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1.
Virology ; 373(1): 61-71, 2008 Mar 30.
Article in English | MEDLINE | ID: mdl-18155742

ABSTRACT

We found that a 2-h incubation of potato virus X (PVX) virions in 10 mM Tris-HCl buffer pH 7.5 at -20 degrees C results in a strong but reversible drop in virion stability. Under these conditions, the PVX virions are completely disrupted by low (starting from 50 mM) concentrations of LiCl and CaCl(2) but not of NaCl. Incubation of PVX samples with 0.05-2 M LiCl at +4 degrees C did not result in virion disassembly and the virions were not disrupted upon incubation at -20 degrees C in 10 mM Tris-HCl buffer pH 7.5 without LiCl. We suggest that a 2-h incubation of the PVX virions at -20 degrees C in 10 mM Tris-HCl pH 7.5 results in a structural transition in the virus particles. A revised model of the three-dimensional organization of coat protein subunits in the PVX virions is proposed. This two-domain model explains better the high plasticity of the PVX CP structure.


Subject(s)
Capsid Proteins , Models, Chemical , Potexvirus/chemistry , Virion/chemistry , Buffers , Calorimetry, Differential Scanning , Capsid Proteins/chemistry , Capsid Proteins/isolation & purification , Capsid Proteins/metabolism , Circular Dichroism , Fluorescence , Hydrochloric Acid/pharmacology , Potexvirus/metabolism , Virion/metabolism , Virology/methods , Virus Assembly
2.
Macromol Biosci ; 8(2): 199-209, 2008 Feb 11.
Article in English | MEDLINE | ID: mdl-17886326

ABSTRACT

The interactions of non-ionic surfactant Triton X-100 and the coat protein of tobacco mosaic virus, which is an established model for both ordered and non-ordered protein aggregation, were studied using turbidimetry, differential scanning calorimetry, isothermal titration calorimetry, and dynamic light scattering. It was found that at the critical aggregation concentration (equal to critical micelle concentration) of 138 x 10(-6) M, Triton X-100 induces partial denaturation of tobacco mosaic virus coat protein molecules followed by protein amorphous aggregation. Protein aggregation has profound ionic strength dependence and proceeds due to hydrophobic sticking of surfactant-protein complexes (start aggregates) with initial radii of 46 nm. It has been suggested that the anionic surfactant sodium dodecyl sulfate forms mixed micelles with Triton X-100 and therefore reverses protein amorphous aggregation with release of protein molecules from the amorphous aggregates. A stoichiometric ratio of 5 was found for Triton X-100-sodium dodecyl sulfate interactions.


Subject(s)
Capsid Proteins/chemistry , Micelles , Octoxynol/chemistry , Surface-Active Agents/chemistry , Tobacco Mosaic Virus/chemistry , Calorimetry, Differential Scanning , Chemistry, Physical/methods , Nephelometry and Turbidimetry , Sodium Dodecyl Sulfate/chemistry
3.
Int J Biochem Cell Biol ; 38(4): 533-43, 2006.
Article in English | MEDLINE | ID: mdl-16318921

ABSTRACT

Ordered and amorphous protein aggregation causes numerous diseases. Tobacco mosaic virus coat protein for many decades serves as the classical model of ordered protein aggregation ("polymerization"). It was also found to be highly prone to heat-induced amorphous aggregation and the rate of this aggregation could be easily manipulated by changes in solution ionic strength and temperature. Here, we report that rapid amorphous aggregation of this protein can be induced at 25 degrees C in phosphate buffer by low micromolar (start at about 15 microM) concentrations of cationic surfactant cetyltrimethylammonium bromide. At equilibrium four surfactant molecules bound to the protein subunit. As judged by circular dichroism and fluorescence spectroscopy data, the coat protein molecules retained their native structure upon the cetyltrimethylammonium bromide induced aggregation. No aggregation was observed at the higher surfactant concentrations (above 300 microM). Micromolar concentrations of anionic surfactant sodium dodecylsulfate rapidly reversed the cetyltrimethylammonium bromide induced aggregation of the coat protein due to formation of mixed surfactant-surfactant micelles. Cetyltrimethylammonium bromide (100-300 microM) also induced the reversible intact tobacco mosaic virus virion aggregation. The possible liability to the cetyltrimethylammonium bromide induced amorphous aggregation of other ordered aggregate-producing proteins has been discussed.


Subject(s)
Capsid Proteins/chemistry , Cetrimonium Compounds/chemistry , Tobacco Mosaic Virus/chemistry , Cetrimonium
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