Fig. 4.
Interaction between EF-Tu and the T-stem base pairs of aa-tRNA in ternary complex before and after GTP hydrolysis on the ribosome. (A) Overlay of EF-Tu·GDP [green, Protein Data Bank (PDB) 1tui (35)] based on domains II and III onto EF-Tu·GDPCP (orange) in complex with Trp-tRNATrp G24A (blue) bound to the 70S ribosome from Thermus thermophilus [PDB 4v5l (36)]. The tRNA base pairs 51 to 63, 52 to 62, and 53 to 61 in the T stem are highlighted in hot pink. Domains II and III of EF-Tu·GDP superpose onto the same domains from EF-Tu·GDPCP with a root-mean-square deviation of 0.79 Å over 189 Cα atoms. (B) The complex of EF-Tu·GDP with aminoacyl-tRNA is sterically compatible with ribosome binding; 30S is shown in light yellow, and 50S is shown in light blue. The conformational change upon GTP hydrolysis is indicated by an arrow. Superpositioning was done using the LSQ commands in O (37). The images were prepared using Pymol version 1.8 (Schrödinger, LLC).