FEATURES OF THE AUTONOMOUS FUNCTION OF THE TRANSLATIONAL ENHANCER DOMAIN OF SATELLITE TOBACCO NECROSIS VIRUS

The RNA of satellite tobacco necrosis virus (STNV) is a monocistronic messenger that lacks both a cap and a poly(A) tail. Translation of STN V RNA in vitro is promoted by a 120-nt translational enhancer domain ( TED) in the 3'-untranslated region. TED also stimulates translation of heterologous mRNAs. In this study, we show that TED stimulates transl ation of a cat mRNA by increasing translation efficiency to the level of capped mRNA. This stimulatory activity is not impaired by translati on through TED. TED stimulates translation efficiency from different p ositions within the mRNA, varying from the 5' end to 940 nt downstream of the coding region. Duplication of TED has an additive effect on tr anslation stimulation only when located at both ends of the mRNA. On d icistronic RNAs, TED stimulates translation of both cistrons to the sa me extent. These data suggest that TED acts primarily by recruiting th e translational machinery to the RNA.