Figure 4
trpXYZ mRNA contains a T-box riboswitch. (a) Visualization of the predicted trpX T-box riboswitch using T-box scan21. The specifier sequence that is exclusive for tryptophan is highlighted in orange. The T-box sequence is displayed in green. Stem I, stem II, stem IIA/B and stem III are indicated. Binding of uncharged tRNA to the specifier sequence as well as the T-box sequence results in stabilization of the antiterminator conformation leading to transcription of the downstream gene (upper structure). Binding of charged cognate tRNA to the specifier sequence results in the formation of the terminator secondary structure and terminates transcription (lower structure; 3′ region). Asterisks indicate nucleotides that are involved in both, mutually exclusive structures, the antiterminator and the terminator. (b) Quantification of trpX mRNA expression under tryptophan-limited conditions from n ≥ 3 experiments. Individual data points and summary measurements (mean ± SD) are plotted in the left panel; effect size (mean differences, black dot) with bootstrapped 95% confidence intervals and resampling distribution are shown in the right panel.
