Conformational changes preceding decapsidation of bromegrass mosaic virus under hydrostatic pressure: a small-angle neutron scattering study 1 1Edited by D. Rees

Leimkühler, Martina; Goldbeck, A.; Lechner, M. D.; Witz, Jean‐François

doi:10.1006/jmbi.2000.3538

Cited by 23 publications

(17 citation statements)

References 57 publications

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“…Recent studies have demonstrated intermediate states in the assembly and disassembly pathway of many viruses, and protein-nucleic acid interactions appear to remain intact under pressure (32,(37)(38)(39). Our results with Sindbis and influenza viruses show that although pressure can preserve most of the physical properties of the envelope, it causes exposure of hydrophobic domains that populate the fusion-active state that may account for the pronounced inactivation.…”

Section: Fusion Of Sindbis Virus With Erythrocyte Ghosts After Virus mentioning

confidence: 56%

Hydrostatic Pressure Induces the Fusion-active State of Enveloped Viruses

Gaspar¹,

Silva²,

Gomes³

et al. 2002

Journal of Biological Chemistry

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Enveloped animal viruses must undergo membrane fusion to deliver their genome into the host cell. We demonstrate that high pressure inactivates two membrane-enveloped viruses, influenza and Sindbis, by trapping the particles in a fusion-intermediate state. The pressure-induced conformational changes in Sindbis and influenza viruses were followed using intrinsic and extrinsic fluorescence spectroscopy, circular dichroism, and fusion, plaque, and hemagglutination assays. Influenza virus subjected to pressure exposes hydrophobic domains as determined by tryptophan fluorescence and by the binding of bis-8-anilino-1-naphthalenesulfonate, a well established marker of the fusogenic state in influenza virus. Pressure also produced an increase in the fusion activity at neutral pH as monitored by fluorescence resonance energy transfer using lipid vesicles labeled with fluorescence probes. Sindbis virus also underwent conformational changes induced by pressure similar to those in influenza virus, and the increase in fusion activity was followed by pyrene excimer fluorescence of the metabolically labeled virus particles. Overall we show that pressure elicits subtle changes in the whole structure of the enveloped viruses triggering a conformational change that is similar to the change triggered by low pH. Our data strengthen the hypothesis that the native conformation of fusion proteins is metastable, and a cycle of pressure leads to a final state, the fusion-active state, of smaller volume.Enveloped viruses utilize regulated membrane fusion to introduce their genomes in the cytoplasm of the host cell. The fusion is mediated by surface envelope proteins of the virus in response to a trigger (1, 2). Once triggered, the fusion process leads to a conformational change that promotes the interaction of a specific sequence (fusion peptide) with the target membrane and initiates membrane fusion. Membrane fusion is crucial in other biological functions such as myotube formation, fertilization, and trafficking of endocytic and exocytic vesicles within eukaryotic cells (1, 3). Many enveloped animal viruses have been studied as models for understanding the mechanism of membrane fusion. While the fusion proteins of many viruses reveal significant similarity in their putative fusogenic conformation, such as those of influenza virus (hemagglutinin HA2), 1 human immunodeficiency virus (gp41 protein), Moloney murine leukemia virus (TM protein), and Ebola virus (GP2 protein) (4), the events of membrane fusion for other virus families (e.g. Flaviviridae and Togaviridae) are beginning to be understood. Alphavirus and the flavivirus fusion proteins appear to have evolved from a common ancestor (5) and possess a similar new class of membrane fusion proteins that do not form coiledcoils (6 -8).Sindbis and influenza are enveloped viruses that first enter a cell by endocytosis and then fuse with the cellular membrane in response to acidic conditions. Sindbis virus is the prototype of the Alphavirus genus, Togaviridae family. The Alphavirus spike is...

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Section: Fusion Of Sindbis Virus With Erythrocyte Ghosts After Virus mentioning

confidence: 56%

Hydrostatic Pressure Induces the Fusion-active State of Enveloped Viruses

Gaspar¹,

Silva²,

Gomes³

et al. 2002

Journal of Biological Chemistry

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“…These may facilitate the observed capsid swelling preceding irreversible disruption of the virus shell. 7,21 The presence of stabilizing Mg ions, which serve as lynchpins at 5-fold and quasi-3-fold axes, would explain how cations stabilize the capsid above neutral pH. In the absence of these ions, increased pH would promote repulsive interactions, thereby causing the capsid to dissociate.…”

