Efficient translation of the coat protein cistron of tobacco mosaic virus in a cell-free system from Escherichia coli.

Translation of tobacco mosaic virus (TMV) RNA in a cell-free system derived from Escherichia coli (MRE 600) reveals several discrete polypeptides in the Mr range of 10,000-50,000. The major product is a polypeptide of Mr 17,500 which comigrates with authentic TMV coat protein on sodium dodecyl sulphate/polyacrylamide gel electrophoresis. Structural investigations by peptide-mapping techniques and differential radiolabelling confirm that the major product is TMV coat protein with an N-terminal methionine. The major polypeptide product can be assembled in vitro into virus-like ribonucleoprotein particles. The structural and evolutionary implications of this observation, and the values of TMV in elucidating eukaryotic mRNA interactions with the prokaryotic protein-synthesizing machinery, are discussed.