scholarly journals Transient Coexpression of Individual Genes Encoded by the Triple Gene Block of Potato mop-top virus Reveals Requirements for TGBp1 Trafficking

2004 ◽  
Vol 17 (8) ◽  
pp. 921-930 ◽  
Author(s):  
Andrey A. Zamyatnin ◽  
Andrey G. Solovyev ◽  
Eugene I. Savenkov ◽  
Anna Germundsson ◽  
Maria Sandgren ◽  
...  
Keyword(s):  
Cell Wall ◽  
Fluorescent Protein ◽  
Triple Gene Block ◽  
Terminal Region ◽  
Virus Movement ◽  
Cell Periphery ◽  
Movement Proteins ◽  
Gene Block ◽  
Potato Mop Top Virus ◽  
Green Fluorescent

TGBp1, TGBp2, and TGBp3, three plant virus movement proteins encoded by the “triple gene block” (TGB), may act in concert to facilitate cell-to-cell transport of viral RNA genomes. Transient expression of Potato mop-top virus (genus Pomovirus) movement proteins was used as a model to reconstruct interactions between TGB proteins. In bombarded epidermal cells of Nicotiana benthamiana, green fluorescent protein (GFP)-TGBp1 was distributed uniformly. However, in the presence of TGBp2 and TGBp3, GFP-TGBp1 was directed to intermediate bodies at the cell periphery, and to cell wall-embedded punctate bodies. Moreover, GFP-TGBp1 migrated into cells immediately adjacent to the bombarded cell. These data suggest that TGBp2 and TGBp3 mediate transport of GFP-TGBp1 to and through plasmodesmata. Mutagenesis of TGBp1 suggested that the NTPase and helicase activities of TGBp1 were not required for its transport to intermediate bodies directed by TGBp2 and TGBp3, but these activities were essential for the protein association with cell wall-embedded punctate bodies and translocation of TGBp1 to neighboring cells. The C-terminal region of TGBp1 was critical for trafficking mediated by TGBp2 and TGBp3. Mutation analysis also suggested an involvement of the TGBp2 C-terminal region in interactions with TGBp1.

scholarly journals Expression, localization and effects on virulence of the cysteine-rich 8 kDa protein of Potato mop-top virus

2005 ◽  
Vol 86 (10) ◽  
pp. 2879-2889 ◽  
Author(s):  
N. I. Lukhovitskaya ◽  
N. E. Yelina ◽  
A. A. Zamyatnin ◽  
M. V. Schepetilnikov ◽  
A. G. Solovyev ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Fluorescent Protein ◽  
Triple Gene Block ◽  
Potato Virus X ◽  
Host Responses ◽  
Reading Frame ◽  
Movement Proteins ◽  
Gene Block ◽  
Potato Mop Top Virus ◽  
Green Fluorescent

Potato mop-top virus (PMTV) RNA3 contains a triple gene block (TGB) encoding viral movement proteins and an open reading frame for a putative 8 kDa cysteine-rich protein (CRP). In this study, PMTV CRP was shown to be expressed in the course of virus infection, and a PMTV CRP-specific subgenomic RNA was mapped. CRP has previously been shown to be dispensable for infection of PMTV in Nicotiana benthamiana. In this study, PMTV CRP was found to increase the severity of disease symptoms when expressed from Potato virus X or Tobacco mosaic virus in N. benthamiana and Nicotiana tabacum, suggesting that the protein affects virulence of the virus or might suppress a host defence mechanism. However, PMTV CRP did not show RNA silencing suppression activity in three assays. Host responses to the PMTV CRP expression from different viral genomes ranged from an absence of response to extreme resistance at a single cell level and were dependent on the viral genome. These findings emphasized involvement of viral proteins and/or virus-induced cell components in the plant reaction to CRP. PMTV CRP was predicted to possess a transmembrane segment. CRP fused to the green fluorescent protein was associated with endoplasmic reticulum-derived membranes and induced dramatic rearrangements of the endoplasmic reticulum structure, which might account for protein functions as a virulence factor of the virus.

scholarly journals P42 Movement Protein of Beet necrotic yellow vein virus Is Targeted by the Movement Proteins P13 and P15 to Punctate Bodies Associated with Plasmodesmata

