Role of microtubules in the intracellular distribution of tobacco mosaic virus movement protein

Más, Paloma Díaz; Beachy, Roger N.

doi:10.1073/pnas.97.22.12345

Cited by 58 publications

(24 citation statements)

References 42 publications

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“…The frequently observed localization patterns of MP30 comprising accumulation at ER-associated punctae, microtubules, large bodies, and cell wallassociated punctae have been combined in a model for TMV cell-to-cell transport that involves transfer of MP30 and viral RNA from the ER via a microtubular delivery mechanism toward and through plasmodesmata (Lazarowitz and Beachy, 1999;Tzfira et al, 2000;Haywood et al, 2002;Heinlein, 2002), thereby indicating a movement promoting role of microtubules in transport of the MP30-vRNA complex (Heinlein et al, 1995McLean et al, 1995;Mas and Beachy, 2000;Boyko et al, 2000aBoyko et al, , 2000bKotlizky et al, 2001). On the other hand, microtubules have also been implicated in MP30 degradation (Padgett et al, 1996;Mas and Beachy, 1999;Reichel and Beachy, 2000).…”

Section: Discussionmentioning

confidence: 99%

“…There, MP30 induces an increase in plasmodesmal size exclusion limit and facilitates the transport of the vRNA-MP30 complex through the enlarged plasmodesmal channels into adjacent cells (Lazarowitz and Beachy, 1999;Tzfira et al, 2000;Haywood et al, 2002;Heinlein, 2002). In line with this model, microtubules have been functionally implicated in guiding vRNA-MP30 complexes toward plasmodesmata (Mas and Beachy, 2000; Boyko et al, 2000a Boyko et al, , 2000b. However, an alternate, non-movement-promoting role of microtubules in providing a route toward an MP30 degradation site was suggested (Padgett et al, 1996;Mas and Beachy, 1999;Reichel and Beachy, 2000).…”

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confidence: 97%

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MPB2C, a Microtubule-Associated Plant Protein Binds to and Interferes with Cell-to-Cell Transport of Tobacco Mosaic Virus Movement Protein

et al. 2003

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The movement protein of tobacco mosaic virus, MP30, mediates viral cell-to-cell transport via plasmodesmata. The complex MP30 intra-and intercellular distribution pattern includes localization to the endoplasmic reticulum, cytoplasmic bodies, microtubules, and plasmodesmata and likely requires interaction with plant endogenous factors. We have identified and analyzed an MP30-interacting protein, MPB2C, from the host plant Nicotiana tabacum. MPB2C constitutes a previously uncharacterized microtubule-associated protein that binds to and colocalizes with MP30 at microtubules. In vivo studies indicate that MPB2C mediates accumulation of MP30 at microtubules and interferes with MP30 cell-to-cell movement. In contrast, intercellular transport of a functionally enhanced MP30 mutant, which does not accumulate and colocalize with MP30 at microtubules, is not impaired by MPB2C. Together, these data support the concept that MPB2C is not required for MP30 cell-to-cell movement but may act as a negative effector of MP30 cell-to-cell transport activity.Plant viruses produce movement proteins required to mediate cell-to-cell spread of the viral genomic information via plasmodesmata (Lucas, 1995;Lazarowitz and Beachy, 1999;McLean and Zambryski, 2000;Tzfira et al., 2000;Haywood et al., 2002;Heinlein, 2002). Tobacco mosaic virus (TMV), a virus with a (ϩ) single-stranded RNA genome encodes one of the most extensively studied movement proteins, MP30. Several biochemical and cell biological features of MP30 were revealed: MP30 binds cooperatively single-stranded nucleic acids (Citovsky et al., 1990), interacts with the tubulin-and actin-based cytoskeleton (Heinlein et al., 1995;McLean et al., 1995), associates to the endoplasmic reticulum (ER; Heinlein et al., 1998;Reichel and Beachy, 1998;Mas and Beachy, 1999;Gillespie et al., 2002), and increases the size exclusion limit of plasmodesmata (Wolf et al., 1989;Waigmann et al., 1994). In the current model, MP30 is proposed to form complexes with genomic TMV-RNA (vRNA) and to move these vRNA-protein complexes from ER-associated sites of synthesis throughout the cell via the cytoskeletal network toward plasmodesmata. There, MP30 induces an increase in plasmodesmal size exclusion limit and facilitates the transport of the vRNA-MP30 complex through the enlarged plasmodesmal channels into adjacent cells (Lazarowitz and Beachy, 1999;Tzfira et al., 2000;Haywood et al., 2002;Heinlein, 2002). In line with this model, microtubules have been functionally implicated in guiding vRNA-MP30 complexes toward plasmodesmata (Mas and Beachy, 2000; Boyko et al., 2000a Boyko et al., , 2000b. However, an alternate, non-movement-promoting role of microtubules in providing a route toward an MP30 degradation site was suggested (Padgett et al., 1996;Mas and Beachy, 1999;Reichel and Beachy, 2000). This model is supported by the observation that TMV was able to spread in tissues with functionally impaired microtubules and by studies performed with a mutant variant of MP30, MP R3 with strongly decreased affinity...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 97%

MPB2C, a Microtubule-Associated Plant Protein Binds to and Interferes with Cell-to-Cell Transport of Tobacco Mosaic Virus Movement Protein

et al. 2003

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“…SV40 infection was similarly inhibited, in agreement with previous findings. Microtubules have been shown to be required for infection by several other viruses (33,48,57). In the case of SV40, it is thought that microtubules transport SV40 in caveolin-free vesicles from the caveosome to the smooth endoplasmic reticulum.…”

