Translation of brome mosaic viral ribonucleic acid in a cell-free system derived from wheat embryo.

The four RNAs of brome mosaic virus induce substantial incorporation of amino acids into protein when used as messengers in a cell-free protein-synthesizing system derived from wheat embryo. RNA 4 is highly efficient as a monocistronic messenger for the viral coat protein. Acetate, derived from acetyl coenzyme A, is incorporated into the product made in vitro. Although RNA 3 also contains the coat-protein cistron, it induces synthesis mostly of a protein larger than coat protein. RNAs 1 and 2 also induce the synthesis of substantial amounts of protein other than coat protein. However, an equimolar mixture of RNAs 3 and 4 or of 1, 2, 3, and 4 induces synthesis of coat protein almost exclusively. This result suggests that the coat-protein cistron, when present as a monocistronic messenger, inhibits translation of all other viral messages.