2000 ◽  
Vol 13 (5) ◽  
pp. 520-528 ◽  
Author(s):  
M. Erhardt ◽  
M. Morant ◽  
C. Ritzenthaler ◽  
C. Stussi-Garaud ◽  
H. Guilley ◽  
...  
Keyword(s):  
Cell Wall ◽  
Fluorescent Protein ◽  
Triple Gene Block ◽  
Point Mutations ◽  
Cell Movement ◽  
Leading Edge ◽  
Yellow Vein ◽  
Body Formation ◽  
Movement Proteins ◽  
Gene Block

Cell-to-cell movement of Beet necrotic yellow vein virus (BNYVV) is driven by a set of three movement proteins—P42, P13, and P15—organized into a triple gene block (TGB) on viral RNA 2. The first TGB protein, P42, has been fused to the green fluorescent protein (GFP) and fusion proteins between P42 and GFP were expressed from a BNYVV RNA 3-based replicon during virus infection. GFP-P42, in which the GFP was fused to the P42 N terminus, could drive viral cell-to-cell movement when the copy of the P42 gene on RNA 2 was disabled but the C-terminal fusion P42-GFP could not. Confocal microscopy of epidermal cells of Chenopodium quinoa near the leading edge of the infection revealed that GFP-P42 localized to punctate bodies apposed to the cell wall whereas free GFP, expressed from the replicon, was distributed uniformly throughout the cytoplasm. The punctate bodies sometimes appeared to traverse the cell wall or to form pairs of disconnected bodies on each side. The punctate bodies co-localized with callose, indicating that they are associated with plasmodesmata-rich regions such as pit fields. Point mutations in P42 that inhibited its ability to drive cell-to-cell movement also inhibited GFP-P42 punctate body formation. GFP-P42 punctate body formation was dependent on expression of P13 and P15 during the infection, indicating that these proteins act together or sequentially to localize P42 to the plasmodesmata.

scholarly journals Cell-to-Cell Movement of Potato virus X: The Role of p12 and p8 Encoded by the Second and Third Open Reading Frames of the Triple Gene Block

2001 ◽  
Vol 14 (10) ◽  
pp. 1158-1167 ◽  
Author(s):  
Atsushi Tamai ◽  
Tetsuo Meshi
Keyword(s):  
Potato Virus ◽  
Fluorescent Protein ◽  
Microprojectile Bombardment ◽  
Triple Gene Block ◽  
Cell Movement ◽  
Potato Virus X ◽  
Open Reading Frames ◽  
Gene Block ◽  
Infected Cells ◽  
Green Fluorescent

Potato virus X (PVX) requires three proteins, p25, p12, and p8, encoded by the triple gene block plus the coat protein (CP) for cell-to-cell movement. When each of these proteins was co-expressed with a cytosolic green fluorescent protein (GFP) in the epidermal cells of Nicotiana benthamiana by the microprojectile bombardment-mediated gene delivery method, only p12 enhanced diffusion of co-expressed GFP, indicating an ability to alter plasmodesmal permeability. p25, p12, and CP, expressed transiently in the initially infected cells, transcomplemented the corresponding movement-defective mutants to spread through two or more cell boundaries. Thus, these proteins probably move from cell to cell with the genomic RNA. In contrast, p8 only functioned intracellularly and was not absolutely required for cell-to-cell movement. Since overexpression of p12 overcame the p8 deficiency, p8 appears to facilitate the functioning of p12, presumably by mediating its intracellular trafficking. Considering the likelihood that p12 and p8 are membrane proteins, it is suggested that intercellular as well as intracellular movement of PVX involves a membrane-mediated process.

scholarly journals Interactions of the TGB1 Protein during Cell-to-Cell Movement of Barley Stripe Mosaic Virus

2001 ◽  
Vol 75 (18) ◽  
pp. 8712-8723 ◽  
Author(s):  
Diane M. Lawrence ◽  
A. O. Jackson
Keyword(s):  
Subcellular Localization ◽  
Mosaic Virus ◽  
Fluorescent Protein ◽  
Triple Gene Block ◽  
Cell Movement ◽  
Barley Stripe Mosaic Virus ◽  
Helicase Domain ◽  
Chenopodium Amaranticolor ◽  
Gene Block ◽  
Green Fluorescent

