title: Molecular cloning of the gyrA and gyrB genes of Bacteroides fragilis encoding DNA gyrase.
abstract: The genes encoding the DNA gyrase A and B subunits of Bacteroides fragilis were cloned and sequenced. The gyrA and gyrB genes code for proteins of 845 and 653 amino acids, respectively. These proteins were expressed in Escherichia coli, and the combination of GyrA and GyrB exhibited ATP-dependent supercoiling activity. To analyze the role of DNA gyrase in quinolone resistance of B. fragilis, we isolated mutant strains by stepwise selection for resistance to increasing concentrations of levofloxacin. We analyzed the resistant mutants and showed that Ser-82 of GyrA, equivalent to resistance hot spot Ser-83 of GyrA in E. coli, was in each case replaced with Phe. These results suggest that DNA gyrase is an important target for quinolones in B. fragilis.
authors.affiliation: New Product Research Laboratories I, Daiichi Pharmaceutical Co., Ltd., Edogawa-ku, Tokyo 134-8630, Japan. onode90j@daiichipharm.co.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Onodera
authors.forename: K
authors.initials: K
authors.lastname: Sato
mesh_terms: D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000494:pharmacology; D001441:Bacteroides fragilis / Q000187:drug effects / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D027081:DNA Gyrase; D004250:DNA Topoisomerases, Type II / Q000235:genetics* / Q000302:isolation & purification; D004269:DNA, Bacterial / Q000032:analysis; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli; D005798:Genes, Bacterial; D064704:Levofloxacin; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation; D015242:Ofloxacin / Q000494:pharmacology; D011994:Recombinant Proteins / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid
chemical_list: D000890:Anti-Infective Agents; D004269:DNA, Bacterial; D011994:Recombinant Proteins; D064704:Levofloxacin; D015242:Ofloxacin; D027081:DNA Gyrase; D004250:DNA Topoisomerases, Type II