FIGURE 4.

Investigating the role of the 18S rRNA complementary region in termination–reinitiation. (A) Comparison of part of the sequence of helix 26 of 18S rRNA and complementary sequences present upstream of the termination–reinitiation sites of FCV, RHDV, and influenza B. Contiguous nucleotides complementary to the 18S rRNA are shown in italics. (B) Schematic of the mutants generated to address the role of the complementarity between the BM2 mRNA and the 18S rRNA. The sequence of the relevant region of 18S rRNA is shown and putative mRNA base pairing is marked, with the mRNA bases numbered relative to the stop codon of rlucM1. Mutations are shown in bold and underlined. (C) Plasmids were linearized, transcribed, translated, and analyzed according to the legend of Figure 3. Control translations (wt, ps) were performed in parallel. Lanes are labeled with the last two letters of each reporter plasmid name. The asterisked band in lane CC highlights the presence of the putative frameshift product in a translation lacking the BM2 product (see the text).