title: Dual mechanism of action of the atypical tetracycline chelocardin.
abstract: Classical tetracyclines targeting the protein biosynthesis machinery are commonly applied in human and veterinary medicine. The development and spread of resistance seriously compromise the successful treatment of bacterial infections. The atypical tetracycline chelocardin holds promise as it retains activity against tetracycline-resistant strains. It has been suggested that chelocardin targets the bacterial membrane, thus differing in mode of action from that of classical tetracyclines. We investigated the mechanism of action of chelocardin using global proteome analysis. The proteome profiles after sublethal chelocardin stress were compared to a reference compendium containing antibiotic response profiles of Bacillus subtilis. This approach revealed a concentration-dependent dual mechanism of action. At low concentrations, like classical tetracyclines, chelocardin induces the proteomic signature for peptidyl transferase inhibition demonstrating that protein biosynthesis inhibition is the dominant physiological challenge. At higher concentrations B. subtilis mainly responds to membrane stress indicating that at clinically relevant concentrations the membrane is the main antibiotic target of chelocardin. Studying the effects on the membrane in more detail, we found that chelocardin causes membrane depolarization but does not lead to formation of large pores. We conclude that at growth inhibiting doses chelocardin not only targets protein biosynthesis but also corrupts the integrity of the bacterial membrane. This dual mechanism of action might prove beneficial in slowing the development of new resistance mechanisms against this atypical tetracycline.
authors.affiliation: Ruhr University Bochum, Applied Microbiology, Universitätsstraße 150, 44801 Bochum, Germany.
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Stepanek
authors.affiliation: ACIES BIO, Tehnoloski park 21, 1000 Ljubljana, Slovenia.
authors.forename: Tadeja
authors.initials: T
authors.lastname: Lukežič
authors.affiliation: Ruhr University Bochum, Lehrstuhl für Allgemeine und Molekulare Botanik, Universitätsstraße 150, 44801 Bochum, Germany.
authors.forename: Ines
authors.initials: I
authors.lastname: Teichert
authors.affiliation: ACIES BIO, Tehnoloski park 21, 1000 Ljubljana, Slovenia.
authors.forename: Hrvoje
authors.initials: H
authors.lastname: Petković
authors.affiliation: Ruhr University Bochum, Applied Microbiology, Universitätsstraße 150, 44801 Bochum, Germany. Electronic address: julia.bandow@rub.de.
authors.forename: Julia E
authors.initials: JE
authors.lastname: Bandow
mesh_terms: D001412:Bacillus subtilis / Q000187:drug effects / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D008826:Microbial Sensitivity Tests; D020543:Proteome; D013754:Tetracyclines / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; D020543:Proteome; D013754:Tetracyclines; C000400:chelocardin
keywords: Atypical tetracycline; Chelocardin; Mechanism of action; Membrane stress; Protein biosynthesis inhibition; Proteomic profiling