title: Cloning and nucleotide sequence of the gyrA gene from Campylobacter fetus subsp. fetus ATCC 27374 and characterization of ciprofloxacin-resistant laboratory and clinical isolates.
abstract: The gyrA gene of Campylobacter fetus subsp. fetus, which encodes the A subunit of DNA gyrase, was cloned, and its nucleotide sequence was determined. An open reading frame of 2,586 nucleotides which encodes a polypeptide of 862 amino acids with an Mr of 96,782 was identified. C. fetus subsp. fetus GyrA is most closely related to Campylobacter jejuni GyrA, with 73% homology at the nucleotide level and 78% identity between polypeptides. The next most closely related GyrA was that from Helicobacter pylori, with both DNA homology and amino acid identity of 63%. The gyrA and gyrB (DNA gyrase B subunit) genes were located on the genomic map of C. fetus subsp. fetus ATCC 27374 and shown to be separate. A clinical isolate of C. fetus subsp. fetus and a laboratory-derived mutant of ATCC 27374, both resistant to ciprofloxacin, had identical mutations within the quinolone resistance determining region. In both mutants a G-->T transversion, corresponding to a substitution of Asp-91 to Tyr in GyrA, was linked to ciprofloxacin resistance, giving MICs of 8 to 16 micrograms/ml.
authors.affiliation: Department of Medical Microbiology & Immunology, University of Alberta, Edmonton, Canada. diane.taylor@ualberta.ca
authors.forename: D E
authors.initials: DE
authors.lastname: Taylor
authors.forename: A S
authors.initials: AS
authors.lastname: Chau
mesh_terms: D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001483:Base Sequence; D002169:Campylobacter Infections / Q000382:microbiology; D002168:Campylobacter fetus / Q000201:enzymology / Q000235:genetics*; D002874:Chromosome Mapping; D002939:Ciprofloxacin / Q000494:pharmacology*; D003001:Cloning, Molecular; D004250:DNA Topoisomerases, Type II / Q000235:genetics*; D004352:Drug Resistance, Microbial; D005798:Genes, Bacterial / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D009693:Nucleic Acid Hybridization
chemical_list: D000890:Anti-Infective Agents; D002939:Ciprofloxacin; D004250:DNA Topoisomerases, Type II