JBC, Vol. 252, Issue 24, 9010-9017, Dec, 1977
Translation of the L-species dsRNA genome of the killer-associated virus-like particles of Saccharomyces cerevisiae
J. E. Hopper, K. A. Bostian, L. B. Rowe and D. J. Tipper
Virus-like particles containing the L (P1)-species of double-stranded RNA
(dsRNA) were isolated from Saccharomyces cerevisiae, and the translational
activity of the virus-like particle-derived dsRNA was analyzed in the wheat
germ cell-free system. Denaturation of the dsRNA immediately prior to in
vitro translation resulted in the synthesis of one major and at least three
minor polypeptides, whereas undenatured dsRNA, as expected, did not
stimulate [35S]methionine incorporation into polypeptides, but actually
slightly inhibited endogenous activity. The major in vitro translation
product of the denatured L-dsRNA was shown to be identical with the major
L-dsRNA containing virus-like particle capsid polypeptide on the basis of
three criteria: co-electrophoresis on sodium dodecyl sulfate polyacrylamide
gels, immunoprecipitation, and tryptic peptide analysis. We have therefore
established that the L-dsRNA genome encodes the major virus-like particle
capsid polypeptide. This result adds considerable support to the hypothesis
that the L-dsRNA genome acts as a helper genome to the smaller (1.6 x 10(6)
dalton) M-dsRNA genome in killer strains of yeast by providing the M-dsRNA
containing virus-like particles with their major coat protein.