title: Molecular mechanism of viomycin inhibition of peptide elongation in bacteria.
abstract: Viomycin is a tuberactinomycin antibiotic essential for treating multidrug-resistant tuberculosis. It inhibits bacterial protein synthesis by blocking elongation factor G (EF-G) catalyzed translocation of messenger RNA on the ribosome. Here we have clarified the molecular aspects of viomycin inhibition of the elongating ribosome using pre-steady-state kinetics. We found that the probability of ribosome inhibition by viomycin depends on competition between viomycin and EF-G for binding to the pretranslocation ribosome, and that stable viomycin binding requires an A-site bound tRNA. Once bound, viomycin stalls the ribosome in a pretranslocation state for a minimum of ∼ 45 s. This stalling time increases linearly with viomycin concentration. Viomycin inhibition also promotes futile cycles of GTP hydrolysis by EF-G. Finally, we have constructed a kinetic model for viomycin inhibition of EF-G catalyzed translocation, allowing for testable predictions of tuberactinomycin action in vivo and facilitating in-depth understanding of resistance development against this important class of antibiotics.
authors.affiliation: Department of Cell and Molecular biology, Uppsala University, 75124 Uppsala, Sweden.
authors.forename: Mikael
authors.initials: M
authors.lastname: Holm
authors.affiliation: Department of Cell and Molecular biology, Uppsala University, 75124 Uppsala, Sweden.
authors.forename: Anneli
authors.initials: A
authors.lastname: Borg
authors.affiliation: Department of Cell and Molecular biology, Uppsala University, 75124 Uppsala, Sweden.
authors.forename: Måns
authors.initials: M
authors.lastname: Ehrenberg
authors.affiliation: Department of Cell and Molecular biology, Uppsala University, 75124 Uppsala, Sweden suparna.sanyal@icm.uu.se.
authors.forename: Suparna
authors.initials: S
authors.lastname: Sanyal
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006160:Guanosine Triphosphate / Q000737:chemistry; D020653:Peptide Elongation Factor G / Q000037:antagonists & inhibitors*; D011336:Probability; D014176:Protein Biosynthesis / Q000187:drug effects*; D012270:Ribosomes / Q000187:drug effects / Q000378:metabolism; D014756:Viomycin / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D020653:Peptide Elongation Factor G; D006160:Guanosine Triphosphate; D014756:Viomycin
keywords: antibiotics; protein synthesis; ribosome; tuberculosis; viomycin