Translation of Tobacco Ringspot Virus RNA in Reticulocyte Lysate: Proteolytic Processing of the Primary Translation Products

Tobacco ringspot virus (TobRV) RNA was translated efficiently in rabbit reticulo-cyte lysate and directed the synthesis of two principal polypeptides, Mr 207 × 103 (207K) and l16K, corresponding to the translation products of RNA-1 and RNA-2 respectively. In addition, a l12K RNA-2-encoded polypeptide was sometimes detected. The l16K polypeptide was immunoprecipitated with anti-TobRV serum, suggesting that it was a precursor to coat protein. When translations were performed in the presence of dithiothreitol, the 207K polyprotein was apparently cleaved to yield 37K and 180K polypeptides, with additional processing into 65K and 128K polypeptides. Cleavage of the RNA-2-encoded polyprotein also occurred, although to a much lesser extent han that of the 207K polyprotein; polypeptides of 88K and 54K, both immunoprecipitated with antiviral serum, were identified as RNA-2-encoded cleavage products