title: Spherical plant viruses: interactions in solution, phase diagrams and crystallization of brome mosaic virus.
abstract: Brome mosaic virus (BMV) is a small icosahedral plant virus of mean diameter 268 A. Interactions between BMV particles in solution were studied by means of small-angle X-ray scattering in order to find crystallization conditions. The interactions between biomacromolecules as large as these viruses have not yet been systematically studied by this method. As it is known that usually proteins crystallize in, or close to, attractive regimes, the interactions between BMV particles in solution were studied as a function of pH, type of salt and size and concentration of polyethylene glycol. An unexpected result of these studies is that the precipitates obtained upon addition of PEG alone or PEG combined with salt were in fact made of microcrystals, which were all characterized by the same series of diffraction peaks, with positions close to those of a centered cubic space group. A phase diagram of the virus as a function of PEG concentration was established by means of microbatch experiments. From the precipitation zones, conditions for crystallization were tested from 5 to 40 mg ml(-1) virus with 3-10%(w/v) PEG 8000 or PEG 20,000. Small crystals were obtained in several conditions after a few days and continued growing for several weeks.
authors.affiliation: Bio Informatique Structurale, Centre de Génétique Moléculaire, Laboratoire Associé à l'Université Pierre et Marie Curie, Case 11, Université Pierre et Marie Curie, 7 Quai St Bernard, 75252 Paris CEDEX 05, France.
authors.forename: M
authors.initials: M
authors.lastname: Casselyn
authors.forename: J
authors.initials: J
authors.lastname: Perez
authors.forename: A
authors.initials: A
authors.lastname: Tardieu
authors.forename: P
authors.initials: P
authors.lastname: Vachette
authors.forename: J
authors.initials: J
authors.lastname: Witz
authors.forename: H
authors.initials: H
authors.lastname: Delacroix
mesh_terms: D017795:Bromovirus / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010942:Plant Viruses / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011487:Protein Conformation; D012492:Salts; D014771:Virion / Q000737:chemistry
chemical_list: D012492:Salts; D011092:Polyethylene Glycols