title: Suppression of gyrase-mediated resistance by C7 aryl fluoroquinolones.
abstract: Fluoroquinolones form drug-topoisomerase-DNA complexes that rapidly block transcription and replication. Crystallographic and biochemical studies show that quinolone binding involves a water/metal-ion bridge between the quinolone C3-C4 keto-acid and amino acids in helix-4 of the target proteins, GyrA (gyrase) and ParC (topoisomerase IV). A recent cross-linking study revealed a second drug-binding mode in which the other end of the quinolone, the C7 ring system, interacts with GyrA. We report that addition of a dinitrophenyl (DNP) moiety to the C7 end of ciprofloxacin (Cip-DNP) reduced protection due to resistance substitutions in Escherichia coli GyrA helix-4, consistent with the existence of a second drug-binding mode not evident in X-ray structures of drug-topoisomerase-DNA complexes. Several other C7 aryl fluoroquinolones behaved in a similar manner with particular GyrA mutants. Treatment of E. coli cultures with Cip-DNP selectively enriched an uncommon variant, GyrA-A119E, a change that may impede binding of the dinitrophenyl group at or near the GyrA-GyrA interface. Collectively the data support the existence of a secondary quinolone-binding mode in which the quinolone C7 ring system interacts with GyrA; the data also identify C7 aryl derivatives as a new way to obtain fluoroquinolones that overcome existing GyrA-mediated quinolone resistance.
authors.affiliation: Public Heath Research Institute, New Jersey Medical School, Rutgers Biomedical and Health Science, 225 Warren Street, Newark, NJ 07103, USA.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Malik
authors.affiliation: Public Heath Research Institute, New Jersey Medical School, Rutgers Biomedical and Health Science, 225 Warren Street, Newark, NJ 07103, USA.
authors.forename: Arkady
authors.initials: A
authors.lastname: Mustaev
authors.affiliation: University of Iowa, Division of Medicinal & Natural Products Chemistry, College of Pharmacy, Iowa City, IA 52246, USA.
authors.forename: Heidi A
authors.initials: HA
authors.lastname: Schwanz
authors.affiliation: Public Heath Research Institute, New Jersey Medical School, Rutgers Biomedical and Health Science, 225 Warren Street, Newark, NJ 07103, USA.
authors.forename: Gan
authors.initials: G
authors.lastname: Luan
authors.affiliation: Public Heath Research Institute, New Jersey Medical School, Rutgers Biomedical and Health Science, 225 Warren Street, Newark, NJ 07103, USA.
authors.forename: Nirali
authors.initials: N
authors.lastname: Shah
authors.affiliation: Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Oppegard
authors.affiliation: University of Iowa, Division of Medicinal & Natural Products Chemistry, College of Pharmacy, Iowa City, IA 52246, USA.
authors.forename: Ernane C
authors.initials: EC
authors.lastname: de Souza
authors.affiliation: Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hiasa
authors.affiliation: Public Heath Research Institute, New Jersey Medical School, Rutgers Biomedical and Health Science, 225 Warren Street, Newark, NJ 07103, USA Department of Microbiology, Biochemistry & Molecular Genetics, New Jersey Medical School, Rutgers Biomedical and Health Science, 225 Warren Street, Newark, NJ 07103, USA State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, South Xiang-An Road, Xiang-An District, Xiamen, Fujian Province 361102, China.
authors.forename: Xilin
authors.initials: X
authors.lastname: Zhao
authors.affiliation: University of Iowa, Division of Medicinal & Natural Products Chemistry, College of Pharmacy, Iowa City, IA 52246, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Kerns
authors.affiliation: Public Heath Research Institute, New Jersey Medical School, Rutgers Biomedical and Health Science, 225 Warren Street, Newark, NJ 07103, USA Department of Microbiology, Biochemistry & Molecular Genetics, New Jersey Medical School, Rutgers Biomedical and Health Science, 225 Warren Street, Newark, NJ 07103, USA drlicaka@njms.rutgers.edu.
authors.forename: Karl
authors.initials: K
authors.lastname: Drlica
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D027081:DNA Gyrase / Q000737:chemistry / Q000235:genetics*; D004140:Dinitrophenols / Q000737:chemistry; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology; D024841:Fluoroquinolones / Q000737:chemistry* / Q000494:pharmacology; D009154:Mutation; D059005:Topoisomerase II Inhibitors / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D004140:Dinitrophenols; D024841:Fluoroquinolones; D059005:Topoisomerase II Inhibitors; D027081:DNA Gyrase