STUDY OF BARLEY STRIPE MOSAIC-VIRUS (BSMV) GENOME .2. TRANSLATION OF INDIVIDUAL RNA SPECIES OF 2 BSMV STRAINS IN A HOMOLOGOUS CELL-FREE SYSTEM

The products of in vitro translation of individual RNA species of two strains of barley stripe mosaic virus (BSMV) were analyzed. The Russian strain contained two and the Norwich strain three components of virion RNA, designated RNAs 1-3 in the order of decreasing molecular weight. Each of these RNA species was purified and used to direct protein synthesis in a cell-free system from wheat embryos. Translation of RNA1 of both BSMV strains resulted in the production of one major polypeptide of a molecular weight of about 120,000. This polypeptide represents about 70% of the coding capacity of RNA1. RNA2 of the Norwich strain directed synthesis of essentially one product, the virus coat protein. The identity of the coat protein was shown by coelectrophoresis on discontinuous polyacrylamide slab gel, by specific immunoprecipitation and coincidence between tryptic peptide fingerprints. The coat protein gene represents only 15% of the coding potential of RNA2 Norwich; this means that the greater part of this RNA is not translated in vitro. On the other hand, RNA2 of the Russian strain was translated in vitro as two polypeptides, the coat protein and a polypeptide of a molecular weight of about 85,000. It should be emphasized that the greater part of the nucleotide sequence of RNA2 and 3 Norwich are doubled (see accompanying paper). Unexpectedly, the coding specificity of these RNAs in vitro was quite different. Translation of RNA3 (Norwich strain) yielded one major product of a molecular weight of about 75,000. A tentative model of the BSMV genome is proposed. © 1979 Springer-Verlag.