Inhibition of transfer messenger RNA aminoacylation and trans-translation by aminoglycoside antibiotics.
Transfer messenger RNA (tmRNA) directs the modification of proteins of which the biosynthesis has stalled or has been interrupted. Here, we report that aminoglycosides can interfere with this quality control system in bacteria, termed trans-translation. Neomycin B is the strongest inhibitor of tmRNA aminoacylation with alanine (K(i) value of approximately 35 micro m), an essential step during trans-translation. The binding sites of neomycin B do not overlap with the identity determinants for alanylation, but the aminoglycoside perturbs the conformation of the acceptor stem that contains the aminoacylation signals. Aminoglycosides reduce the conformational freedom of the transfer RNA-like domain of tmRNA. Additional contacts between aminoglycosides and tmRNA are within the tag reading frame, probably also disturbing reprogramming of the stalled ribosomes prior protein tagging. Aminoglycosides impair tmRNA aminoacylation in the presence of all of the transfer RNAs from Escherichia coli, small protein B, and elongation factor Tu, but when both proteins are present, the inhibition constant is 1 order of magnitude higher. SmpB and elongation factor Tu have RNA chaperone activities, ensuring that tmRNA adopts an optimal conformation during aminoacylation.
Corvaisier
Sophie
S
Laboratoire de Biochimie Pharmaceutique, Faculté de Pharmacie, Université de Rennes I, UPRES Jeune Equipe 2311, 2 avenue du Professeur Léon Bernard, 35043 Rennes, France.
Bordeau
Valérie
V
Felden
Brice
B
D000215:Acylation / Q000187:drug effects; D000409:Alanine / Q000378:metabolism; D000412:Alanine-tRNA Ligase / Q000378:metabolism; D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004926:Escherichia coli / Q000235:genetics; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009690:Nucleic Acid Conformation / Q000187:drug effects; D014176:Protein Biosynthesis / Q000187:drug effects*; D012329:RNA, Bacterial / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D012344:RNA, Transfer, Ala / Q000378:metabolism
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D012329:RNA, Bacterial; D012344:RNA, Transfer, Ala; C096222:tmRNA; D000412:Alanine-tRNA Ligase; D008274:Magnesium; D000409:Alanine