Polymorphism in the assembly of polyomavirus capsid protein VP1

Salunke, Dinakar M.; Caspar, D. L. D.; Garcea, Robert L.

doi:10.1016/s0006-3495(89)82735-3

Cited by 202 publications

(237 citation statements)

References 33 publications

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“…The pleomorphic nature of the interactions between the dimers of dimers that modulate the size of the final mHBsAg particle presumably underlie also the switch to icosahedral assembly that is required to form the complete HBV particles. This mechanism appears to be an extension of the conformational switching mechanism recognized as the cornerstone to the assembly of many icosahedral virus particles (15,(30)(31)(32). Finally, the antigenic properties of these particles, many millions of doses of which are administered every year as a recombinant HB vaccine, confirm that the presentation of surface epitopes on the octahedral structures mimics that in the intact virus.…”

Section: Resultsmentioning

confidence: 69%

“…Polyomavirus shows a level of pleomorphism similar to that of HBV: both form tubular structures as well as octahedral and icosahedral assemblies (33). Polyomavirus VP1 is able to assemble into these different structures as a result of changes in the way the pentamers link together, rather than changes in the basic building block of the assemblies (32,33). The SHBsAg dimers seem to echo this principle.…”

Section: Resultsmentioning

confidence: 98%

“…One other subviral octahedral assembly was described in ref. 32, that Schematic representation of possible T ϭ 3 and T ϭ 4 models for the Dane particle surface based on the assembly of sAg molecules observed for the small and large sAg particles. The T ϭ 3 core is coated by a T ϭ 3 surface where the twofold block (shown in broken line) binds across two HBcAg spikes (shown as circles) and is arranged in a manner similar to that found in the large sAg particle.…”

Section: Resultsmentioning

confidence: 99%

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Hepatitis B small surface antigen particles are octahedral

Gilbert

Beales

Blond

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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The infectious component of hepatitis B (HB) virus (HBV), the Dane particle, has a diameter of Ϸ44 nm and consists of a double-layered capsid particle enclosing a circular, incomplete double-stranded DNA genome. The outer capsid layer is formed from the HB surface antigen (HBsAg) and lipid, whereas the inner layer is formed from the HB core Ag assembled into an icosahedral structure. During chronic infection HBsAg is expressed in large excess as noninfectious quasispherical particles and tubules with Ϸ22-nm diameter. Here, we report cryo-EM reconstructions of spherical HBsAg particles at Ϸ12-Å resolution. We show that the particles possess different diameters and have separated them into two predominant populations, both of which have octahedral symmetry. Despite their differing diameters, the two forms of the particle have the same mass and are built through conformational switching of the same building block, a dimer of HBsAg. We propose that this conformational switching, combined with interactions with the underlying core, leads to the formation of HBV Dane particles of different sizes, dictated by the symmetry of the icosahedral core.cryo-EM ͉ subviral particle ͉ virus structure H epatitis B (HB) virus (HBV) is a major cause of both acute and chronic liver disease. It is estimated that there are Ϸ350 million carriers of the virus, and a high proportion of these will develop serious liver diseases, including hepatocellular carcinoma. The double-layered mature infectious particle, known as the Dane particle, is an icosahedral structure comprising an inner core formed from 180 or 240 copies of the HB core antigen (HBcAg) arranged with triangulation (T) numbers 3 or 4 and an outer proteolipid HB surface Ag (HBsAg) layer. The HBsAg envelope glycoprotein of HBV occurs in three forms, denoted by L (large), M (medium) and S (small), which form a nested set of products sharing a common C-terminal domain, the SHBsAg polypeptide. The SHBsAg itself has a molecular mass of Ϸ24 kDa and is predicted to be intimately associated with lipid, having four or five membrane-spanning helices, and is found in two forms, glycosylated and unglycosylated, in approximately equal amounts. SHBsAg glycosylation is a single biantennary glycan at Asn-146 and raises its molecular mass to Ϸ27 kDa (1, 2). About 80% of HBsAg is in the S form, which assembles with M and L forms into both the outer surface of the Dane particle and smaller subviral particles. These HBsAg subviral particles, known as 22-nm particles because of their diameter, are stabilized by disulfide bonds (3).HBsAg particles greatly outnumber mature virus particles and presumably act as decoys for the immune system. Although the 22-nm particles are predominately SHBsAg, tubular assemblies, also observed in the serum of chronic carriers, tend to be richer in LHBsAg. Because HBV subviral particles share important immunological determinants with mature virus, they can be used as effective immunogens. Indeed, expression of SHBsAg particles in yeast in the 1980s led to the developm...

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Section: Resultsmentioning

confidence: 69%

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Hepatitis B small surface antigen particles are octahedral

Gilbert

Beales

Blond

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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“…It has been demonstrated that bacterially expressed recombinant VP1 can self-assemble into capsid-like particles in vitro in the presence of calcium ions (Haynes et al, 1993 ;Salunke et al, 1986Salunke et al, , 1989 and that eukaryotic baculovirus-expressed polyomavirus VP1 can also produce capsid-like particles in the nuclei of insect cells (Delos et al, 1993 ;Forstova! et al, 1993 ;Li et al, 1995 ;Montross et al, 1991).…”

Section: Discussionmentioning

confidence: 99%

Use of the baculovirus system to assemble polyomavirus capsid-like particles with different polyomavirus structural proteins: analysis of the recombinant assembled capsid-like particles.

Gillock

Sweat

et al. 1999

Journal of General Virology

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The genes encoding the structural proteins (VP1, VP2 and VP3) of murine polyomavirus were cloned into the p2Bac dual multiple cloning site vector, individually or jointly, and the corresponding proteins were expressed in Spodoptera frugiperda (Sf9) insect cells by cotransfecting Sf9 cells with the constructed vector and the linear DNA of Autographa californica multiple nuclear polyhedrosis virus (AcMNPV). Recombinant capsid-like particles could be purified 5 days post-infection from Sf9 cells infected with AcMNPV-VP1, with or without the involvement of minor protein (VP2 or VP3). Although VP2 and VP3 alone could not generate recombinant particles, they became incorporated into these particles when expressed with VP1 in Sf9 cells. Recombinant particles with different polyomavirus structural protein(s) were obtained by using different combined expression of these proteins in Sf9 cells. Cellular DNA of 5 kbp in size was packaged in all of the recombinant particles, which showed the same diameter as that of native virions. Agarose gel electrophoresis indicated that DNA packaged in these recombinant particles had a different pattern than that of native virions. Two-dimensional gel electrophoresis of the VP1 species of recombinant particles showed more VP1 species than those of the native virions from mouse cells, and an additional species of VP1 when VP2 was co-expressed with VP1. The recombinant particles were also compared for their ability to compete for polyomavirus infection. The competition assay indicated that the recombinant particles containing VP2 were the most efficient in inhibiting the native polyomavirus infection of 3T6 cells.

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“…Namba et al (1988) described a related method to enhance displays of macromolecules, in which a smooth gradient of color is added to provide radialdepth cueing (R cueing) from the center of quasispherical structures (e.g., icosahedral viruses) or from the central axis of quasi-cylindrical structures (e.g., helical filaments). Salunke et al (1989) used this same style of R cueing in a computer-created model for polyomavirus virions. More recently, Grant et al (1992) used radial color gradients to highlight topographical features on the surfaces of small icosahedral viruses analyzed by X-ray crystallography.…”

Section: Introductionmentioning

confidence: 99%