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Myosins VIII and XI play distinct roles in reproduction and transport of tobacco mosaic virus.

Amari K, Di Donato M, Dolja VV, Heinlein M - PLoS Pathog. (2014)

Bottom Line: The inactivation of myosin XI-2 but not of myosin XI-K affected the localization pattern of the 126k replicase subunit and the level of TMV accumulation.The inhibition of myosins VIII-1, VIII-2 and VIII-B abolished MP localization to PD and caused its retention at the plasma membrane.Thus, TMV appears to recruit distinct myosins for different steps in the cell-to-cell spread of the infection.

View Article: PubMed Central - PubMed

Affiliation: Zürich-Basel Plant Science Center, Botany, Department of Environmental Sciences, University of Basel, Basel, Switzerland.

ABSTRACT
Viruses are obligatory parasites that depend on host cellular factors for their replication as well as for their local and systemic movement to establish infection. Although myosin motors are thought to contribute to plant virus infection, their exact roles in the specific infection steps have not been addressed. Here we investigated the replication, cell-to-cell and systemic spread of Tobacco mosaic virus (TMV) using dominant negative inhibition of myosin activity. We found that interference with the functions of three class VIII myosins and two class XI myosins significantly reduced the local and long-distance transport of the virus. We further determined that the inactivation of myosins XI-2 and XI-K affected the structure and dynamic behavior of the ER leading to aggregation of the viral movement protein (MP) and to a delay in the MP accumulation in plasmodesmata (PD). The inactivation of myosin XI-2 but not of myosin XI-K affected the localization pattern of the 126k replicase subunit and the level of TMV accumulation. The inhibition of myosins VIII-1, VIII-2 and VIII-B abolished MP localization to PD and caused its retention at the plasma membrane. These results suggest that class XI myosins contribute to the viral propagation and intracellular trafficking, whereas myosins VIII are specifically required for the MP targeting to and virus movement through the PD. Thus, TMV appears to recruit distinct myosins for different steps in the cell-to-cell spread of the infection.

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Inactivation of myosin VIII causes patchy accumulation of MP at the PM.A to C, remorin:GFP and MP:RFP co-localize at the PM in the presence of myosin VIII-B tails. A, remorin:GFP; B, MP:RFP; C, merged images. D to F, surface view on the PM. Remorin:GFP and MP:RFP localize to different patches at the PM in the presence of myosin VIII-B tails. D, remorin:GFP; E, MP:RFP; F, merged images. G to I, in the absence of myosin VIII-B tails the MP:RFP accumulates in PD. G, remorin:GFP; H, MP:RFP; I, merged images. J to L, surface view of the PM. In the absence of myosin VIII-B tails, the MP:RFP does not accumulate in patchy pattern within the PM. J, remorin:GFP; K, MP:RFP; L, merged images. Proteins were expressed by co-agroinfiltration and observed at 1 dpa. Scale bars, 10 µm.
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ppat-1004448-g008: Inactivation of myosin VIII causes patchy accumulation of MP at the PM.A to C, remorin:GFP and MP:RFP co-localize at the PM in the presence of myosin VIII-B tails. A, remorin:GFP; B, MP:RFP; C, merged images. D to F, surface view on the PM. Remorin:GFP and MP:RFP localize to different patches at the PM in the presence of myosin VIII-B tails. D, remorin:GFP; E, MP:RFP; F, merged images. G to I, in the absence of myosin VIII-B tails the MP:RFP accumulates in PD. G, remorin:GFP; H, MP:RFP; I, merged images. J to L, surface view of the PM. In the absence of myosin VIII-B tails, the MP:RFP does not accumulate in patchy pattern within the PM. J, remorin:GFP; K, MP:RFP; L, merged images. Proteins were expressed by co-agroinfiltration and observed at 1 dpa. Scale bars, 10 µm.

Mentions: To further investigate the TMV MP redistribution upon co-expression with myosin VIII-B tails, we in addition co-expressed remorin:GFP, which is targeted to PD and to plasma membrane (PM) lipid rafts independently of myosins XI and VIII [5], [43]. In the presence of myosin VIII-B tails, the pattern of MP:RFP distribution was similar to that of remorin:GFP, indicating that inactivation of the myosin VIII-B results in the relocalization of MP along the PM (Figure 8A-C). In PM surface view, the MP:RFP appeared in small immobile patches similar to patches of remorin:GFP (Figure 8D-E). However, there was no substantial co-localization between these proteins suggesting that the MP localized to different subdomains within or in the vicinity of the PM (Figure 8F). Co-expression MP:RFP with remorin:GFP in the absence of myosin VIII-B tails had no effect on the localization of the MP to PD (Figure 8G-I). In PM surface view the MP:RFP also did not show any significant accumulation to patches in the membrane (Figure 8J-L). Thus, the localization of MP to PM patches is an effect of myosin VIII inhibition and not caused by remorin:GFP expression.


