Expression of the large 5'-proximal cistron of tobacco mosaic virus by 70 S ribosomes during cotranslational disassembly in a prokaryotic cell-free system.
In vitro translation of pH 8-washed particles of tobacco mosaic virus (TMV; vulgare, common, or U1 strain) in a cell-free system derived from Escherichia coli (MRE 600) results in a broad size range of TMV RNA-encoded products, including significant amounts of the distinctive 126-kDa polypeptide which is encoded by the first, 5'-proximal open reading frame in TMV RNA and is conventionally expressed by 80 S eukaryotic ribosomes. In an identical prokaryotic translation system, unencapsidated TMV RNA encodes a series of polypeptides of 50 kDa or less. The predominant product of 16-17 kDa frequently appears to comigrate with TMV coat protein. The significance of the former result for mRNA-ribosome interactions and for possible virus-uncoating/early gene expression events within the chloroplasts of infected cells is discussed.
Wilson
T M
TM
Department of Virus Research, John Innes Institute, Colney Lane, Norwich NR4 7UH, United Kingdom.