ABSTRACT We have recently used a green fluorescent protein (GFP) fusion to the γb protein of Barley stripe mosaic virus (BSMV) to monitor cell-to-cell and systemic virus movement. The γb protein is involved in expression of the triple gene block (TGB) proteins encoded by RNAβ but is not essential for cell-to-cell movement. The GFP fusion appears not to compromise replication or movement substantially, and mutagenesis experiments demonstrated that the three most abundant TGB-encoded proteins, βb (TGB1), βc (TGB3), and βd (TGB2), are each required for cell-to-cell movement (D. M. Lawrence and A. O. Jackson, Mol. Plant Pathol. 2:65–75, 2001). We have now extended these analyses by engineering a fusion of GFP to TGB1 to examine the expression and interactions of this protein during infection. BSMV derivatives containing the TGB1 fusion were able to move from cell to cell and establish local lesions in Chenopodium amaranticolor and systemic infections of Nicotiana benthamiana and barley. In these hosts, the GFP-TGB1 fusion protein exhibited a temporal pattern of expression along the advancing edge of the infection front. Microscopic examination of the subcellular localization of the GFP-TGB1 protein indicated an association with the endoplasmic reticulum and with plasmodesmata. The subcellular localization of the TGB1 protein was altered in infections in which site-specific mutations were introduced into the six conserved regions of the helicase domain and in mutants unable to express the TGB2 and/or TGB3 proteins. These results are compatible with a model suggesting that movement requires associations of the TGB1 protein with cytoplasmic membranes that are facilitated by the TGB2 and TGB3 proteins.

scholarly journals RNA Helicase Activity of the Plant Virus Movement Proteins Encoded by the First Gene of the Triple Gene Block

Virology ◽  
2002 ◽  
Vol 296 (2) ◽  
pp. 321-329 ◽  
Author(s):  
N.O. Kalinina ◽  
D.V. Rakitina ◽  
A.G. Solovyev ◽  
J. Schiemann ◽  
S.Yu. Morozov
Keyword(s):  
Plant Virus ◽  
Triple Gene Block ◽  
Rna Helicase ◽  
Virus Movement ◽  
Helicase Activity ◽  
Movement Proteins ◽  
Gene Block

scholarly journals Actin Cytoskeleton and Golgi Involvement in Barley stripe mosaic virus Movement and Cell Wall Localization of Triple Gene Block Proteins

2013 ◽  
Vol 29 (1) ◽  
pp. 17-30 ◽  
Author(s):  
Hyoun-Sub Lim ◽  
Mi Yeon Lee ◽  
Jae Sun Moon ◽  
Jung-Kyung Moon ◽  
Yong-Man Yu ◽  
...  
Keyword(s):  
Cell Wall ◽  
Actin Cytoskeleton ◽  
Mosaic Virus ◽  
Triple Gene Block ◽  
Barley Stripe Mosaic Virus ◽  
Virus Movement ◽  
Gene Block

scholarly journals Arg-16 and Arg-21 in the N-terminal region of the triple-gene-block protein 1 of Bamboo mosaic virus are essential for virus movement

2004 ◽  
Vol 85 (1) ◽  
pp. 251-259 ◽  
Author(s):  
Ming-Kuem Lin ◽  
Ban-Yang Chang ◽  
Jia-Teh Liao ◽  
Na-Sheng Lin ◽  
Yau-Heiu Hsu
Keyword(s):  
Mosaic Virus ◽  
Triple Gene Block ◽  
Terminal Region ◽  
Virus Movement ◽  
Gene Block ◽  
Triple Gene Block Protein

scholarly journals Molecular biology of potexviruses: recent advances

2007 ◽  
Vol 88 (6) ◽  
pp. 1643-1655 ◽  
Author(s):  
Jeanmarie Verchot-Lubicz ◽  
Chang-Ming Ye ◽  
Devinka Bamunusinghe
Keyword(s):  
Gene Silencing ◽  
Rna Synthesis ◽  
Triple Gene Block ◽  
Potato Virus X ◽  
Future Research ◽  
Virus Movement ◽  
Suppressor Activity ◽  
Gene Block ◽  
Recent Advances

