Detection and cell-free translation of subgenomic RNAs of tobacco etch virus.
RNA extracted from purified tobacco etch virus and virus-infected tissue was examined by the northern hybridization technique and found to contain several subgenomic-sized viral RNA species in addition to the 3 x 10(6) MW genomic RNA. Of the 10 subgenomic-sized RNAs detected (2.03, 1.24, 1.14, 1.01, 0.84, 0.62, 0.55, 0.46, 0.34, and 0.28 x 10(6) MW), 4 were found in both virion RNA and infected tissue RNA, 3 others only in virion RNA, and 3 only in infected tissue RNA. Of the last three, two may be engendered during isolation by nuclease action on virion RNA, as indicated by controls. On the basis of their binding to oligo(dT) cellulose, all of the RNAs found in virus-infected tissue appeared to be polyadenylated. Cell-free translation of electrophoretically purified genome-length TEV RNA in a rabbit reticulocyte system stimulated the synthesis of a 39,000 MW polypeptide. In contrast, translation of unfractionated virion RNA in the reticulocyte system stimulated the production of a number of polypeptides; three of the principal products had molecular weights corresponding closely to those of known virus-encoded proteins. The predominant cell-free translation product of both electrophoretically purified genomic RNA and unfractionated virion RNA in the wheat germ system was a polypeptide with a molecular weight of 41,000. These findings are discussed in relation to a translation strategy for tobacco etch virus involving selective transcription or processing of genomic RNA to generate subgenomic RNAs that are then translated.
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Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202, USA.
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