Cell-to-cell movement of potato virus X involves distinct functions of the coat protein

Abstract

CP gene, was studied by transient co-expression with heterologous proteins. These data demonstrated that the potyvirus CPs and both the major and minor CPs of beet yellows closterovirus could complement cell-to-cell movement of PVX.CP-Xho but not PVX.∆CP. These data also indicated that the C-terminally truncated PVX CP lacked a movement function which could be provided in trans by the CPs of other filamentous viruses, whereas another movement determinant specified by some region outside the most C-terminal part of the PVX CP could not be complemented either by potyvirus or closterovirus CPs. Surprisingly, the CP of spherical cocksfoot mottle sobemovirus rescued all of the PVX CP movement functions, complementing the spread of PVX.CP-Xho and, to a lesser extent, PVX.∆CP. Both these mutants were also rescued by the tobacco mosaic virus (TMV) movement protein (MP). To shed light on the movement function of PVX CP, attempts were made to complement PVX.CP-Xho by a series of TMV MP mutants. An internal deletion abolished complementation, suggesting that the internal region of TMV MP, which includes a number of overlapping functional domains important for cell-to-cell transport, provides an activity complementing movement determinant(s) specified by the C-terminal region of PVX CP.

Helical capsids of plant viruses: architecture with structural lability

“…In addition to converting virions into a translatable form, TGB1 binding can be pertinent to virus transport in plants, since TGB1 can be directed to plasmodesmata by the TGB2 and TGB3 proteins (discussed in Morozov & Solovyev, 2003;Solovyev et al, 2012;Verchot-Lubicz et al, 2010). This plausible hypothesis is consistent with the observations that deletions in the potexvirus CP C-terminal region involved in interactions with the TGB1 protein, while having little effect on virion formation (see above), block virus cell-to-cell movement (Fedorkin et al, 2001;Forster et al, 1992). According to the current view, attachment of TGB1 molecules to virions serves for segregation of a progeny virion sub-population, which is both destined for cell-to-cell transport and capable, due to structural destabilization upon interaction with TGB1, of co-translational uncoating (discussed above) after translocation to a new cell (Atabekov et al, 2001).…”

“…This difference is suggested to determine the appearance of RNA-protein complexes, either filamentous virions or loose helical RNPs (Agirrezabala et al, 2015). However, the CP of a potexvirus PVX, lacking 18 C-terminal amino acid residues, is known to form virions similar in their appearance to the wild-type PVX virions both in vitro and in vivo (Fedorkin et al, 2001;Zayakina et al, 2008). Similarly, virus-like particles are detected in protoplasts infected with the potexvirus White clover mosaic virus encoding the CP C-terminally truncated by 31 amino acid residues (Forster et al, 1992).…”

A cis Element within Flowering Locus T mRNA Determines Its Mobility and Facilitates Trafficking of Heterologous Viral RNA

“…Deletion of viral CP prevented PVX/GFP⌬CP movement and restricted viral RNAs to single N. benthamiana epidermal cells. Thus, unlike the wild-type virus, PVX/GFP⌬CP was incapable of accessing the phloem to move systemically (10). It should be noted that free GFP, once loaded from the mesophyll into the sieve tube, can move over long distances in the phloem (16,17,31,32).…”

Nucleocytoplasmic Distribution Is Required for Activation of Resistance by the Potato NB-LRR Receptor Rx1 and Is Balanced by Its Functional Domains

“…Thus, the CP localization by itself does not exclude the nucleus as the compartment where recognition could take place. It is tempting to speculate that the roles the CP fulfills in PVX replication and cell-cell movement of viral RNA Fedorkin et al, 2001;Karpova et al, 2006;Bamunusinghe et al, 2009), which have been associated with the endomembrane system and plasmodesmata, form the ground for its recognition in the cytoplasm.…”