Tubules of plant reoviruses exploit tropomodulin to regulate actin-based tubule motility in insect vector

Abstract

Plant reoviruses are known to exploit virion-packaging tubules formed by virus-encoding non-structural proteins for viral spread in insect vectors. Tubules are propelled by actin-based tubule motility (ABTM) to overcome membrane or tissue barriers in insect vectors. To further understand which insect factors mediate ABTM, we utilized yeast two-hybrid and bimolecular fluorescence complementation assays to test interactions between tubule protein Pns10 of rice dwarf virus (RDV), a plant reovirus, and proteins of its insect vector, the leafhopper Nephotettix cincticeps. Tropomodulin (Tmod), vitellogenin, and lipophorin precursor of N. cincticep displayed positive and strong interaction with Pns10, and actin-associated protein Tmod interacted with Pns10 in pull-down assay and the co-immunoprecipitation system. Further, we determined Pns10 tubules associated with Tmod in cultured cells and midgut of N. cincticep. The expression dynamic of Tmod was consistent with that of Pns10 and the fluctuation of RDV accumulation. Knockdown of Tmod inhibited the Pns10 expression and viral accumulation, thus decreasing the viruliferous rates of leafhopper. These results suggested that Tmod was involved in viral spread by directly interacting with Pns10 tubules, finally promoting RDV infection. This study provided direct evidence of plant reoviruses utilizing an actin-associated protein to manipulate ABTM in insect vectors, thus facilitating viral spread.

Gelsolin of insect vectors negatively regulates actin-based tubule motility of plant reoviruses

“…The investigation on the regulators of ABTM is beneficial for the improved understanding of the mechanism of ABTM. Our previous study revealed that Tmod, a positive regulator of RDV ABTM, functioned in viral infection by directly interacting with tubule protein Pns10 (Chen et al 2017). Because Tmod could control the length and stability of the actin-tropomyosin filament, Pns10 utilizes Tmod to elongate the Pns10 tubules to accomplish ABTM (Chen et al 2017).…”

“…During the process of ABTM, actin-associated proteins, including myosin, profilin, and cofilin, also positively participate in tubule formation or actin engine regulation (Wei et al 2008;Liu et al 2011;Chen et al 2012;Jia et al 2014;Mar et al 2014). In our previous publication, we showed that tropomodulin (Tmod), an actin-associated protein controlling the length and dynamics of the actin-tropomyosin filament, positively regulates RDV Pns10 tubule trafficking via the direct interaction with Pns10 (Chen et al 2017). This interaction promotes viral infection (Chen et al 2017).…”

“…In our previous publication, we showed that tropomodulin (Tmod), an actin-associated protein controlling the length and dynamics of the actin-tropomyosin filament, positively regulates RDV Pns10 tubule trafficking via the direct interaction with Pns10 (Chen et al 2017). This interaction promotes viral infection (Chen et al 2017). It is believed that the successful operation of ABTM for persistent viral infection is due to the evolutionary arms race and balance between positive and negative regulators.…”

RNA interference‐mediated knockdown and virus‐induced suppression of Troponin C gene adversely affect the behavior or fitness of the green rice leafhopper, Nephotettix cincticeps

“…Many intracellular pathogens, including viruses, parasites, and bacteria, invade, traffic within, and exit their target cells in a cytoskeleton‐dependent manner (Greber & Way, ; Gruenheid & Finlay, ). Recently, a model of actin‐based tubule motility for the spread of rice virus including RDV in insect vector has been proposed (Chen et al., ; Jia et al., ; Liao et al., ; Mao et al., ; Wei & Li, ). In this model, a direct interaction of tubule composed of RDV Pns10 , RGDV Pns11 , or SRBSDV P7‐1 protein with cellular skeleton components (actin, myosin, profilin, gelsolin, cofilin, and tropomodulin) was observed; these components formed a “lighted rocket” to propel the tubule to break through the membrane or tissue barriers for spread and transmission in insect vectors.…”

“…Glutathione S‐transferase (GST) pull‐down assay was conducted as Chen's and Liao's method (Chen, Wang, Ren, Xie, & Wei, ; Chen, Zhang, Zhang, Mao, & Wei, ; Liao et al., ). In brief, RDV Pns10 and Nc‐TnC genes were cloned into pGEX‐3X and pDEST‐17 to construct plasmids expressing GST and 6 × His fusion protein, respectively, with the primers of Pns103 ‐F/R and TnC5 ‐F/R (Table ).…”