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 Compensatory Capsid Protein Mutations in Cucumber Mosaic Virus Confer Systemic Infectivity in Squash (Cucurbita pepo)

2006 ◽  
Vol 80 (15) ◽  
pp. 7740-7743 ◽  
Author(s):  
Jeremy R. Thompson ◽  
Stephanie Doun ◽  
Keith L. Perry
Keyword(s):  
Amino Acid ◽  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Capsid Protein ◽  
Cucurbita Pepo ◽  
Single Amino Acid ◽  
Amino Acid Substitutions ◽  
Wild Type ◽  
Wild Type Phenotype ◽  
Compensatory Mutations

ABSTRACT Cucumber mosaic virus (CMV) systemically infects both tobacco and zucchini squash. CMV capsid protein loop mutants with single-amino-acid substitutions are unable to systemically infect squash, but they revert to a wild-type phenotype in the presence of an additional, specific single-site substitution. The D118A, T120A, D192A, and D197A loop mutants reverted to a wild-type phenotype but did so in combination with P56S, P77L, A162V, and I53F or T124I mutations, respectively. The possible effect of these compensatory mutations on other, nonsystemically infecting loop mutants was tested with the F117A mutant and found to be neutral, thus indicating a specificity to the observed changes.

scholarly journals The Rate of Cell-to-Cell Movement in Squash of Cucumber Mosaic Virus Is Affected by Sequences of the Capsid Protein

1999 ◽  
Vol 12 (7) ◽  
pp. 628-632 ◽  
Author(s):  
Sek-Man Wong ◽  
Sharon Swee-Chin Thio ◽  
Michael H. Shintaku ◽  
Peter Palukaitis
Keyword(s):  
Amino Acids ◽  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Capsid Protein ◽  
Cell Movement ◽  
Systemic Infection ◽  
Long Distance ◽  
Local Movement ◽  
Long Distance Movement

The M strain of cucumber mosaic virus (CMV) does not infect squash plants systemically and moves very slowly in inoculated cotyledons. Systemic infection and an increase in the rate of local movement were observed when amino acids 129 or 214 of the M-CMV capsid protein (CP) were altered to those present in the Fny strain of CMV. While the opposite alterations to the CP of Fny-CMV inhibited systemic infection of squash, they did not show the same effects on the rates of both cell-to-cell and long-distance movement. However, the ability of CMV to infect squash systemically was affected by the rate of cell-to-cell movement.

scholarly journals Identification of amino acid sequences determining interaction between the cucumber mosaic virus-encoded 2a polymerase and 3a movement proteins

2007 ◽  
Vol 88 (12) ◽  
pp. 3445-3451 ◽  
Author(s):  
Min Sook Hwang ◽  
Kyung Nam Kim ◽  
Jeong Hyun Lee ◽  
Young In Park
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Cucumber Mosaic Virus ◽  
Mosaic Virus ◽  
Critical Role ◽  
Amino Acid Sequences ◽  
Multiple Sequence ◽  
Movement Proteins ◽  
Gdd Motif

The cucumber mosaic virus (CMV)-encoded 3a movement protein (MP) is indispensable for CMV movement in plants. We have previously shown that MP interacts directly with the CMV-encoded 2a polymerase protein in vitro. Here, we further dissected this interaction and determined the amino acid sequences that are responsible for the MP and 2a polymerase protein interaction. Both the N-terminal 21 amino acids and the central GDD motif of the 2a polymerase protein were important for interacting with the MP. Although each of the regions alone was sufficient for the interaction with MP, quantitative yeast two-hybrid analyses showed that they acted synergistically to enhance the binding affinity. The MP N-terminal 20 amino acids were sufficient for interacting with the 2a polymerase protein, and the serine residue at position 14 played a critical role in the interaction. Multiple sequence alignment showed that the 2a protein interacting regions and the serine at position 14 in the MP are highly conserved among subgroup I and II CMV isolates.

scholarly journals Amino Acids in the Capsid Protein of Tomato Yellow Leaf Curl Virus That Are Crucial for Systemic Infection, Particle Formation, and Insect Transmission

1998 ◽  
Vol 72 (12) ◽  
pp. 10050-10057 ◽  
Author(s):  
E. Noris ◽  
A. M. Vaira ◽  
P. Caciagli ◽  
V. Masenga ◽  
B. Gronenborn ◽  
...  
Keyword(s):  
Amino Acid ◽  
Capsid Protein ◽  
Tomato Yellow Leaf ◽  
Single Amino Acid ◽  
Wild Type Virus ◽  
Yellow Leaf ◽  
Wild Type ◽  
Insect Transmission ◽  
Leaf Curl Virus ◽  
Leaf Curl

ABSTRACT A functional capsid protein (CP) is essential for host plant infection and insect transmission in monopartite geminiviruses. We studied two defective genomic DNAs of tomato yellow leaf curl virus (TYLCV), Sic and SicRcv. Sic, cloned from a field-infected tomato, was not infectious, whereas SicRcv, which spontaneously originated from Sic, was infectious but not whitefly transmissible. A single amino acid change in the CP was found to be responsible for restoring infectivity. When the amino acid sequences of the CPs of Sic and SicRcv were compared with that of a closely related wild-type virus (TYLCV-Sar), differences were found in the following positions: 129 (P in Sic and SicRcv, Q in Sar), 134 (Q in Sic and Sar, H in SicRcv) and 152 (E in Sic and SicRcv, D in Sar). We constructed TYLCV-Sar variants containing the eight possible amino acid combinations in those three positions and tested them for infectivity and transmissibility. QQD, QQE, QHD, and QHE had a wild-type phenotype, whereas PHD and PHE were infectious but nontransmissible. PQD and PQE mutants were not infectious; however, they replicated and accumulated CP, but not virions, in Nicotiana benthamiana leaf discs. The Q129P replacement is a nonconservative change, which may drastically alter the secondary structure of the CP and affect its ability to form the capsid. The additional Q134H change, however, appeared to compensate for the structural modification. Sequence comparisons among whitefly-transmitted geminiviruses in terms of the CP region studied showed that combinations other than QQD are present in several cases, but never with a P129.

