Cell-free Translation of Beet Necrotic Yellow Vein Virus: Readthrough of the Coat Protein Cistron

RNA from isolate F13 of beet necrotic yellow vein virus, an isolate that lacks RNA-4, has been translated in a rabbit reticulocyte lysate. Abundant translation products of RNA-1 had molecular weights of 150 000 (150K) and 50K. RNA-2 directed synthesis of the 22K viral coat protein and an 85K polypeptide. Both RNA-2 translation products were precipitated by antiserum against virus. The time course of appearance of the 22K and 85K polypeptides, comparative peptide mapping, and translation experiments with added suppressor tRNA indicate that the cistron for the 22K viral coat protein is situated near the 5′ terminus of RNA-2 and that the 85K polypeptide arises by partial readthrough of the coat protein cistron.