The Metastable State of Nucleocapsids of Enveloped Viruses as Probed by High Hydrostatic Pressure

Enveloped viruses fuse their membranes with cellular membranes to transfer their genomes into cells at the beginning of infection. What is not clear, however, is the role of the envelope (lipid bilayer and glycoproteins) in the stability of the viral particle. To address this question, we compared t...

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Bibliographic Details
Published in:	The Journal of biological chemistry Vol. 276; no. 10; pp. 7415 - 7421
Main Authors:	Gaspar, Luciane P., Terezan, Alexandre F., Pinheiro, Anderson S., Foguel, Débora, Rebello, Moacyr A., Silva, Jerson L.
Format:	Journal Article
Language:	English
Published:	United States Elsevier Inc 09-03-2001 American Society for Biochemistry and Molecular Biology
Subjects:	Alphavirus Alphavirus - metabolism Anilino Naphthalenesulfonates - pharmacology Animals Cell Line Cell Membrane - chemistry Cell Membrane - metabolism Chromatography, Gel Chromatography, High Pressure Liquid Cricetinae Ethidium - pharmacology Fluorescent Dyes - pharmacology Hydrostatic Pressure Light Models, Biological Nucleocapsid Proteins - chemistry Pressure Protein Binding Scattering, Radiation Spectrometry, Fluorescence Tryptophan - metabolism Urea - metabolism Urea - pharmacology Viruses - chemistry
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Summary:	Enveloped viruses fuse their membranes with cellular membranes to transfer their genomes into cells at the beginning of infection. What is not clear, however, is the role of the envelope (lipid bilayer and glycoproteins) in the stability of the viral particle. To address this question, we compared the stability between enveloped and nucleocapsid particles of thealphavirus Mayaro using hydrostatic pressure and urea. The effects were monitored by intrinsic fluorescence, light scattering, and binding of fluorescent dyes, including bis(8-anilinonaphthalene-1-sulfonate) and ethidium bromide. Pressure caused a drastic dissociation of the nucleocapsids as determined by tryptophan fluorescence, light scattering, and gel filtration chromatography. Pressure-induced dissociation of the nucleocapsids was poorly reversible. In contrast, when the envelope was present, pressure effects were much less marked and were highly reversible. Binding of ethidium bromide occurred when nucleocapsids were dissociated under pressure, indicating exposure of the nucleic acid, whereas enveloped particles underwent no changes. Overall, our results demonstrate that removal of the envelope with the glycoproteins leads the particle to a metastable state and, during infection, may serve as the trigger for disassembly and delivery of the genome. The envelope acts as a “Trojan horse,” gaining entry into the host cell to allow release of a metastable nucleocapsid prone to disassembly.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	0021-9258 1083-351X
DOI:	10.1074/jbc.M010037200