Fig. 2.

Effect of U1052G mutation on tRNA selection in the presence of negamycin and tetracycline. (A) The overlapping binding sites of negamycin and tetracycline on the small subunit A site. Negamycin and tetracycline are shown in blue and green, respectively. (B) Chemical structures of (Upper) negamycin and (Lower) tetracycline. The ring nomenclature is indicated. (C) In vitro-coupled transcription–translation activity of wild-type (blue; IC₅₀ value of 15 µM) and U1052G (green; IC₅₀ value of 2.7 µM) ribosomes in the presence of tetracycline. (D) smFRET imaging of aa-tRNA selection. Real-time delivery of ternary complex to wild-type and U1052G ribosomes in the presence of increasing concentrations of tetracycline. Fraction occupancy refers to the GA (intermediate FRET; blue and green squares) and the accommodated (high-FRET; black circles) states for all molecules.