Efficient Translation of the Coat Protein Cistron of Tobacco Mosaic Virus in a Cell‐Free System from Escherichia coli

Abstract

Translation of tobacco mosaic virus (TMV) RNA in a cell-free system derived from E. coli (MRE 600) reveals several discrete polypeptides in the MW range of 10,000-50,000. The major product is a polypeptide of MV 17,500 which comigrates with authentic TMV coat protein on sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Structural investigations by peptide-mapping techniques and differential radiolabeling 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.