Topic
Viral outer capsid
About: Viral outer capsid is a research topic. Over the lifetime, 41 publications have been published within this topic receiving 3207 citations.
Papers
TL;DR: Three structural forms of type 1 Lang reovirus (virions, intermediate subviral particles [ISVPs], and cores) have been examined by cryoelectron microscopy and image reconstruction at 27 to 32-A resolution to reveal dramatic changes in supra-molecular structure and protein conformation that are related to the early steps of reov virus infection.
Abstract: Three structural forms of type 1 Lang reovirus (virions, intermediate subviral particles [ISVPs], and cores) have been examined by cryoelectron microscopy (cryoEM) and image reconstruction at 27 to 32-A resolution. Analysis of the three-dimensional maps and known biochemical composition allows determination of capsid protein location, globular shape, stoichiometry, quaternary organization, and interactions with adjacent capsid proteins. Comparisons of the virion, ISVP and core structures and examination of difference maps reveal dramatic changes in supra-molecular structure and protein conformation that are related to the early steps of reovirus infection. The intact virion (approximately 850-A diam) is designed for environmental stability in which the dsRNA genome is protected not only by tight sigma 3-mu 1, lambda 2-sigma 3, and lambda 2-mu 1 interactions in the outer capsid but also by a densely packed core shell formed primarily by lambda 1 and sigma 2. The segmented genome appears to be packed in a liquid crystalline fashion at radii < 240 A. Depending on viral growth conditions, virions undergo cleavage by enteric or endosomal/lysosomal proteases, to generate the activated ISVP (approximately 800-A diam). This transition involves the release of an outer capsid layer spanning radii from 360 to 427 A that is formed by 60 tetrameric and 60 hexameric clusters of ellipsoidal subunits of sigma 3. The vertex-associated cell attachment protein, sigma 1, also undergoes a striking change from a poorly visualized, more compact form, to an extended, flexible fiber. This conformational change may maximize interactions of sigma 1 with cell surface receptors. Transcription of viral mRNAs is mediated by the core particle (approximately 600-A diam), generated from the ISVP after penetration and uncoating. The transition from ISVP to core involves release of the 12 sigma 1 fibers and the remaining outer capsid layer formed by 200 trimers of rod-shaped mu 1 subunits that span radii from 306 to 395 A. In the virion and ISVP, flower-shaped pentamers of the lambda 2 protein are centered at the vertices. In the ISVP-to-core transition, domains of the lambda 2 subunits rotate and swing upward and outward to form a turret-like structure extending from radii 305 to 400 A, with a diameter of 184 A, and a central channel 84 A wide. This novel conformational change allows the potential diffusion of substrates for transcription and exit of newly synthesized mRNA segments.(ABSTRACT TRUNCATED AT 400 WORDS)
349 citations
TL;DR: The structure of μ1, complexed with its “protector” protein, σ3, and the fit of this μ13σ33 heterohexameric complex into the cryoEM image of an intact virion, reveal molecular events essential for viral penetration.
232 citations
TL;DR: Parental reovirus is not completely uncoated after infection to yield free genome RNA, instead it is converted into a subviral particle which contains besides 10 segments of double-stranded RNA and A-rich RNA, all core polypeptides namely λ1, λ2, μ1, and σ2 and aPolypeptide with a molecular weight of 65,000 which is derived from the outer capsomere protein μ2 by cleavage.
161 citations
TL;DR: A detailed picture of the molecular basis of reovirus virulence and attenuation is emerging and three proteins are identified that are responsible for inhibiting cell macromolecular synthesis.
Abstract: The pathogenesis of infection of mice by the mammalian reoviruses involves several discrete steps. Each of the three viral outer capsid proteins has a highly distinct and specialized role: one protein (σ1) binds to cell surface receptors; a second protein (µ1C) determines the capacity for viral growth at mucosal surfaces; and the third protein (σ3) is responsible for inhibiting cell macromolecular synthesis. A detailed picture of the molecular basis of reovirus virulence and attenuation is now emerging.
130 citations
TL;DR: The results indicate that both cells and viruses evolve mutations that affect one or more early steps in the viral growth cycle during maintenance of L-cell cultures persistently infected with reoviruses.
Abstract: Previous studies demonstrated that both cellular and viral mutants are selected during maintenance of persistent infections established in murine L cells with high-passage stocks of mammalian reoviruses. In particular, when one culture was cured of persistent infection, the resulting cells were found to support the growth of viruses isolated from persistently infected cultures (termed PI viruses here) better than that of wild-type (wt) viruses (R. Ahmed, W. M. Canning, R. S. Kauffman, A. H. Sharpe, J. V. Hallum, and B. N. Fields, Cell 25:325-332, 1981). To address the nature of cellular and viral mutations selected during maintenance of persistent reovirus infections, we established independent, persistently infected cultures with L cells and high-passage stocks of wt reovirus. These cultures served as sources of new PI viruses and cured cells for study. We found that although wt viruses grew poorly in cured cells when infection was initiated with intact virions, they grew well in cured cells when infection was initiated with infectious subvirion particles generated from virions by in vitro treatment with chymotrypsin. This finding indicates that the block to growth of wt viruses in cured cells involves an early step that is unique to infection by virions, such as proteolytic processing in an endocytic compartment. We also found that PI viruses grew better than wt viruses in L cells treated with ammonium chloride, a weak base that inhibits the pH decrease in endosomes and lysosomes. Because ammonium chloride blocks an early step in infection by intact virions, probably the proteolytic processing of viral outer capsid proteins by acid-dependent cellular proteases in late endosomes or lysosomes, this finding indicates that PI viruses differ from wt viruses with respect to viral entry into cells. Therefore, these results indicate that both cells and viruses evolve mutations that affect one or more early steps in the viral growth cycle during maintenance of L-cell cultures persistently infected with reoviruses.
95 citations
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Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 2 |
| 2019 | 1 |
| 2016 | 3 |
| 2015 | 1 |
| 2012 | 3 |
| 2011 | 1 |