scholarly journals TIP, A Novel Host Factor Linking Callose Degradation with the Cell-to-Cell Movement of Potato virus X

2003 ◽  
Vol 16 (2) ◽  
pp. 132-140 ◽  
Author(s):  
Ingela Fridborg ◽  
Jef Grainger ◽  
Anthony Page ◽  
Mark Coleman ◽  
Kim Findlay ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Potato Virus ◽  
Triple Gene Block ◽  
Cell Movement ◽  
Potato Virus X ◽  
Host Factor ◽  
Size Exclusion ◽  
Cell Periphery ◽  
Viral Movement Protein ◽  
Gene Block

The cell-to-cell movement of Potato virus X (PVX) requires four virus-encoded proteins, the triple gene block (TGB) proteins (TGB25K, TGB12K, and TGB8K) and the coat protein. TGB12K increases the plasmodesmal size exclusion limit (SEL) and may, therefore, interact directly with components of the cell wall or with plant proteins associated with bringing about this change. A yeast two-hybrid screen using TGB12K as bait identified three TGB12K-interacting proteins (TIP1, TIP2, and TIP3). All three TIPs interacted specifically with TGB12K but not with TGB25K or TGB8K. Similarly, all three TIPs interacted with β-1,3-glucanase, the enzyme that may regulate plasmodesmal SEL through callose degradation. Sequence analyses revealed that the TIPs encode very similar proteins and that TIP1 corresponds to the tobacco ankyrin repeat-containing protein HBP1. A TIP1::GFP fusion protein localized to the cytoplasm. Coexpression of this fusion protein with TGB12K induced cellular changes manifested as deposits of additional cytoplasm at the cell periphery. This work reports a direct link between a viral movement protein required to increase plasmodesmal SEL and a host factor that has been implicated as a key regulator of plasmodesmal SEL. We propose that the TIPs are susceptibility factors that modulate the plasmodesmal SEL.

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 Experimental and bioinformatic evidence that raspberry leaf blotch emaravirus P4 is a movement protein of the 30K superfamily

2013 ◽  
Vol 94 (9) ◽  
pp. 2117-2128 ◽  
Author(s):  
Chulang Yu ◽  
David G. Karlin ◽  
Yuwen Lu ◽  
Kathryn Wright ◽  
Jianping Chen ◽  
...  
Keyword(s):  
Movement Protein ◽  
Triple Gene Block ◽  
Tobacco Rattle Virus ◽  
Cell Movement ◽  
Potato Virus X ◽  
Plant Viruses ◽  
Membrane Association ◽  
Leaf Blotch ◽  
Viral Movement Protein ◽  
Gene Block

Emaravirus is a recently described genus of negative-strand RNA plant viruses. Emaravirus P4 protein localizes to plasmodesmata, suggesting that it could be a viral movement protein (MP). In the current study, we showed that the P4 protein of raspberry leaf blotch emaravirus (RLBV) rescued the cell-to-cell movement of a defective potato virus X (PVX) that had a deletion mutation in the triple gene block 1 movement-associated protein. This demonstrated that RLBV P4 is a functional MP. Sequence analyses revealed that P4 is a distant member of the 30K superfamily of MPs. All MPs of this family contain two highly conserved regions predicted to form β-strands, namely β1 and β2. We explored by alanine mutagenesis the role of two residues of P4 (Ile106 and Asp127) located in each of these strands. We also made the equivalent substitutions in the 29K MP of tobacco rattle virus, another member of the 30K superfamily. All substitutions abolished the ability to complement PVX movement, except for the I106A substitution in the β1 region of P4. This region has been shown to mediate membrane association of 30K MPs; our results show that it is possible to make non-conservative substitutions of a well-conserved aliphatic residue within β1 without preventing the membrane association or movement function of P4.

scholarly journals Expression Strategy of the Potato Virus X Triple Gene Block

1991 ◽  
Vol 72 (8) ◽  
pp. 2039-2042 ◽  
Author(s):  
S. Yu. Morozov ◽  
N. A. Miroshnichenko ◽  
A. G. Solovyev ◽  
O. N. Fedorkin ◽  
D. A. Zelenina ◽  
...  
Keyword(s):  
Potato Virus ◽  
Triple Gene Block ◽  
Potato Virus X ◽  
Gene Block

scholarly journals Mutation of a chloroplast-targeting signal in Alternanthera mosaic virus TGB3 impairs cell-to-cell movement and eliminates long-distance virus movement

2010 ◽  
Vol 91 (8) ◽  
pp. 2102-2115 ◽  
Author(s):  
Hyoun-Sub Lim ◽  
Anna Maria Vaira ◽  
Hanhong Bae ◽  
Jennifer N. Bragg ◽  
Steven E. Ruzin ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Critical Role ◽  
Triple Gene Block ◽  
Cell Movement ◽  
Potato Virus X ◽  
Start Codon ◽  
Long Distance ◽  
Mesophyll Cells ◽  
Chloroplast Targeting ◽  
Gene Block