Recent advances in potexvirus research have produced new models describing virus replication, cell-to-cell movement, encapsidation, R gene-mediated resistance and gene silencing. Interactions between distant RNA elements are a central theme in potexvirus replication. The 5′ non-translated region (NTR) regulates genomic and subgenomic RNA synthesis and encapsidation, as well as virus plasmodesmal transport. The 3′ NTR regulates both plus- and minus-strand RNA synthesis. How the triple gene-block proteins interact for virus movement is still elusive. As the potato virus X (PVX) TGBp1 protein gates plasmodesmata, regulates virus translation and is a suppressor of RNA silencing, further research is needed to determine how these properties contribute to propelling virus through the plasmodesmata. Specifically, TGBp1 suppressor activity is required for virus movement, but how the silencing machinery relates to plasmodesmata is not known. The TGBp2 and TGBp3 proteins are endoplasmic reticulum (ER)-associated proteins required for virus movement. TGBp2 associates with ER-derived vesicles that traffic along the actin network. Future research will determine whether the virus-induced vesicles are cytopathic structures regulating events along the ER or are vehicles carrying virus to the plasmodesmata for transfer into neighbouring cells. Efforts to assemble virions in vitro identified a single-tailed particle (STP) comprising RNA, coat protein (CP) and TGBp1. It has been proposed that TGBp1 aids in transport of virions or STP between cells and ensures translation of RNA in the receiving cells. PVX is also a tool for studying Avr–R gene interactions and gene silencing in plants. The PVX CP is the elicitor for the Rx gene. Recent reports of the PVX CP reveal how CP interacts with the Rx gene product.

scholarly journals The Potato Virus X TGBp2 Protein Plays Dual Functional Roles in Viral Replication and Movement

2018 ◽  
Vol 93 (5) ◽  
Author(s):  
Xiaoyun Wu ◽  
Jiahui Liu ◽  
Mengzhu Chai ◽  
Jinhui Wang ◽  
Dalong Li ◽  
...  
Keyword(s):  
Triple Gene Block ◽  
Potato Virus X ◽  
Plant Viruses ◽  
Open Reading Frames ◽  
Movement Proteins ◽  
Gene Block ◽  
Functional Roles ◽  
Viral Rdrp ◽  
Dual Functional ◽  
Intercellular Movement

ABSTRACTPlant viruses usually encode one or more movement proteins (MP) to accomplish their intercellular movement. A group of positive-strand RNA plant viruses requires three viral proteins (TGBp1, TGBp2, and TGBp3) that are encoded by an evolutionarily conserved genetic module of three partially overlapping open reading frames (ORFs), termed the triple gene block (TGB). However, how these three viral movement proteins function cooperatively in viral intercellular movement is still elusive. Using a novelin vivodouble-stranded RNA (dsRNA) labeling system, we showed that the dsRNAs generated by potato virus X (PVX) RNA-dependent RNA polymerase (RdRp) are colocalized with viral RdRp, which are further tightly covered by “chain mail”-like TGBp2 aggregates and localizes alongside TGBp3 aggregates. We also discovered that TGBp2 interacts with the C-terminal domain of PVX RdRp, and this interaction is required for the localization of TGBp3 and itself to the RdRp/dsRNA bodies. Moreover, we reveal that the central and C-terminal hydrophilic domains of TGBp2 are required to interact with viral RdRp. Finally, we demonstrate that knockout of the entire TGBp2 or the domain involved in interacting with viral RdRp attenuates both PVX replication and movement. Collectively, these findings suggest that TGBp2 plays dual functional roles in PVX replication and intercellular movement.IMPORTANCEMany plant viruses contain three partially overlapping open reading frames (ORFs), termed the triple gene block (TGB), for intercellular movement. However, how the corresponding three proteins coordinate their functions remains obscure. In the present study, we provided multiple lines of evidence supporting the notion that PVX TGBp2 functions as the molecular adaptor bridging the interaction between the RdRp/dsRNA body and TGBp3 by forming “chain mail”-like structures in the RdRp/dsRNA body, which can also enhance viral replication. Taken together, our results provide new insights into the replication and movement of PVX and possibly also other TGB-containing plant viruses.

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