title: Dissecting the ribosomal inhibition mechanisms of edeine and pactamycin: the universally conserved residues G693 and C795 regulate P-site RNA binding.
abstract: The crystal structures of the universal translation-initiation inhibitors edeine and pactamycin bound to ribosomal 30S subunit have revealed that edeine induces base pairing of G693:C795, residues that constitute the pactamycin binding site. Here, we show that base pair formation by addition of edeine inhibits tRNA binding to the P site by preventing codon-anticodon interaction and that addition of pactamycin, which rebreaks the base pair, can relieve this inhibition. In addition, edeine induces translational misreading in the A site, at levels comparable to those induced by the classic misreading antibiotic streptomycin. Binding of pactamycin between residues G693 and C795 strongly inhibits translocation with a surprising tRNA specificity but has no effect on translation initiation, suggesting that reclassification of this antibiotic is necessary. Collectively, these results suggest that the universally conserved G693:C795 residues regulate tRNA binding at the P site of the ribosome and influence translocation efficiency.
authors.affiliation: Department of Biochemistry, School of Medicine, University of Patras, 26500 Patras, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Dinos
authors.forename: Daniel N
authors.initials: DN
authors.lastname: Wilson
authors.forename: Yoshika
authors.initials: Y
authors.lastname: Teraoka
authors.forename: Witold
authors.initials: W
authors.lastname: Szaflarski
authors.forename: Paola
authors.initials: P
authors.lastname: Fucini
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Kalpaxis
authors.forename: Knud H
authors.initials: KH
authors.lastname: Nierhaus
mesh_terms: D000926:Anticodon / Q000378:metabolism; D020029:Base Pairing; D001665:Binding Sites; D003062:Codon / Q000378:metabolism; D003596:Cytosine / Q000378:metabolism*; D004486:Edeine / Q000494:pharmacology*; D004926:Escherichia coli; D049452:Green Fluorescent Proteins; D006147:Guanine / Q000378:metabolism*; D008164:Luminescent Proteins / Q000378:metabolism; D008954:Models, Biological; D008958:Models, Molecular; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010142:Pactamycin / Q000494:pharmacology*; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012313:RNA / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000926:Anticodon; D003062:Codon; D008164:Luminescent Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D011500:Protein Synthesis Inhibitors; D012335:RNA, Ribosomal; D012269:Ribosomal Proteins; D004486:Edeine; D049452:Green Fluorescent Proteins; D010142:Pactamycin; D006147:Guanine; D012313:RNA; D003596:Cytosine; D012343:RNA, Transfer