Functionality of the STNV translational enhancer domain correlates with affinity for two wheat germ factors

The satellite tobacco necrosis virus RNA is uncapped and requires a 3' tran slational enhancer domain (TED) for translation, Both in the wheat germ ext ract and in tobacco, TED stimulates in cis translation of heterologous, unc apped RNAs. In this study we investigated to what extent translation stimul ation by TED depends on binding to wheat germ factors, We show that in vitr o TED binds at least seven wheat germ proteins. Translation and crosslinkin g assays, to which TED or TED derivatives with reduced functionality were i ncluded as competitor, showed that TED function correlates with binding to a 28 kDa protein (p28), One particular condition of competition revealed th at p28 binding is not obligatory for TED function. Under this condition, a 30 kDa protein (p30) binds to TED, Importantly, affinity of p30 correlates with functionality of TED, These results strongly suggest that TED has the capacity to stimulate translation by recruiting the translational machinery either via binding to p28 or via binding to p30.