Molecular basis of ribosome recognition and mRNA hydrolysis by the E. coli YafQ toxin

摘要: Bacterial type II toxin-antitoxin modules are protein-protein complexes whose functions finely tuned by rapidly changing environmental conditions. E. coli toxin YafQ is suppressed under steady state growth conditions virtue of its interaction with cognate antitoxin, DinJ. During stress, DinJ proteolytically degraded and free halts translation degrading ribosome-bound mRNA to slow until the stress has passed. Although structures ribosome toxins RelE YoeB have been solved, it unclear what residues among ribosome-dependent essential for mediating both recognition substrate given their low sequence identities. Here we show that coordinates binding 70S via three surface-exposed patches basic propose directly interact 16S rRNA. We demonstrate H50, H63, D67 H87 participate in acid-base catalysis during hydrolysis further H50 H63 functionally complement as general bases initiate phosphodiester cleavage reaction. Moreover residue F91 likely plays an important role positioning. In summary, our findings plasticity active site understanding which function.