title: Context-specific inhibition of translation by ribosomal antibiotics targeting the peptidyl transferase center.
abstract: The first broad-spectrum antibiotic chloramphenicol and one of the newest clinically important antibacterials, linezolid, inhibit protein synthesis by targeting the peptidyl transferase center of the bacterial ribosome. Because antibiotic binding should prevent the placement of aminoacyl-tRNA in the catalytic site, it is commonly assumed that these drugs are universal inhibitors of peptidyl transfer and should readily block the formation of every peptide bond. However, our in vitro experiments showed that chloramphenicol and linezolid stall ribosomes at specific mRNA locations. Treatment of bacterial cells with high concentrations of these antibiotics leads to preferential arrest of translation at defined sites, resulting in redistribution of the ribosomes on mRNA. Antibiotic-mediated inhibition of protein synthesis is most efficient when the nascent peptide in the ribosome carries an alanine residue and, to a lesser extent, serine or threonine in its penultimate position. In contrast, the inhibitory action of the drugs is counteracted by glycine when it is either at the nascent-chain C terminus or at the incoming aminoacyl-tRNA. The context-specific action of chloramphenicol illuminates the operation of the mechanism of inducible resistance that relies on programmed drug-induced translation arrest. In addition, our findings expose the functional interplay between the nascent chain and the peptidyl transferase center.
authors: Center for Biomolecular Sciences, University of Illinois, Chicago, IL 60607.
authors: James
authors: J
authors: Marks
authors: Center for Biomolecular Sciences, University of Illinois, Chicago, IL 60607.
authors: Krishna
authors: K
authors: Kannan
authors: Center for Biomolecular Sciences, University of Illinois, Chicago, IL 60607.
authors: Emily J
authors: EJ
authors: Roncase
authors: Center for Biomolecular Sciences, University of Illinois, Chicago, IL 60607.
authors: Dorota
authors: D
authors: Klepacki
authors: Center for Biomolecular Sciences, University of Illinois, Chicago, IL 60607.
authors: Amira
authors: A
authors: Kefi
authors: Center for Biomolecular Sciences, University of Illinois, Chicago, IL 60607.
authors: Cédric
authors: C
authors: Orelle
authors: Center for Biomolecular Sciences, University of Illinois, Chicago, IL 60607 shura@uic.edu nvazquez@uic.edu.
authors: Nora
authors: N
authors: Vázquez-Laslop
authors: Center for Biomolecular Sciences, University of Illinois, Chicago, IL 60607 shura@uic.edu nvazquez@uic.edu.
authors: Alexander S
authors: AS
authors: Mankin
mesh_terms: D000596:Amino Acids / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D002701:Chloramphenicol / Q000737:chemistry / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D000069349:Linezolid / Q000737:chemistry / Q000494:pharmacology*; D008958:Models, Molecular; D010458:Peptidyl Transferases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism
chemical_list: D000596:Amino Acids; D012333:RNA, Messenger; D012346:RNA, Transfer, Amino Acyl; D002701:Chloramphenicol; D010458:Peptidyl Transferases; D000069349:Linezolid
keywords: antibiotics; nascent peptide; oxazolidinones; protein synthesis; ribosome