title: Oxazolidinones mechanism of action: inhibition of the first peptide bond formation.
abstract: Oxazolidinones are potent inhibitors of bacterial protein biosynthesis. Previous studies have demonstrated that this new class of antimicrobial agent blocks translation by inhibiting initiation complex formation, while post-initiation translation by polysomes and poly(U)-dependent translation is not a target for these compounds. We found that oxazolidinones inhibit translation of natural mRNA templates but have no significant effect on poly(A)-dependent translation. Here we show that various oxazolidinones inhibit ribosomal peptidyltransferase activity in the simple reaction of 70 S ribosomes using initiator-tRNA or N-protected CCA-Phe as a P-site substrate and puromycin as an A-site substrate. Steady-state kinetic analysis shows that oxazolidinones display a competitive inhibition pattern with respect to both the P-site and A-site substrates. This is consistent with a rapid equilibrium, ordered mechanism of the peptidyltransferase reaction, wherein binding of the A-site substrate can occur only after complex formation between peptidyltransferase and the P-site substrate. We propose that oxazolidinones inhibit bacterial protein biosynthesis by interfering with the binding of initiator fMet-tRNA(i)(Met) to the ribosomal peptidyltransferase P-site, which is vacant only prior to the formation of the first peptide bond.
authors.affiliation: DuPont Pharmaceuticals Company, Wilmington, Delaware 19880, USA.
authors.forename: U
authors.initials: U
authors.lastname: Patel
authors.forename: Y P
authors.initials: YP
authors.lastname: Yan
authors.forename: F W
authors.initials: FW
authors.lastname: Hobbs
authors.forename: J
authors.initials: J
authors.lastname: Kaczmarczyk
authors.forename: A M
authors.initials: AM
authors.lastname: Slee
authors.forename: D L
authors.initials: DL
authors.lastname: Pompliano
authors.forename: M G
authors.initials: MG
authors.lastname: Kurilla
authors.forename: E V
authors.initials: EV
authors.lastname: Bobkova
mesh_terms: D004347:Drug Interactions; D004926:Escherichia coli / Q000201:enzymology / Q000378:metabolism; D007700:Kinetics; D023303:Oxazolidinones / Q000494:pharmacology*; D010452:Peptide Biosynthesis / Q000187:drug effects; D010458:Peptidyl Transferases / Q000037:antagonists & inhibitors / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D011691:Puromycin / Q000037:antagonists & inhibitors*; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics
chemical_list: D023303:Oxazolidinones; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D011691:Puromycin; D010458:Peptidyl Transferases