title: Quinolone-resistant mutations of the gyrA gene of Escherichia coli.
abstract: DNA fragments of 8.5 kb containing the gyrA gene were cloned from Escherichia coli KL-16 and from four spontaneous gyrA mutants which showed various levels of resistance to quinolones. The gyrA gene was situated at about 4 kb in front of the nrdA gene and transcribed counterclockwise on the E. coli chromosome. It encoded a polypeptide of 875 amino acids with a molecular weight of about 97,000. The four gyrA mutations were located strikingly close to one another within a small region near the N-terminus of the gyrA polypeptide, i.e., nucleotide changes from C to T, from C to G, from G to T and from G to T at nucleotides 248, 248, 318 and 199, respectively, resulting in amino acid changes from Ser to Leu, from Ser to Trp, from Gln to His and from Ala to Ser at amino acids 83, 83, 106 and 67, respectively. These mutations were situated in the relatively hydrophilic regions of the GyrA polypeptide and close to Tyr at amino acid 122 which has been shown to be the site covalently bound to DNA.
authors.affiliation: Research Laboratories, Dainippon Pharmaceutical Co. Ltd., Osaka, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Yoshida
authors.forename: T
authors.initials: T
authors.lastname: Kojima
authors.forename: J
authors.initials: J
authors.lastname: Yamagishi
authors.forename: S
authors.initials: S
authors.lastname: Nakamura
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents; D001412:Bacillus subtilis / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D004250:DNA Topoisomerases, Type II / Q000235:genetics*; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000235:genetics*; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D011804:Quinolines / Q000494:pharmacology*; D012995:Solubility; D059005:Topoisomerase II Inhibitors
chemical_list: D000900:Anti-Bacterial Agents; D011804:Quinolines; D059005:Topoisomerase II Inhibitors; D004250:DNA Topoisomerases, Type II