Structural rearrangements in the membrane penetration protein of a non-enveloped virus

Dormitzer, Philip R.; Nason, Emma B.; Prasad, B. V. Venkataram; Harrison, Stephen C.

doi:10.1038/nature02836

Cited by 207 publications

(254 citation statements)

References 30 publications

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“…Nonenveloped viral particles must breach the membrane of a target host cell to gain access to its cytoplasm (30). How a nonenveloped virus enters a cell is poorly understood.…”

Section: Discussionmentioning

confidence: 99%

The P2 capsid protein of the nonenveloped rice dwarf phytoreovirus induces membrane fusion in insect host cells

Zhou

Wei

et al. 2007

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

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Insect transmission is an essential process of infection for numerous plant and animal viruses. How an insect-transmissible plant virus enters an insect cell to initiate the infection cycle is poorly understood, especially for nonenveloped plant and animal viruses. The capsid protein P2 of rice dwarf virus (RDV), which is nonenveloped, is necessary for insect transmission. Here, we present evidence that P2 shares structural features with membrane-fusogenic proteins encoded by enveloped animal viruses. When RDV P2 was ectopically expressed and displayed on the surface of insect Spodoptera frugiperda cells, it induced membrane fusion characterized by syncytium formation at low pH. Mutational analyses identified the N-terminal and a heptad repeat as being critical for the membrane fusion-inducing activity. These results are corroborated with results from RDV-infected cells of the insect vector leafhopper. We propose that the RDV P2-induced membrane fusion plays a critical role in viral entry into insect cells. Our report that a plant viral protein can induce membrane fusion has broad significance in studying the mechanisms of virus entry into insect cells and insect transmission of nonenveloped plant and animal viruses.

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“…Nonenveloped viral particles must breach the membrane of a target host cell to gain access to its cytoplasm (30). How a nonenveloped virus enters a cell is poorly understood.…”

Section: Discussionmentioning

confidence: 99%

The P2 capsid protein of the nonenveloped rice dwarf phytoreovirus induces membrane fusion in insect host cells

Zhou

Wei

et al. 2007

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

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“…Thus, a stoichiometry of 1 corresponds to 780 VP7 molecules and 180 VP4 molecules per DLP. The numbers of binding sites per DLP are based on evidence from electron cryomicroscopy and X-ray crystallography (18,44,58).…”

Section: Resultsmentioning

confidence: 99%

“…The spike protein VP4 is anchored in the DLP and protrudes through the VP7 layer (53,58). This protein undergoes a fold-back rearrangement that resembles the fusogenic rearrangements of enveloped virus fusion proteins (18), although the function of the VP4 conformational change has yet to be demonstrated experimentally.…”

mentioning

confidence: 99%

Assembly of Highly Infectious Rotavirus Particles Recoated with Recombinant Outer Capsid Proteins

Trask

Dormitzer

2006

J Virol

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109

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Assembly of the rotavirus outer capsid is the final step of a complex pathway. In vivo, the later steps include a maturational membrane penetration that is dependent on the scaffolding activity of a viral nonstructural protein. In vitro, simply adding the recombinant outer capsid proteins VP4 and VP7 to authentic doublelayered rotavirus subviral particles (DLPs) in the presence of calcium and acidic pH increases infectivity by a factor of up to 10 7 , yielding particles as infectious as authentic purified virions. VP4 must be added before VP7 for high-level infectivity. Steep dependence of infectious recoating on VP4 concentration suggests that VP4-VP4 interactions, probably oligomerization, precede VP4 binding to particles. Trypsin sensitivity analysis identifies two populations of VP4 associated with recoated particles: properly mounted VP4 that can be specifically primed by trypsin, and nonspecifically associated VP4 that is degraded by trypsin. A full complement of properly assembled VP4 is not required for efficient infectivity. Minimal dependence of recoating on VP7 concentration suggests that VP7 binds DLPs with high affinity. The parameters for efficient recoating and the characterization of recoated particles suggest a model in which, after a relatively weak interaction between oligomeric VP4 and DLPs, VP7 binds the particles and locks VP4 in place. Recoating will allow the use of infectious modified rotavirus particles to explore rotavirus assembly and cell entry and could lead to practical applications in novel immunization strategies.To initiate rotavirus infection, the nonenveloped, icosahedral, triple-layered particle (TLP or virion) must translocate a large transcriptionally active subviral particle, the double-layered particle (DLP), across a membrane and into the cytoplasm of a target cell. The DLP consists of concentric VP2 and VP6 icosahedral protein shells, which encapsidate 11 doublestranded RNA genome segments, the viral polymerase (VP1), and a capping enzyme (VP3). Biochemical and structural studies indicate that conformational rearrangements in VP4 and VP7, the two proteins that make up the outermost shell of the TLP, deliver the DLP into the cytoplasm. The dissociation of trimers of the plate-like protein VP7 in low-calcium environments mediates uncoating in vitro (17, 51). The spike protein VP4 is anchored in the DLP and protrudes through the VP7 layer (53,58). This protein undergoes a fold-back rearrangement that resembles the fusogenic rearrangements of enveloped virus fusion proteins (18), although the function of the VP4 conformational change has yet to be demonstrated experimentally.Because VP4 and VP7 are both targets of neutralizing antibodies, understanding the mechanism of cell entry is linked to understanding protection against rotavirus gastroenteritis, which kills approximately 500,000 children each year (43). The development of efficient techniques to incorporate recombinant VP4 and VP7 into infectious rotavirus virions would provide powerful tools to investigate how these ...

