Figure 3

Expression of pol directed by the isolated gag-pol junction region is predominantly independent of gag translation. The Tca2 gag-pol junction region was cloned in between translationally-fused lacZ and luc genes in the dual reporter vector pAC98 (Materials and Methods). Panel A: the bar chart shows the normalised level of downstream luc gene expression in constructs transformed with the parental vector pAC98 (control lacZ-luc), wild-type Tca2 stop and sense variants (pGRE1 and 2), junction variants with three in-frame stop codons or three CAA (Gln) codons, respectively, cloned at the 3' end of lacZ (pGRE5 and 6), junction variants with the luc ORF placed in the -1 frame with respect to lacZ (pGRE 7 and 8), and junction variants with three -1 frame AUG codons followed immediately by a -1 frame stop codon, introduced at the 5' end of the luc ORF (pGRE 3 and 4). Constructs are depicted schematically in panel B, and panel C indicates the positions of relevant natural AUG codons found in the 0 (*) and +1 frames (+) in the wildtype, non-mutagenised, Tca2 junction region (see text for details). Bars represent means normalised luciferase activities of independent transformants +/- 1 standard deviation (n = 3).