Riboswitch-controlled maturation of tRNAPyl in E. coli TOP10 cells. (A) Northern blot analysis and (B) quantitation of tRNAPyl hybridization signals normalized to the signal of the endogenous 5S rRNA. As positive control served le-tRNAPyl, a fusion of tRNAPyl with the last 11 nt at of the 5′-end of RP-RS C. The additional band above the precursor signal (only clearly visible for the positive control le-tRNAPyl and RP-RS A-P) likely represents a complex of processed, uncharged tRNA supF and protein RelA (Ender et al. 2021). In the calculated response ratios (B), RP-RS A-P showed a threefold theophylline-induced activation. For RP-RS C-P, the activation ratio was 13.8-fold. This increase is the result of a very low background cleavage in the absence of theophylline. Data are mean ± SD, n = 3.
