title: Fluoroquinolone interactions with Mycobacterium tuberculosis gyrase: Enhancing drug activity against wild-type and resistant gyrase.
abstract: Mycobacterium tuberculosis is a significant source of global morbidity and mortality. Moxifloxacin and other fluoroquinolones are important therapeutic agents for the treatment of tuberculosis, particularly multidrug-resistant infections. To guide the development of new quinolone-based agents, it is critical to understand the basis of drug action against M. tuberculosis gyrase and how mutations in the enzyme cause resistance. Therefore, we characterized interactions of fluoroquinolones and related drugs with WT gyrase and enzymes carrying mutations at GyrA(A90) and GyrA(D94). M. tuberculosis gyrase lacks a conserved serine that anchors a water-metal ion bridge that is critical for quinolone interactions with other bacterial type II topoisomerases. Despite the fact that the serine is replaced by an alanine (i.e., GyrA(A90)) in M. tuberculosis gyrase, the bridge still forms and plays a functional role in mediating quinolone-gyrase interactions. Clinically relevant mutations at GyrA(A90) and GyrA(D94) cause quinolone resistance by disrupting the bridge-enzyme interaction, thereby decreasing drug affinity. Fluoroquinolone activity against WT and resistant enzymes is enhanced by the introduction of specific groups at the C7 and C8 positions. By dissecting fluoroquinolone-enzyme interactions, we determined that an 8-methyl-moxifloxacin derivative induces high levels of stable cleavage complexes with WT gyrase and two common resistant enzymes, GyrA(A90V) and GyrA(D94G). 8-Methyl-moxifloxacin was more potent than moxifloxacin against WT M. tuberculosis gyrase and displayed higher activity against the mutant enzymes than moxifloxacin did against WT gyrase. This chemical biology approach to defining drug-enzyme interactions has the potential to identify novel drugs with improved activity against tuberculosis.
authors.affiliation: Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146;
authors.forename: Katie J
authors.initials: KJ
authors.lastname: Aldred
authors.affiliation: Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2185;
authors.forename: Tim R
authors.identifier: http://orcid.org/0000-0002-7390-6458
authors.initials: TR
authors.lastname: Blower
authors.affiliation: Division of Medicinal and Natural Products Chemistry, University of Iowa College of Pharmacy, Iowa City, IA 52242;
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Kerns
authors.affiliation: Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2185; jmberger@jhmi.edu neil.osheroff@vanderbilt.edu.
authors.forename: James M
authors.initials: JM
authors.lastname: Berger
authors.affiliation: Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146; Department of Medicine (Hematology/Oncology), Vanderbilt University School of Medicine, Nashville, TN 37232-2358; VA Tennessee Valley Healthcare System, Nashville, TN 37212 jmberger@jhmi.edu neil.osheroff@vanderbilt.edu.
authors.forename: Neil
authors.initials: N
authors.lastname: Osheroff
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology*; D027081:DNA Gyrase / Q000187:drug effects* / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D024841:Fluoroquinolones / Q000494:pharmacology*; D008670:Metals / Q000737:chemistry; D000077266:Moxifloxacin; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000201:enzymology; D014867:Water / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D008670:Metals; D014867:Water; D002939:Ciprofloxacin; D027081:DNA Gyrase; D000077266:Moxifloxacin
keywords: Mycobacterium tuberculosis; antibiotic resistance; complex stability; fluoroquinolones; gyrase