Context‐specific action of linezolid and chloramphenicol, the inhibitors of ribosomal peptidyl transferase (752.12)

Protein synthesis has been a successful target for antibiotics, with many different inhibitors targeting functional sites of the ribosome. Understanding the mode of antibiotic action is critical for drug development and elucidating the fundamental mechanisms of protein synthesis. Chloramphenicol and linezolid have been shown to bind at the A site in the peptidyl transferase center, and in theory should prevent any peptide bond formation. However, in the cell free translation system, ribosomes in the presence of either antibiotic are not arrested at the initiator codon but instead are able to catalyze the formation of a number of peptide bonds before halting translation. The exact sites of arrest appear to be context dependent, and possibly different for these two antibiotics despite binding to the same ribosomal site. No obvious consensus sequence defining the sites of antibiotic‐induced arrest emerged from analysis of in vitro translation of several selected genes. Therefore, we are expanding these studies using genome‐wide ribosome profiling. This approach should reveal the context of the gene sites at which these inhibitors arrest translation in vivo. We believe our investigation will provide critical insights into mechanism of translation inhibition by chloramphenicol and linezolid and pave the way for future drug design. Importantly, our studies may reveal unknown aspects of catalysis of peptide bond formation by the ribosome. Grant Funding Source : Supported by NIH