Cell‐to‐cell movement of TMV RNA is temperature‐dependent and corresponds to the association of movement protein with microtubules

Abstract

SummaryThe movement protein (MP) of tobacco mosaic virus (TMV) is essential for spread of the viral RNA genome from cell to cell. During infection, the MP associates with microtubules, and it has been proposed that the cytoskeleton transports the viral ribonucleoprotein complex from ER sites of synthesis to plasmodesmata through which infection spreads into adjacent cells. However, microtubule association of MP was observed in cells undergoing late infection rather than in cells undergoing early infection at the leading edge of expanding infection sites where virus RNA cell-to-cell spread occurs. Therefore, alternative roles for microtubules in virus infection have been proposed, including a role in MP degradation. To further investigate the role of microtubules in virus pathogenesis, we tested the ef®ciency of cell-to-cell spread of infection and microtubule association of the MP in response to changes in temperature. We show that the subcellular distribution of MP is temperature-dependent and that a higher ef®ciency of intercellular transport of virus RNA at elevated temperatures corresponds to an increased association of MP with microtubules early in infection.

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

“…Second, treatment with oryzalin, a plant MT-depolymerizing agent, prevented the dispersion of vRNA to the periphery of the cell (12) and the replication bodies coalesced to form larger bodies (10). Third, a recent study suggests that the increased efficiency of intercellular movement of TMV RNA at elevated temperatures is correlated with an increased association of MP with MTs (30).…”

Inhibition of Tobacco Mosaic Virus Movement by Expression of an Actin-Binding Protein

“…We cannot exclude the possibility that ABD2:GFP binding to actin filaments interferes with MP:RFP binding. However, since other studies have demonstrated that the filaments to which MP binds in plant and mammalian cells are microtubules (Heinlein et al, 1995(Heinlein et al, , 1998Boyko et al, 2000aBoyko et al, , 2000bAshby et al, 2006;Ferralli et al, 2006), this possibility appears unlikely. Our observation is consistent with the finding that MP does not bind to actin filaments in mammalian cells (Ferralli et al, 2006), and actin is highly conserved between plants and mammals.…”

“…S1) and include the association with microtubules (Heinlein et al, 1998;Boyko et al, 2000b;Ashby et al, 2006). Because immunostaining procedures applied to fixed protoplasts have indicated that MP may also have the capacity to align along phalloidin-rhodamine-labeled microfilaments (McLean et al, 1995), we investigated whether some of the in vivo MP:RFP-decorated filaments may represent actin filaments.…”

Control of Tobacco mosaic virus Movement Protein Fate by CELL-DIVISION-CYCLE Protein48

“…Following accumulation of MP in virus factories, the infected cells accumulate the MP also along microtubules . The accumulation of MP in virus factories and on microtubules in cells behind the leading front of infection is dispensable for virus movement Boyko et al, 2000a). At these late infection stages, the virus factories may enable the virus to produce high virion titers (Laliberté and Sanfaçon, 2010;Tilsner et al, 2012), and the subsequent accumulation along microtubules may play a role in withdrawing MP from the cell-to-cell communication pathway and in stockpiling MP prior to degradation (Padgett et al, 1996;Gillespie et al, 2002).…”