Structure of Flexible Filamentous Plant Viruses

Department of Biological Sciences, Vanderbilt University, Box 351634, Station B, Nashville, TN 37235, USA.
Journal of Virology (Impact Factor: 4.44). 08/2008; 82(19):9546-54. DOI: 10.1128/JVI.00895-08
Source: PubMed


Flexible filamentous viruses make up a large fraction of the known plant viruses, but in comparison with those of other viruses,
very little is known about their structures. We have used fiber diffraction, cryo-electron microscopy, and scanning transmission
electron microscopy to determine the symmetry of a potyvirus, soybean mosaic virus; to confirm the symmetry of a potexvirus,
potato virus X; and to determine the low-resolution structures of both viruses. We conclude that these viruses and, by implication,
most or all flexible filamentous plant viruses share a common coat protein fold and helical symmetry, with slightly less than
9 subunits per helical turn.

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Available from: Esther Bullitt
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    • "Even for tobamoviruses, the X-ray fiber diffraction [2] and cryoelectron microscopy [3] data with a resolution of 3–5 Å are insufficient for elucidating the mechanisms of virus assembly in vitro and in vivo, especially since important differences between the results obtained by these two methods exist. For potyviruses, the best achievement in this field to date is 14 Å resolution fiber diffraction and cryoelectron microscopy data from Dr. Stubbs’s laboratory [4]. These data made it possible to estimate only overall dimensions of coat protein (CP) subunits in virions. "
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    ABSTRACT: Potyviruses represent the most biologically successful group of plant viruses, but to our knowledge, this work is the first detailed study of physicochemical characteristics of potyvirus virions. We measured the UV absorption, far and near UV circular dichroism spectra, intrinsic fluorescence spectra, and differential scanning calorimetry (DSC) melting curves of intact particles of a potato virus A (PVA). PVA virions proved to have a peculiar combination of physicochemical properties. The intravirus coat protein (CP) subunits were shown to contain an unusually high fraction of disordered structures, whereas PVA virions had an almost normal thermal stability. Upon heating from 20°C to 55°C, the fraction of disordered structures in the intravirus CP further increased, while PVA virions remained intact at up to 55°C, after which their disruption (and DSC melting) started. We suggest that the structure of PVA virions below 55°C is stabilized by interactions between the remaining structured segments of intravirus CP. It is not improbable that the biological efficiency of PVA relies on the disordered structure of intravirus CP.
    Full-text · Article · Jul 2013 · PLoS ONE
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    • "Finch (1965) pointed out that these spacings and the distribution of intensities on the off-meridional layer lines suggest that there are 5q+1 coat protein subunits in five turns of the viral helix, where q is an integer. Although the possibility of 5q−1 could not be completely excluded, the pair of layer lines 20 and 21 near the meridian (Fig. 2) supports 5q+1; the pair would be 19 and 20 if the number of subunits in the repeating unit were 5q−1 (Kendall et al., 2008). "
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    ABSTRACT: Barley stripe mosaic virus (BSMV) is the type member of the genus Hordeivirus, rigid, rod-shaped viruses in the family Virgaviridae. We have used fiber diffraction and cryo-electron microscopy to determine the helical symmetry of BSMV to be 23.2 subunits per turn of the viral helix, and to obtain a low-resolution model of the virus by helical reconstruction methods. Features in the model support a structural relationship between the coat proteins of the hordeiviruses and the tobamoviruses.
    Preview · Article · May 2013 · Virology
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    • "). PVX has filamentous particles consisting of c. 1260 coat protein subunits encapsidating a single RNA molecule. Although an atomic resolution structure of the coat protein subunits is not available, the overall architecture of the viral particles is known (Kendall et al., 2008 "
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    ABSTRACT: 1 I. 1 II. 3 III. 5 IV. 8 9 References 9 SUMMARY: This review discusses the varying roles that have been played by many plant-viral regulatory sequences and proteins in the creation of plant-based expression systems and virus particles for use in nanotechnology. Essentially, there are two ways of expressing an exogenous protein: the creation of transgenic plants possessing a stably integrated gene construction, or the transient expression of the desired gene following the infiltration of the gene construct. Both depend on disarmed strains of Agrobacterium tumefaciens to deliver the created gene construction into cell nuclei, usually through the deployment of virus-derived components. The importance of efficient mRNA translation in the latter process is highlighted. Plant viruses replicate to sustain an infection to promote their survival. The major product of this, the virus particle, is finding increasing roles in the emerging field of bionanotechnology. One of the major products of plant-viral expression is the virus-like particle (VLP). These are increasingly playing a role in vaccine development. Similarly, many VLPs are suitable for the investigation of the many facets of the emerging field of synthetic biology, which encompasses the design and construction of new biological functions and systems not found in nature. Genetic and chemical modifications to plant-generated VLPs serve as ideal starter templates for many downstream synthetic biology applications.
    Preview · Article · Mar 2013 · New Phytologist
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