Myosins VIII and XI play distinct roles in reproduction and transport of tobacco mosaic virus.

Amari K, Di Donato M, Dolja VV, Heinlein M - PLoS Pathog. (2014)

Inactivation of myosin VIII causes patchy accumulation of MP at the PM.A to C, remorin:GFP and MP:RFP co-localize at the PM in the presence of myosin VIII-B tails. A, remorin:GFP; B, MP:RFP; C, merged images. D to F, surface view on the PM. Remorin:GFP and MP:RFP localize to different patches at the PM in the presence of myosin VIII-B tails. D, remorin:GFP; E, MP:RFP; F, merged images. G to I, in the absence of myosin VIII-B tails the MP:RFP accumulates in PD. G, remorin:GFP; H, MP:RFP; I, merged images. J to L, surface view of the PM. In the absence of myosin VIII-B tails, the MP:RFP does not accumulate in patchy pattern within the PM. J, remorin:GFP; K, MP:RFP; L, merged images. Proteins were expressed by co-agroinfiltration and observed at 1 dpa. Scale bars, 10 µm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4199776&req=5

ppat-1004448-g008: Inactivation of myosin VIII causes patchy accumulation of MP at the PM.A to C, remorin:GFP and MP:RFP co-localize at the PM in the presence of myosin VIII-B tails. A, remorin:GFP; B, MP:RFP; C, merged images. D to F, surface view on the PM. Remorin:GFP and MP:RFP localize to different patches at the PM in the presence of myosin VIII-B tails. D, remorin:GFP; E, MP:RFP; F, merged images. G to I, in the absence of myosin VIII-B tails the MP:RFP accumulates in PD. G, remorin:GFP; H, MP:RFP; I, merged images. J to L, surface view of the PM. In the absence of myosin VIII-B tails, the MP:RFP does not accumulate in patchy pattern within the PM. J, remorin:GFP; K, MP:RFP; L, merged images. Proteins were expressed by co-agroinfiltration and observed at 1 dpa. Scale bars, 10 µm.
Mentions: To further investigate the TMV MP redistribution upon co-expression with myosin VIII-B tails, we in addition co-expressed remorin:GFP, which is targeted to PD and to plasma membrane (PM) lipid rafts independently of myosins XI and VIII [5], [43]. In the presence of myosin VIII-B tails, the pattern of MP:RFP distribution was similar to that of remorin:GFP, indicating that inactivation of the myosin VIII-B results in the relocalization of MP along the PM (Figure 8A-C). In PM surface view, the MP:RFP appeared in small immobile patches similar to patches of remorin:GFP (Figure 8D-E). However, there was no substantial co-localization between these proteins suggesting that the MP localized to different subdomains within or in the vicinity of the PM (Figure 8F). Co-expression MP:RFP with remorin:GFP in the absence of myosin VIII-B tails had no effect on the localization of the MP to PD (Figure 8G-I). In PM surface view the MP:RFP also did not show any significant accumulation to patches in the membrane (Figure 8J-L). Thus, the localization of MP to PM patches is an effect of myosin VIII inhibition and not caused by remorin:GFP expression.

Bottom Line: The inactivation of myosin XI-2 but not of myosin XI-K affected the localization pattern of the 126k replicase subunit and the level of TMV accumulation.The inhibition of myosins VIII-1, VIII-2 and VIII-B abolished MP localization to PD and caused its retention at the plasma membrane.Thus, TMV appears to recruit distinct myosins for different steps in the cell-to-cell spread of the infection.

View Article: PubMed Central - PubMed

Affiliation: Zürich-Basel Plant Science Center, Botany, Department of Environmental Sciences, University of Basel, Basel, Switzerland.

ABSTRACT
Viruses are obligatory parasites that depend on host cellular factors for their replication as well as for their local and systemic movement to establish infection. Although myosin motors are thought to contribute to plant virus infection, their exact roles in the specific infection steps have not been addressed. Here we investigated the replication, cell-to-cell and systemic spread of Tobacco mosaic virus (TMV) using dominant negative inhibition of myosin activity. We found that interference with the functions of three class VIII myosins and two class XI myosins significantly reduced the local and long-distance transport of the virus. We further determined that the inactivation of myosins XI-2 and XI-K affected the structure and dynamic behavior of the ER leading to aggregation of the viral movement protein (MP) and to a delay in the MP accumulation in plasmodesmata (PD). The inactivation of myosin XI-2 but not of myosin XI-K affected the localization pattern of the 126k replicase subunit and the level of TMV accumulation. The inhibition of myosins VIII-1, VIII-2 and VIII-B abolished MP localization to PD and caused its retention at the plasma membrane. These results suggest that class XI myosins contribute to the viral propagation and intracellular trafficking, whereas myosins VIII are specifically required for the MP targeting to and virus movement through the PD. Thus, TMV appears to recruit distinct myosins for different steps in the cell-to-cell spread of the infection.

Show MeSH
Related in: MedlinePlus