ErmE superpositioned onto TFB1M bound to rRNA suggests ErmE regions in contact with rRNA. (A) A superposition of ErmE (pdb code 6nvm) onto the structure of TFB1M bound to its RNA substrate is shown. A high degree of structural similarity is observed between ErmE and TFB1M, particularly in the Rossman-fold (RF) catalytic domain. The carboxy-terminal domain (CTD) varies between the two structures. Helices α4, α5, and α6 are poised to play a central role in RNA binding. (B) A detailed view of the ErmE–TFB1M superposition reveals that a key aromatic residue (TFB1M F144, ErmE Y134) and a basic residue (TFB1M R183, ErmE K164) are positioned in the same vicinity between the two structures but must undergo a conformational change for ErmE to bind RNA as in the TFB1M–RNA crystal structure.