Section: Discussionmentioning

confidence: 99%

Contrasting Roles of Endosomal pH and the Cytoskeleton in Infection of Human Glial Cells by JC Virus and Simian Virus 40

Ashok¹,

Atwood

2003

J Virol

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Infection of eukaryotic cells by pathogens requires the efficient use of host cell endocytic and cytoplasmic transport mechanisms. Understanding how these cellular functions are exploited by microorganisms allows us to better define the basic biology of pathogenesis while providing better insight into normal cellular functions. In this report we compare and contrast intracellular transport and trafficking of the human polyomavirus JC virus (JCV) with that of simian virus 40 (SV40). We have previously shown that infection of human glial cells by JCV requires clathrin-dependent endocytosis. In contrast, infection of cells by SV40 proceeds by caveoladependent endocytosis. We now examine the roles of endosomal pH and the cellular cytoskeleton during infection of glial cells by both viruses. Our results demonstrate that JCV infection is sensitive to disruption of endosomal pH, whereas SV40 infection is pH independent. Infection by JCV is inhibited by treatment of glial cells with cytochalasin D, nocodazole, and acrylamide, whereas SV40 infection is affected only by nocodazole. These data point to critical differences between JCV and SV40 in terms of endocytosis and intracellular trafficking of their DNA genomes to the nucleus. These data also suggest a unique sequential involvement of cytoskeletal elements during infection of glial cells by JCV.

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“…Intracellular localization of mutant MPs. It has been reported that the MP of tobamoviruses is associated with plasmodesmata, the cytoskeleton, microtubules, and the endoplasmic reticulum (2,11,13,17,19,25). This intracellular localization is believed to be closely associated with MP function.…”

Section: Stability Of Mutant Mps In Vivomentioning

confidence: 94%

Defective Tobamovirus Movement Protein Lacking Wild-Type Phosphorylation Sites Can Be Complemented by Substitutions Found in Revertants

Kawakami

Hori

Hosokawa

et al. 2003

J Virol

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We reported previously that the movement protein (MP) of tomato mosaic tobamovirus is phosphorylated, and we proposed that MP phosphorylation is important for viral pathogenesis. Experimental data indicated that phosphorylation enhances the stability of MP in vivo and enables the protein to assume the correct intracellular location to perform its function. A mutant virus designated 37A238A was constructed; this virus lacked two serine residues within the MP, which prevented its phosphorylation. In the present study, we inoculated plants with the 37A238A mutant, and as expected, it was unable to produce local lesions on the leaves. However, after an extended period, we found that lesions did occur, which were due to revertant viruses. Several revertants were isolated, and the genetic changes in their MPs were examined together with any changes in their in vivo characteristics. We found that reversion to virulence was associated first with increased MP stability in infected cells and second with a shift in MP intracellular localization over time. In one case, the revertant MP was not phosphorylated in vivo, but it was functional.After an initial round of replication in primary infected cells, plant viruses spread to adjacent tissues via the plasmodesmata, thus establishing systemic infection (4,6,7,16,21,26). In tobamoviruses (ToMV) the 30-kDa movement protein (MP) is essential for efficient intercellular transport (8,22). Plant viruses lacking a functional MP cannot move from the primary infected cell (4,7,16,21,22). Despite its importance for viral pathogenesis, the molecular mechanism by which MP enables intercellular transport of ToMV in plants is unknown. Recently it was shown that the replicase-coding region is also involved in cell-to-cell movement by an as-yet-unknown mechanism (12).In previous studies, we found that MP is produced transiently during the infection cycle (30) and is phosphorylated posttranslationally in infected cells (32). We have also reported that recombinant MP expressed in Escherichia coli can be phosphorylated within the C-terminal portion of the protein by casein kinase II (18). Citovsky et al. (5) and Waigmann et al. (29) also reported in vitro kinase activities that phosphorylate the C-terminal portion of MP and discussed its relevance to function.We analyzed the phosphorylation sites in vivo by using MP mutants that were already available and additional artificially constructed alanine-scanned mutants (13). We isolated 32 Plabeled MP tryptic peptides from protoplasts infected with the different mutants, compared the tryptic maps with that of wildtype MP, and thus narrowed down the candidate phosphorylation sites. The phosphorylation site identified first was serine 238. The serine residue was replaced with alanine to make a new mutant designated LQ238A. However, the MP produced by this mutant was still phosphorylated and functional.We assumed that the serine residue or residues targeted for phosphorylation are likely to be more conserved than other residues. The sequences of sev...

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Role of microtubules in the intracellular distribution of tobacco mosaic virus movement protein

Abstract: Despite its central role in virus infection

Cited by 58 publications

References 42 publications

MPB2C, a Microtubule-Associated Plant Protein Binds to and Interferes with Cell-to-Cell Transport of Tobacco Mosaic Virus Movement Protein

MPB2C, a Microtubule-Associated Plant Protein Binds to and Interferes with Cell-to-Cell Transport of Tobacco Mosaic Virus Movement Protein

Contrasting Roles of Endosomal pH and the Cytoskeleton in Infection of Human Glial Cells by JC Virus and Simian Virus 40

Defective Tobamovirus Movement Protein Lacking Wild-Type Phosphorylation Sites Can Be Complemented by Substitutions Found in Revertants

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