Section: Resultsmentioning

confidence: 99%

The crystallographic structure of brome mosaic virus

Lucas

Larson

McPherson

2002

Journal of Molecular Biology

136

181

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The structure of brome mosaic virus (BMV), the type member of the bromoviridae family, has been determined from a single rhombohedral crystal by X-ray diffraction, and re®ned to an R value of 0.237 for data in the range 3.4-40.0 A Ê . The structure, which represents the native, compact form at pH 5.2 in the presence of 0.1 M Mg 2 , was solved by molecular replacement using the model of cowpea chlorotic mottle virus (CCMV), which BMV closely resembles. The BMV model contains amino acid residues 41-189 for the pentameric capsid A subunits, and residues 25-189 and 1-189 for the B and C subunits, respectively, which compose the hexameric capsomeres. In the model there are two Mg ions and one molecule of polyethylene glycol (PEG). The ®rst 25 amino acid residues of the C subunit are modeled as polyalanine. The coat protein has the canonical``jellyroll'' b-barrel topology with extended amino-terminal polypeptides as seen in other icosahedral plant viruses. Mass spectrometry shows that in native BMV virions, a signi®cant fraction of the amino-terminal peptides are apparently cleaved. No recognizable nucleic acid residue is visible in the electron density maps except at low resolution where it appears to exhibit a layered arrangement in the virion interior. It is juxtaposed closely with the interior surface of the capsid but does not interpenetrate. The protein subunits forming hexameric capsomeres, and particularly dimers, appear to interact extensively, but the subunits otherwise contact one another sparsely about the 5-fold and quasi 3-fold axes. Thus, the virion appears to be an assembly of loosely associated hexameric capsomeres, which may be the basis for the swelling and dissociation that occurs at neutral pH and elevated salt concentration. A Mg ion is observed to lie exactly on the quasi-3-fold axis and is closely coordinated by side-chains of three quasi-symmetry-related residues glutamates 84, with possible participation of side-chains from threonines 145, and asparagines 148. A presumptive Mg 2 is also present on the 5-fold axis where there is a concentration of negatively charged side-chains, but the precise coordination is unclear. In both cases these cations appear to be essential for maintenance of virion stability. Density that is contiguous with the viral interior is present on the 3-fold axis at the center of the hexameric capsomere, where there is a pore of about 6 A Ê diameter. The density cannot be attributed to cations and it was modeled as a PEG molecule.

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“…The presence of salt in the buffer does not greatly affect the scattering properties for neutrons. Thus, SANS has an advantage over SAXS; simply by changing the ratio of H 2 O to D 2 O in the solvent, one can create contrast matching condition, making it much easier to distinguish between protein and hydrated RNAs [13,14]. The possibility that D 2 O may affect the stability or the structure of the virus must be checked in each case, but D 2 O is less likely to have and effect than high salt concentrations.…”

Section: Introductionmentioning

confidence: 99%

Small Angle Scattering Study of the Structure and Organization of RNAs and Protein of Brome Mosaic Virus (BMV) Capsid Protein

et al. 2014

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Brome mosaic virus (BMV) viron is a model system that has a small icosahedral capsid protein (CP) shell. It is well known that BMV is plant virus which is a member of the alpha virus-like superfamily group. These viruses have genetic material and nucleic acids (RNA) with a segmented positive-strand RNA that offers high levels of RNA synthesis and virus production in plants. BMV CP tightly regulates the packaging of its RNAs into the inner core of the capsid while maintaining an outer protein shell coat. Small angle neutron scattering (SANS) and small angle Xray scattering (SAXS) were applied to study the size, shape and protein-RNAs organization of BMV CP. BMV capsid protein and buffer solution containing a D 2 O/H 2 O mixture was used to enhance the contrast of the material for neutron scattering measurements. The pair distance distribution P(r) of BMV CP from the indirect Fourier transform of scattering spectrum was able to illustrate the differences in the distribution of materials, signifying RNAs packing, and protein in the BMV CP. The extracted parameter from P(r) shows that the BMV CP is about 260 Å in diameter and is composed of RNA with ~ 74 Å core radiuses and coated protein shell of thickness 56 Å. The contribution of RNAs core, protein shell was estimated by simulation. The contribution due to interference of core and shell called cross term was also extracted from simulation.

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Conformational changes preceding decapsidation of bromegrass mosaic virus under hydrostatic pressure: a small-angle neutron scattering study 1 1Edited by D. Rees

Cited by 23 publications

References 57 publications

Hydrostatic Pressure Induces the Fusion-active State of Enveloped Viruses

Hydrostatic Pressure Induces the Fusion-active State of Enveloped Viruses

The crystallographic structure of brome mosaic virus

Small Angle Scattering Study of the Structure and Organization of RNAs and Protein of Brome Mosaic Virus (BMV) Capsid Protein

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