The N-Terminal Domain of PMTV TGB1 Movement Protein Is Required for Nucleolar Localization, Microtubule Association, and Long-Distance Movement

Abstract

The triple-gene-block (TGB)1 protein of Potato mop-top virus (PMTV) was fused to fluorescent proteins and expressed in epidermal cells of Nicotiana benthamiana under the control of the 35S promoter. TGB1 fluorescence was observed in the cytoplasm, nucleus, and nucleolus and occasionally associated with microtubules. When expressed from a modified virus (PMTV.YFP-TGB1) which formed local lesions but was not competent for systemic movement, yellow fluorescent protein (YFP)-TGB1 labeled plasmodesmata in cells at the leading edge of the lesion and plasmodesmata, microtubules, nuclei, and nucleoli in cells immediately behind the leading edge. Deletion of 84 amino acids from the N-terminus of unlabeled TGB1 within the PMTV genome abolished movement of viral RNA to noninoculated leaves. When the same deletion was introduced into PMTV.YFP-TGB1, labeling of microtubules and nucleoli was abolished. The N-terminal 84 amino acids of TGB1 were fused to green fluorescent protein (GFP) and expressed in epidermal cells where GFP localized strongly to the nucleolus (not seen with unfused GFP), indicating that these amino acids contain a nucleolar localization signal; the fusion protein did not label microtubules. This is the first report of nucleolar and microtubule association of a TGB movement protein. The results suggest that PMTV TGB1 requires interaction with nuclear components and, possibly, microtubules for long-distance movement of viral RNA.

Importin-α-Mediated Nucleolar Localization of Potato Mop-Top Virus TRIPLE GENE BLOCK1 (TGB1) Protein Facilitates Virus Systemic Movement, Whereas TGB1 Self-Interaction Is Required for Cell-to-Cell Movement in Nicotiana benthamiana

“…Later in infection, fluorescently labeled TGB1 is seen in the nucleus and accumulates in the nucleolus. Nucleolar TGB1 association has been shown to be necessary for longdistance movement (Wright et al, 2010).…”

Genetic dissection of a putative nucleolar localization signal in the coat protein of ourmia melon virus

“…Our results show that only a single nucleolar localization motif is present in OuMV CP. Only a few cases of plant viral proteins targeted to the nucleolus have been reported, and the NoLSs that have been characterized so far are rich in positively charged amino acids [2,7,8,11,19,20,[23][24][25][26]. Alfalfa mosaic virus (AMV), for instance, has a short NoLS that is rich in lysine and arginine residues at the N-terminus of the CP, which, in addition to its role as a sorting signal, acts as modulator of RNA binding and it is responsible for cell-to-cell and longdistance movement of AMV [8].…”

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

“…11). La mayoría de estas proteínas poseen dos segmentos TM que median la inserción en RE exponiendo los extremos N-t y C-t al lumen [Morosov & Solovyev, 2003;Schepetilnikov et al, 2005], aunque hay ejemplos en los cuales la topología de inserción parece ser justamente la opuesta [Tilsner et al, 2010].…”

“…Esta MP reorganiza los Cuerpos de Cajal y emplea las rutas de tráfico que involucran a estas estructuras para acceder al nucléolo, un paso que resulta esencial para la formación de partículas RNP competentes y para el movimiento sistémico del patógeno [Kim et al, 2007b]. Recientemente se ha demostrado que también la proteína TGBp1 de un pomovirus, el virus mop-top de la patata (Potato mop-top virus, PMTV), puede localizarse en núcleo y nucléolo, y se ha sugerido que este producto podría interaccionar con algún componente del núcleo y posiblemente con los MT [Wright et al, 2010].…”

“…También se ha observado en el citoplasma la TGBp1 de algunos hordeivirus y potexvirus, aunque en estos casos no formando parte de cuerpos de inclusión [Yang et al, 2000;Zamyatnin et al, 2004;Wright et al, 2010]. Igualmente, se ha descrito que alguna de las MP del DGB del género Carmovirus pueden localizarse en el citoplasma [Cohen et al, 2000b;García-Castillo et al, 2003].…”