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“…VP8* is located as the outermost portion of the VP4 spike protein on the rotavirus virion and is associated with the antigenic specificity and genotype of VP4 (Dormitzer et al, 2004;Kapikian et al, 2001). The N termini of GAR VP2 are predicted to lie inside the core shell and to bind the viral enzyme-RNA complex (VP1-VP3-RNA) .…”

Section: Discussionmentioning

confidence: 99%

Analysis of genetic diversity and molecular evolution of human group B rotaviruses based on whole genome segments

Yamamoto

Ghosh

Ganesh

et al. 2010

Journal of General Virology

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Group B rotavirus (GBR) is a rare enteric pathogen that causes severe diarrhoea, primarily in adults. Nearly full-length sequences of all 11 RNA segments were determined for human GBRs detected recently in India (IDH-084 in 2007, IC-008 in 2008, Bangladesh (Bang117 in 2003) and Myanmar (MMR-B1 in 2007), and analysed phylogenetically with the sequence data of GBRs reported previously. All RNA segments of GBR strains from India, Bangladesh and Myanmar showed .95 % nucleotide sequence identities. Among the 11 RNA segments, the VP6 and NSP2 genes showed the highest identities (.98 %), whilst the lowest identities were observed in the NSP4 gene (96.1 %), NSP5 gene (95.6 %) and VP8*-encoding region of the VP4 gene (95.9 %). Divergent or conserved regions in the deduced amino acid sequences of GBR VP1-VP4 and NSP1-NSP5 were similar to those in group A rotaviruses (GARs), and the functionally important motifs and structural characteristics in viral proteins known for GAR were conserved in all of the human GBRs. These findings suggest that, whilst the degree of genetic evolution may be dependent on each RNA segment, human GBR may have been evolving in a similar manner to GAR, associated with the similar functional roles of individual viral proteins. INTRODUCTIONRotavirus, a member of the family Reoviridae, is the most important viral pathogen causing gastroenteritis in humans. Rotavirus has 11 segments of double-stranded RNA (dsRNA) as a genome, and the virus particle is composed of three concentric layers, i.e. the outer capsid, inner capsid and core (Estes & Kapikian, 2007). The outer capsid consists of two structural proteins, VP4 and VP7, which are neutralization antigens. The inner capsid consists of structural protein VP6. Rotavirus is classified into five groups (A-E) and two putative groups (F and G), based on the antigenicity of the inner capsid protein VP6 and genomic characteristics (Kapikian et al., 2001). In humans, groups A, B and C have so far been detected. Group A rotavirus (GAR) is the most prevalent throughout the world and is recognized as the leading viral pathogen of acute gastroenteritis in children.Group B rotavirus (GBR) is genetically and antigenically distinct from GAR and has been detected in humans, mice, calves, pigs and sheep. In humans, GBR has been noted because it causes severe, cholera-like diarrhoea, mostly in adults (Mackow, 1995). GBR was first identified as adult diarrhoea rotavirus (ADRV) in nationwide outbreaks in China in 1982-1983 (Hung et al., 1983, 1984Wang et al., 1985), and the detection of this virus has been limited to China (Dai et al., 1987; Fang et al., 1989). They were subsequently detected in sporadic cases in India in 1997 and in Bangladesh in 2000, demonstrating the distribution of GBRs in Asian countries outside China (Krishnan et al., 1999;Sanekata et al., 2003). Thereafter, GBRs have again been detected in these countries in sporadic cases of diarrhoea (Barman et al., 2006;Rahman et al., 2007). The GenBank/EMBL/DDBJ accession numbers for the nucleotide sequen...

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Structural rearrangements in the membrane penetration protein of a non-enveloped virus

Cited by 207 publications

References 30 publications

The P2 capsid protein of the nonenveloped rice dwarf phytoreovirus induces membrane fusion in insect host cells

The P2 capsid protein of the nonenveloped rice dwarf phytoreovirus induces membrane fusion in insect host cells

Assembly of Highly Infectious Rotavirus Particles Recoated with Recombinant Outer Capsid Proteins

Analysis of genetic diversity and molecular evolution of human group B rotaviruses based on whole genome segments

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