title: Escherichia coli DNA gyrase: genetic analysis of gyrA and gyrB mutations responsible for thermosensitive enzyme activity.
abstract: Escherichia coli gyrA43 and gyrB203 alleles conferring temperature-sensitive (ts) growth encoded Gly751-->Asp and Pro171-->Ser substitutions in the DNA gyrase A and B subunits, respectively. A plasmid-borne gyrA43 allele was genetically dominant over a chromosomal quinolone-resistant gyrA gene at 30 degrees C but not at 42 degrees C. These results and others confirm the ts phenotype of the mutation, the first to be identified in the C-terminal DNA binding/complex stabilizing domain of gyrase A protein. By contrast, the Pro171-->Ser mutation is located near the ATP-binding site of gyrase B protein and could interfere with energy coupling during DNA supercoiling. These data are discussed in regard to recently described gyrA(ts) mutations that affect the control of chromosome segregation.
authors.affiliation: Department of Cellular and Molecular Sciences, St. George's Hospital Medical School, University of London, UK.
authors.forename: M
authors.initials: M
authors.lastname: Oram
authors.forename: R
authors.initials: R
authors.lastname: Kuroda
authors.forename: L M
authors.initials: LM
authors.lastname: Fisher
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D004250:DNA Topoisomerases, Type II / Q000235:genetics* / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D005798:Genes, Bacterial; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009154:Mutation; D009838:Oligodeoxyribonucleotides; D016133:Polymerase Chain Reaction / Q000379:methods; D013696:Temperature
chemical_list: D004269:DNA, Bacterial; D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D004250:DNA Topoisomerases, Type II