Fig. 1.

Overall structures of viomycin-containing complexes. (A) Cryo-EM structure of the E. coli 70S ribosome in a complex with viomycin, mRNA, and a single P/E tRNA (red) in the hybrid state. The positions of the five bound viomycin molecules are indicated. (B and C) X-ray crystal structure of a viomycin-containing complex of the E. coli 70S ribosome bound with release factor RF3 (yellow), showing the positions of the five viomycin molecules and their surroundings in the ribosome, including 16S rRNA (cyan), 23S rRNA (gray), and ribosomal protein S12 (blue). (D) The 30S subunit in the cryo-EM structure shown in A (cyan) has undergone an 8.6° counterclockwise rotation relative to its orientation in the classical-state ribosome containing a single bound viomycin (pink) (21).