scholarly journals Characterization and Construction of Functional cDNA Clones of Pariacoto Virus, the First Alphanodavirus Isolated outside Australasia

2000 ◽  
Vol 74 (11) ◽  
pp. 5123-5132 ◽  
Author(s):  
Karyn N. Johnson ◽  
Jean-Louis Zeddam ◽  
L. Andrew Ball
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Capsid Protein ◽  
Cultured Cells ◽  
Geographic Origin ◽  
Amino Acid Sequences ◽  
Cdna Clones ◽  
Homologous Proteins ◽  
Genomic Rnas ◽  
Rna Genome

ABSTRACT Pariacoto virus (PaV) was recently isolated in Peru from the Southern armyworm (Spodoptera eridania). PaV particles are isometric, nonenveloped, and about 30 nm in diameter. The virus has a bipartite RNA genome and a single major capsid protein with a molecular mass of 39.0 kDa, features that support its classification as aNodavirus. As such, PaV is the firstAlphanodavirus to have been isolated from outside Australasia. Here we report that PaV replicates in wax moth larvae and that PaV genomic RNAs replicate when transfected into cultured baby hamster kidney cells. The complete nucleotide sequences of both segments of the bipartite RNA genome were determined. The larger genome segment, RNA1, is 3,011 nucleotides long and contains a 973-amino-acid open reading frame (ORF) encoding protein A, the viral contribution to the RNA replicase. During replication, a 414-nucleotide long subgenomic RNA (RNA3) is synthesized which is coterminal with the 3′ end of RNA1. RNA3 contains a small ORF which could encode a protein of 90 amino acids similar to the B2 protein of other alphanodaviruses. RNA2 contains 1,311 nucleotides and encodes the 401 amino acids of the capsid protein precursor α. The amino acid sequences of the PaV capsid protein and the replicase subunit share 41 and 26% identity with homologous proteins of Flock house virus, the best characterized of the alphanodaviruses. These and other sequence comparisons indicate that PaV is evolutionarily the most distant of the alphanodaviruses described to date, consistent with its novel geographic origin. Although the PaV capsid precursor is cleaved into the two mature capsid proteins β and γ, the amino acid sequence at the cleavage site, which is Asn/Ala in all other alphanodaviruses, is Asn/Ser in PaV. To facilitate the investigation of PaV replication in cultured cells, we constructed plasmids that transcribed full-length PaV RNAs with authentic 5′ and 3′ termini. Transcription of these plasmids in cells recreated the replication of PaV RNA1 and RNA2, synthesis of subgenomic RNA3, and translation of viral proteins A and α.

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.

scholarly journals Alphavirus Nucleocapsid Protein Contains a Putative Coiled Coil α-Helix Important for Core Assembly

2001 ◽  
Vol 75 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Rushika Perera ◽  
Katherine E. Owen ◽  
Timothy L. Tellinghuisen ◽  
Alexander E. Gorbalenya ◽  
Richard J. Kuhn
Keyword(s):  
Amino Acid ◽  
Capsid Protein ◽  
Coiled Coil ◽  
Terminal Region ◽  
Wild Type Virus ◽  
Wild Type ◽  
Particle Assembly ◽  
In Vitro Assembly ◽  
Α Helix

ABSTRACT The alphavirus nucleocapsid core is formed through the energetic contributions of multiple noncovalent interactions mediated by the capsid protein. This protein consists of a poorly conserved N-terminal region of unknown function and a C-terminal conserved autoprotease domain with a major role in virion formation. In this study, an 18-amino-acid conserved region, predicted to fold into an α-helix (helix I) and embedded in a low-complexity sequence enriched with basic and Pro residues, has been identified in the N-terminal region of the alphavirus capsid proteins. In Sindbis virus, helix I spans residues 38 to 55 and contains three conserved leucine residues, L38, L45, and L52, conforming to the heptad amino acid organization evident in leucine zipper proteins. Helix I consists of an N-terminally truncated heptad and two complete heptad repeats with β-branched residues and conserved leucine residues occupying the a andd positions of the helix, respectively. Complete or partial deletion of helix I, or single-site substitutions at the conserved leucine residues (L45 and L52), caused a significant decrease in virus replication. The mutant viruses were more sensitive to elevated temperature than wild-type virus. These mutant viruses also failed to accumulate cores in the cytoplasm of infected cells, although they did not have defects in protein translation or processing. Analysis of these mutants using an in vitro assembly system indicated that the majority were defective in core particle assembly. Furthermore, mutant proteins showed a trans-dominant negative phenotype in in vitro assembly reactions involving mutant and wild-type proteins. We propose that helix I plays a central role in the assembly of nucleocapsid cores through coiled coil interactions. These interactions may stabilize subviral intermediates formed through the interactions of the C-terminal domain of the capsid protein and the genomic RNA and contribute to the stability of the virion.

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.

Sign in / Sign up

Export Citation Format

Share Document