Potato virus X: structure, disassembly and reconstitution

Abstract

SUMMARY This paper summarizes some structural characteristics of Potato virus X (PVX), the flexuous filamentous plant potexvirus. A model of PVX coat protein (CP) tertiary structure in the virion proposed on the basis of tritium planigraphy combined with predictions of the protein tertiary structure is described. A possible role of glycosylation and phosphorylation in the CP structure and function is discussed. Two forms of PVX virion disassembly are discussed: (i) the virion co-translational disassembly after PVX CP in situ phosphorylation and (ii) disassembly of PVX triggered by different factors after linear destabilization of the virion by binding of the PVX-coded movement protein (TGBp1) to one end of the polar CP-helix. Special emphasis was placed on a translational activation of encapsidated PVX RNA and rapid disassembly of TGBp1-PVX complexes into free RNA and CP. The results of experiments on the PVX CP repolymerization and PVX reconstitution are considered. In particular, the products assembled from PVX RNA, CP and TGBp1 were examined. Single-tailed particles were found with a helical, head-like structure consisting of helically arranged CP subunits located at the 5'-tail of RNA; the TGBp1 was bound to the end of the head. Translatable 'RNA-CP-TGBp1' complexes may represent the transport form of the PVX infection.

Thermal conversion of filamentous potato virus X into spherical particles with different properties from virions

“…A single linear positive-sense RNA molecule represents about 6% by weight of the virion [12]. PVX is a classic member of the flexible helical viruses group, while TMV is a classic member of the helical rod viruses group.…”

Unusual Features of Pomoviral RNA Movement

“…Therefore, the results are compatible with long-distance movement of virions that contain CP-RT and TGB1 at the tip. In this aspect, PMTV particles differ from those potato virus X (another TGB containing virus) where TGB1 is associated with one extremity but this interaction is thought to promote particle instability and RNA translation (Karpova et al, 2006; Atabekov et al, 2007). The role in virus movement of supplementary proteins incorporated at the tip of filamentous virus particles was first shown for beet yellows closterovirus (Peremyslov et al, 2004) and has also been suggested for potato potyviruses (Torrance et al, 2006).…”

Unraveling the Structure of Viral Replication Complexes at Super-Resolution

“…It serves as a model virus for analysis of RNA silencing and virus movement, as a vector for protein overexpression and knockdown and as a virus-induced gene silencing model (Batten et al, 2003; Verchot-Lubicz et al, 2007). The mechanically transmitted PVX virions are flexuous filaments with a length of about 470–580 nm and are composed of the 6.4 kb vRNA and ∼1300 subunits of coat protein (CP; Atabekov et al, 2007). …”