Comparison of capsids and nucleocapsids from cowpea mosaic virus-infected cowpea protoplasts and seedlings.
Extracts of Cowpea mosaic virus (CPMV)-infected Cowpea (Vigna unguiculata) protoplasts were applied to an anion-exchange agarose resin. Both capsid-like and virion-like particles (collectively designated D-VLP) were present in the nonabsorbed fraction, although purified capsids and virions from protoplasts and from plants were absorbed irreversibly under the same conditions. The larger of the two capsid proteins, L protein, behaved similarly during electrophoretic analyses regardless of protoplast or plant source. The other capsid protein, S, showed decreasing apparent molecular weight and increasing anionic charge when it was recovered from (1) D-VLP, (2) virus particles from protoplasts, and (3) virus particles from leaf tissue of young infections and (4) older infections of plants, in the order indicated. This series of four kinds of particles is postulated to be temporal, reflecting the progress of proteolytic processing events. The proteolysis affects the carboxyl terminal but not the amino terminal sequences of S protein from particles recovered from plants.
Kridl
J C
JC
Department of Biochemistry and Biophysics, University of California, Davis, California 95616, USA.
Bruening
G
G