title: Selective protein synthesis by ribosomes with a drug-obstructed exit tunnel.
abstract: The polypeptide exit tunnel is an important functional compartment of the ribosome where the newly synthesized proteins are surveyed. The tunnel is the target of clinically important macrolide antibiotics. Macrolides plug the tunnel and are believed to stop production of all proteins. Contrary to this view, we show that drug-bound ribosomes can synthesize a distinct subset of cellular polypeptides. The structure of a protein defines its ability to thread through the antibiotic-obstructed tunnel. Synthesis of certain polypeptides that initially bypass translational arrest can be stopped at later stages of elongation while translation of some proteins goes to completion. Our findings reveal that small-molecule effectors can accentuate the discriminatory properties of the ribosomal exit tunnel and that macrolide antibiotics reshape the cellular proteome rather than block global protein synthesis.
authors.affiliation: Center for Pharmaceutical Biotechnology, University of Illinois at Chicago, 900 S. Ashland Avenue, Chicago, IL 60607, USA.
authors.forename: Krishna
authors.initials: K
authors.lastname: Kannan
authors.forename: Nora
authors.initials: N
authors.lastname: Vázquez-Laslop
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Mankin
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism*; D018942:Macrolides / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010441:Peptide Chain Elongation, Translational; D014176:Protein Biosynthesis / Q000187:drug effects*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D012270:Ribosomes / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D018942:Macrolides; D011500:Protein Synthesis Inhibitors