A previously undetected subviral particle, designated the 55S particle because of its position in sucrose density gradients, has been found in cytoplasmic extracts of poliovirus-infected cells. It contains no RNA, is composed of equimolar amounts of the structural polypeptides PlAB, P1C, and P1D, and is stable in vitro under a variety of conditions: presence or absence of EDTA, dilution in low- or high-ionic-strength buffers, suspension -in buffers up to pH 10, incubation at 37°C, and centrifugation to equilibrium in CsCl gradients (where it bands at a density of 1.285 g/cm3). Conventional pulse-chase experiments show that 55S particles are the products of the assembly of 14S subunits and the precursors of virions. These data led to the formulation of a model of poliovirus morphogenesis in which the conversion of capsomers into 73S empty capsids does not occur directly, but through the formation of an intermediate structure, the 55S particle.
Characterization and role in morphogenesis of a new subviral particle (55S) isolated from polio infected cells
PANI, ALESSANDRA;
1987-01-01
Abstract
A previously undetected subviral particle, designated the 55S particle because of its position in sucrose density gradients, has been found in cytoplasmic extracts of poliovirus-infected cells. It contains no RNA, is composed of equimolar amounts of the structural polypeptides PlAB, P1C, and P1D, and is stable in vitro under a variety of conditions: presence or absence of EDTA, dilution in low- or high-ionic-strength buffers, suspension -in buffers up to pH 10, incubation at 37°C, and centrifugation to equilibrium in CsCl gradients (where it bands at a density of 1.285 g/cm3). Conventional pulse-chase experiments show that 55S particles are the products of the assembly of 14S subunits and the precursors of virions. These data led to the formulation of a model of poliovirus morphogenesis in which the conversion of capsomers into 73S empty capsids does not occur directly, but through the formation of an intermediate structure, the 55S particle.
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