Fig. 6: Cryo-EM Structure of THB-bound 70S•mRNA•fMet-tRNAfMet complex.
a Cryo-EM structure of THB-bound E. coli 70S IC carrying XR7 mRNA and fMet-tRNAfMet. THB (blue) intercalates between the bases of h44 in the 16S rRNA (green) and H69 of the 23S rRNA (orange) of the mRNA (yellow) bound 70S ribosome. The fMet-tRNAfMet (saddle brown) is stably bound to the P site. b EM-density of THB at the binding pocket fitted with the model. c Close look at the decoding center reveals interactions of the bound THB with rRNA bases of H69 of 23S rRNA (orange) and h44 of 16 S rRNA (green). Rearrangement of the nucleobases A1913 and C1914 from H69 and A1492 and A1493 from h44 are shown. Dotted lines in black represent hydrogen bonds. d THB-induced displacement of C1914 clashes with the accommodated aa-tRNA in the A site as seen from superposition of our 70S-THB structure and aa-tRNA bound 70S ribosome, PDB 7K0030. e Extensive clashes of extruded base C1914 with multiple amino acid residues (E114, V115, and R116) in the domain II of RF1 from superposition of 70S-THB structure with RF1 bound pre-termination ribosome, PDB 6DNC47. f THB-induced structural changes at the A site show no sterical clashes with RRF as observed by superposition of 70S-THB structure with RRF bound post-termination ribosome, PDB 4V5448.
