[69] In Vitro Translation of STNV-RNA

Satellite tobacco necrosis virus (STNV) is a degenerate virus requiring in vivo coinfection with tobacco necrosis virus (TNV) for growth. This unique dependence is assumed to arise from the fact that STNV-RNA contains information for only STNV coat protein. STNV replication, in vivo, is then assumed to require TNV dependent enzymes (e.g., TNV dependent RNA replicase). The full details of this in vivo dependence are yet to be worked out. Yet various in vitro studies with STNV and STNV-RNA emphasize the uniqueness of the STNV system. STNV is a small virus (approximately 2 X 10⁶ daltons) containing one piece of 400,000 molecular weight single stranded RNA. This STNV-RNA serves as an in vitro messenger-RNA in both prokaryotic and eukaryotic systems. Further, in both systems, such translation results in in vitro synthesis of STNV coat protein. Thus STNV-RNA is a readily available, monocistronic, messenger-RNA capable of directing the synthesis of a single defined protein. Such an RNA has many uses in in vitro protein biosynthesis studies.