Transport of TMV Movement Protein Particles Associated with the Targeting of RNA to Plasmodesmata

Abstract

The cell-to-cell movement of Tobacco mosaic virus through plasmodesmata (PD) requires virus-encoded movement protein (MP). The MP targets PD through the endoplasmic reticulum (ER)/actin network, whereas the intercellular movement of the viral RNA genome has been correlated with the association of the MP with mobile, microtubule-proximal particles in cells at the leading front of infection as well as the accumulation of the protein on the microtubule network during later infection stages. To understand how the associations of MP with ER and microtubules are functionally connected, we applied multiple marker three-dimensional confocal and time-lapse video microscopies to Nicotiana benthamiana cells expressing fluorescent MP, fluorescent RNA and fluorescent cellular markers. We report the reconstitution of MP-dependent RNA transport to PD in a transient assay. We show that transiently expressed MP occurs in association with small particles as observed during infection. The same MP accumulates in PD and mediates the transport of its messenger RNA transcript to the pore. In the cellular cortex, the particles occur at microtubuleproximal sites and can undergo ER-associated and latrunculin-sensitive movements between such sites. These and other observations suggest that the microtubule network performs anchorage and release functions for controlling the assembly and intracellular movement of MP-containing RNA transport particles in association with the ER.

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

“…Since MP traffics in the ER membrane (Brill et al, 2000;Wright et al, 2007;GuenouneGelbart et al, 2008;Sambade et al, 2008), this finding is in agreement with the reported ability of ER membrane proteins to continue their trafficking in the membrane upon disruption of actin filaments with LatB (Runions et al, 2006). Nevertheless, although an effect of LatB treatment on the spread of infection was not observed, the absence of intact actin filaments has important effects with respect to the efficiency of PD targeting.…”

“…The inhibition of Golgi trafficking upon transient ABD2:GFP expression may thus reflect inhibition of the trafficking of protein complexes in the ER membrane. Given that TMV movement occurs via diffusion in the ER membrane (Brill et al, 2000;Wright et al, 2007;Guenoune-Gelbart et al, 2008;Sambade et al, 2008), we propose that the ABD2:GFP-mediated restriction in TMV movement occurs through obstruction of the ER membrane by immobilized protein complexes (Fig. 7).…”

“…Nevertheless, inhibition of TMV movement following prolonged LatB treatment may be expected, since the absence of an intact actin network gradually induces the contraction of the ER (Wright et al, 2007). The contraction of the ER is not observed if the drug is applied during shorter time periods (Boevink et al, 1998;Sambade et al, 2008). Thus, the general structure and function of the ER is independent of actin and persists over a certain time in the presence of LatB.…”

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

“…During the course of infection, as well as when ectopically expressed, the MP associates with PD, the ER/actin network, and microtubules (Heinlein et al, 1995Reichel and Beachy, 1998;Wright et al, 2007;Sambade et al, 2008;Hofmann et al, 2009;Boutant et al, 2010;Peña and Heinlein, 2012;Supplemental Fig. S1).…”

Análisis Funcional De Proteínas Codificadas Por El Virus De La Rotura Del Color De La Flor Del Pelargonium

“…Este proceso parece requerir la interacción de la MP con elementos del citoesqueleto intacto o con componentes individuales de los MT o los MF [Ashby et al, 2006;Wright et al, 2007;Sambade et al, 2008;Hofmann et al, 2009]. En este sentido, se ha especulado que los motivos homólogos a la tubulina vegetal presentes en p30 ( Fig.…”