The 3'-terminus of RNA from several viruses can bind specific amino acids in a tRNA-like manner. Examples are tyrosylation of RNA components from brome mosaic virus (BMV), valine binding by RNA from turnip yellow mosaic virus (TYMV), and histidine binding by tobacco mosaic virus (TMV) RNA. Objectives of this project are to characterize the reaction, to determine if these viral RNAs have a tRNA-like ability to donate bound amino acid, and to investigate the biological significance of this reaction in relation to infectivity. Previously, synthetase enzymes and tRNA used in these studies have been from several sources; since heterologous systems can sometimes yield misleading results, we are undertaking preparation of synthetases and tRNA from wheat, which is a natural host for BMV and which is the source of the cell-free protein-synthesizing system we use. A ternary complex between aminoacylated viral RNA and elongation factor EF1 has been reported for TYMV RNA and TMV RNA. We plan to find if BMV RNA will participate in such a complex, and if this complex functions in relation to replication (EF1 is a reportedly identical with subunit III of Q beta replicase) or if it will bind to ribosomes - and if so, whether such binding is to the 40S or the 60S ribosomal subunit. The possibility that, under favorable conditions, charged viral RNA can donate the bound amino acid to nascent polypeptide will be further examined. A comparison of the infectivity of 3'-blocked and chargable viral RNA will be undertaken.