title: Accumulation of mutations in both gyrB and parE genes is associated with high-level resistance to novobiocin in Staphylococcus aureus.
abstract: Coumarin-resistant mutants of Staphylococcus aureus were isolated by three-step selection with novobiocin at different concentrations. Sequencing analysis of the gyrB and parE genes of the first-, second-, and third-step mutants revealed that successive point mutations first occurred specifically in the gyrB gene, followed by a point mutation in the parE gene and then an additional point mutation in the gyrB gene. These findings demonstrate that DNA gyrase is the primary target and that topoisomerase IV is the secondary target for novobiocin and that the accumulation of point mutations in both the gyrB and the parE genes is associated with high-level resistance to novobiocin in S. aureus. Moreover, our results show that the amino acid substitutions (Asp-89 to Gly and Ser-128 to Leu) found in GyrB are associated with resistance to novobiocin but not to coumermycin A1, suggesting that the interactions of novobiocin and coumermycin A1 with GyrB differ at the molecular level.
authors.affiliation: Pharmacology & Microbiology Research Laboratories, Dainippon Pharmaceutical Co., Ltd., Enoki 33-94, Suita, Osaka 564-0053, Japan.
authors.forename: Mika
authors.initials: M
authors.lastname: Fujimoto-Nakamura
authors.forename: Hideaki
authors.initials: H
authors.lastname: Ito
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Oyamada
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nishino
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Yamagishi
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003374:Coumarins / Q000494:pharmacology; D027081:DNA Gyrase / Q000235:genetics / Q000378:metabolism*; D027101:DNA Topoisomerase IV / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial; D024841:Fluoroquinolones / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics / Q000502:physiology; D009675:Novobiocin / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D003374:Coumarins; D004269:DNA, Bacterial; D024841:Fluoroquinolones; D009675:Novobiocin; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase; C061363:sparfloxacin