Cell-to-cell movement of potexviruses requires coordinated action of the coat protein and triple gene block (TGB) proteins. The structural properties of Alternanthera mosaic virus (AltMV) TGB3 were examined by methods differentiating between signal peptides and transmembrane domains, and its subcellular localization was studied by Agrobacterium-mediated transient expression and confocal microscopy. Unlike potato virus X (PVX) TGB3, AltMV TGB3 was not associated with the endoplasmic reticulum, and accumulated preferentially in mesophyll cells. Deletion and site-specific mutagenesis revealed an internal signal VL(17,18) of TGB3 essential for chloroplast localization, and either deletion of the TGB3 start codon or alteration of the chloroplast-localization signal limited cell-to-cell movement to the epidermis, yielding a virus that was unable to move into the mesophyll layer. Overexpression of AltMV TGB3 from either AltMV or PVX infectious clones resulted in veinal necrosis and vesiculation at the chloroplast membrane, a cytopathology not observed in wild-type infections. The distinctive mesophyll and chloroplast localization of AltMV TGB3 highlights the critical role played by mesophyll targeting in virus long-distance movement within plants.

scholarly journals In Vivo Translation of the Triple Gene Block of Potato Virus X Requires Two Subgenomic mRNAs

1998 ◽  
Vol 72 (10) ◽  
pp. 8316-8320 ◽  
Author(s):  
Jeanmarie Verchot ◽  
Susan M. Angell ◽  
David C. Baulcombe
Keyword(s):  
Potato Virus ◽  
Triple Gene Block ◽  
Mrna Translation ◽  
Potato Virus X ◽  
Open Reading Frames ◽  
Movement Proteins ◽  
Gene Block ◽  
Overlapping Open Reading Frames ◽  
Reading Frames

ABSTRACT The 25-kilodalton (25K), 12K, and 8K movement proteins of potato virus X are derived from overlapping open reading frames (ORFs). Using an in vivo complementation assay, we have shown that the 25K protein is expressed from a functionally monocistronic mRNA, whereas the 12K and 8K proteins are from a bicistronic mRNA. Translation of the 8K ORF is by leaky ribosome scanning through the 12K ORF.

scholarly journals Evidence that the Linker between the Methyltransferase and Helicase Domains of Potato Virus X Replicase Is Involved in Homologous RNA Recombination

2009 ◽  
Vol 83 (15) ◽  
pp. 7761-7769 ◽  
Author(s):  
Heidrun-Katharina Draghici ◽  
Mark Varrelmann
Keyword(s):  
Coat Protein ◽  
Potato Virus ◽  
Fluorescent Protein ◽  
Triple Gene Block ◽  
Leaf Tissue ◽  
Potato Virus X ◽  
Wild Type Virus ◽  
Rna Recombination ◽  
Gene Block

ABSTRACT Recombination in RNA viruses, one of the main factors contributing to their genetic variability and evolution, is a widespread phenomenon. In this study, an in vivo assay to characterize RNA recombination in potato virus X (PVX), under high selection pressure, was established. Agrobacterium tumefaciens was used to express in Nicotiana benthamiana leaf tissue both a PVX isolate labeled with green fluorescent protein (GFP) containing a coat protein deletion mutation (ΔCP) and a transcript encoding a functional coat protein +3′-ntr. Coexpression of the constructs led to virus movement and systemic infection; reconstituted recombinants were observed in 92% of inoculated plants. Similar results were obtained using particle bombardment, demonstrating that recombination mediated by A. tumefaciens was not responsible for the occurrence of PXC recombinants. The speed of recombination could be estimated by agroinfection of two PVX mutants lacking the 3′ and 5′ halves of the genome, respectively, with an overlap in the triple gene block 1 gene, allowing GFP expression only in the case of recombination. Ten different pentapeptide insertion scanning replicase mutants with replication abilities comparable to wild-type virus were applied in the different recombination assays. Two neighboring mutants affecting the linker between the methyltransferase and helicase domains were shown to be strongly debilitated in their ability to recombine. The possible functional separation of replication and recombination in the replicase molecule supports the model that RNA recombination represents a distinct function of this protein, although the underlying mechanism still needs to be investigated.

scholarly journals Tritium planigraphy study of structural alterations in the coat protein of Potato virus X induced by binding of its triple gene block 1 protein to virions

FEBS Journal ◽  
2009 ◽  
Vol 276 (23) ◽  
pp. 7006-7015 ◽  
Author(s):  
Elena Lukashina ◽  
Gennady Badun ◽  
Natalia Fedorova ◽  
Alexander Ksenofontov ◽  
Maria Nemykh ◽  
...  
Keyword(s):  
Coat Protein ◽  
Potato Virus ◽  
Triple Gene Block ◽  
Potato Virus X ◽  
Structural Alterations ◽  
Tritium Planigraphy ◽  
Gene Block
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