 ◽  
Vol 76 (19) ◽  
pp. 9756-9762 ◽  
Author(s):  
Sijun Liu ◽  
Xiaohua He ◽  
Gyungsoon Park ◽  
Caroline Josefsson ◽  
Keith L. Perry
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Capsid Protein ◽  
Wild Type Virus ◽  
Cdna Clones ◽  
Wild Type ◽  
Vector Transmission ◽  
Aphid Vector

ABSTRACT A prominent feature on the surfaces of virions of Cucumber mosaic virus (CMV) is a negatively charged loop structure (the βH-βI loop). Six of 8 amino acids in this capsid protein loop are highly conserved among strains of CMV and other cucumoviruses. Five of these amino acids were individually changed to alanine or lysine (an amino acid of opposite charge) to create nine mutants (the D191A, D191K, D192A, D192K, L194A, E195A, E195K, D197A, and D197K mutants). Transcripts of cDNA clones were infectious when they were mechanically inoculated onto tobacco, giving rise to symptoms of a mottle-mosaic typical of the wild-type virus (the D191A, D191K, D192A, E195A, E195K, and D197A mutants), a systemic necrosis (the D192K mutant), or an atypical chlorosis with necrotic flecking (the L194A mutant). The mutants formed virions and accumulated to wild-type levels, but eight of the nine mutants were defective in aphid vector transmission. The aspartate-to-lysine mutation at position 197 interfered with infection; the only recovered progeny (the D197K∗ mutant) harbored a second-site mutation (denoted by the asterisk) of alanine to glutamate at position 193, a proximal site in the βH-βI loop. Since the disruption of charged amino acid residues in the βH-βI loop reduces or eliminates vector transmissibility without grossly affecting infectivity or virion formation, we hypothesize that this sequence or structure has been conserved to facilitate aphid vector transmission.

scholarly journals The C-terminal domain of the 2b protein of Cucumber mosaic virus is stabilized by divalent metal ion coordination

2012 ◽  
Vol 38 ◽  
pp. 446-454 ◽  
Author(s):  
Ákos Gellért ◽  
Katalin Nemes ◽  
Katalin Kádár ◽  
Katalin Salánki ◽  
Ervin Balázs
Keyword(s):  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Metal Ion ◽  
Divalent Metal ◽  
Terminal Domain ◽  
2B Protein ◽  
Divalent Metal Ion

scholarly journals Mutations in the N Terminus of the Brome Mosaic Virus Polymerase Affect Genetic RNA-RNA Recombination

1998 ◽  
Vol 72 (11) ◽  
pp. 9192-9200 ◽  
Author(s):  
M. Figlerowicz ◽  
P. D. Nagy ◽  
N. Tang ◽  
C. C. Kao ◽  
J. J. Bujarski
Keyword(s):  
Homologous Recombination ◽  
Mosaic Virus ◽  
Chenopodium Quinoa ◽  
Brome Mosaic Virus ◽  
Wild Type Virus ◽  
Rna Recombination ◽  
Wild Type ◽  
Nonhomologous Recombination ◽  
Terminal Domain ◽  
N Terminus

ABSTRACT Previously, we have observed that mutations in proteins 1a and 2a, the two virally encoded components of the brome mosaic virus (BMV) replicase, can affect the frequency of recombination and the locations of RNA recombination sites (P. D. Nagy, A. Dzianott, P. Ahlquist, and J. J. Bujarski, J. Virol. 69:2547–2556, 1995; M. Figlerowicz, P. D. Nagy, and J. J. Bujarski, Proc. Natl. Acad. Sci. USA 94:2073–2078, 1997). Also, it was found before that the N-terminal domain of 2a, the putative RNA polymerase protein, participates in the interactions between 1a and 2a (C. C. Kao, R. Quadt, R. P. Hershberger, and P. Ahlquist, J. Virol. 66:6322–6329, 1992; E. O’Reilly, J. Paul, and C. C. Kao, J. Virol. 71:7526–7532, 1997). In this work, we examine how mutations within the N terminus of 2a influence RNA recombination in BMV. Because of the likely electrostatic character of 1a-2a interactions, five 2a mutants, MF1 to MF5, were generated by replacing clusters of acidic amino acids with their neutral counterparts. MF2 and MF5 retained nearly wild-type levels of 1a-2a interaction and were infectious inChenopodium quinoa. However, compared to that in wild-type virus, the frequency of nonhomologous recombination in both MF2 and MF5 was markedly decreased. Only in MF2 was the frequency of homologous recombination reduced and the occurrence of imprecise homologous recombination increased. In MF5 there was also a 3′ shift in the positions of homologous crossovers. The observed effects of MF2 and MF5 reveal that the 2a N-terminal domain participates in different ways in homologous and in nonhomologous BMV RNA recombination. This work maps specific locations within the N terminus involved in 1a-2a interaction and in recombination and further suggests that the mechanisms of the two types of crossovers in BMV are different.

scholarly journals In Vitro Transcripts of Wild-Type and Fluorescent Protein-Tagged Triticum mosaic virus (Family Potyviridae) are Biologically Active in Wheat

2015 ◽  
Vol 105 (11) ◽  
pp. 1496-1505 ◽  
Author(s):  
Satyanarayana Tatineni ◽  
Anthony J. McMechan ◽  
Melissa Bartels ◽  
Gary L. Hein ◽  
Robert A. Graybosch
Keyword(s):  
Mosaic Virus ◽  
Fluorescent Protein ◽  
Wild Type Virus ◽  
Progeny Virus ◽  
Cdna Clones ◽  
Type Virus ◽  
Wild Type ◽  
Wheat Seedlings ◽  
In Vitro Transcripts

Triticum mosaic virus (TriMV) (genus Poacevirus, family Potyviridae) is a recently described eriophyid mite-transmitted wheat virus. In vitro RNA transcripts generated from full-length cDNA clones of TriMV proved infectious on wheat. Wheat seedlings inoculated with in vitro transcripts elicited mosaic and mottling symptoms similar to the wild-type virus, and the progeny virus was efficiently transmitted by wheat curl mites, indicating that the cloned virus retained pathogenicity, movement, and wheat curl mite transmission characteristics. A series of TriMV-based expression vectors was constructed by engineering a green fluorescent protein (GFP) or red fluorescent protein (RFP) open reading frame with homologous NIa-Pro cleavage peptides between the P1 and HC-Pro cistrons. We found that GFP-tagged TriMV with seven or nine amino acid cleavage peptides efficiently processed GFP from HC-Pro. TriMV-GFP vectors were stable in wheat for more than 120 days and for six serial passages at 14-day intervals by mechanical inoculation and were transmitted by wheat curl mites similarly to the wild-type virus. Fluorescent protein-tagged TriMV was observed in wheat leaves, stems, and crowns. The availability of fluorescent protein-tagged TriMV will facilitate the examination of virus movement and distribution in cereal hosts and the mechanisms of cross protection and synergistic interactions between TriMV and Wheat streak mosaic virus.

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