title: An Escherichia coli DNA topoisomerase I mutant has a compensatory mutation that alters two residues between functional domains of the DNA gyrase A protein.
abstract: Nucleotide sequence analysis revealed that the compensatory gyrA mutation in Escherichia coli DM750 affects DNA supercoiling by interchanging the identities of Ala-569 and Thr-586 in the DNA gyrase A subunit. These residues flank Arg-571, a site for trypsin cleavage that splits gyrase A protein between DNA breakage-reunion and DNA-binding domains. The putative interdomain locations of the DM750 mutation and that of E. coli DM800 (in gyrase B protein) suggests that these compensatory mutations may reduce DNA supercoiling activity by altering allosteric interactions in the gyrase complex.
authors.affiliation: Department of Cellular and Molecular Sciences, St. George's Hospital Medical School, University of London, United Kingdom.
authors.forename: M
authors.initials: M
authors.lastname: Oram
authors.forename: L M
authors.initials: LM
authors.lastname: Fisher
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004264:DNA Topoisomerases, Type I / Q000737:chemistry / Q000235:genetics*; D004250:DNA Topoisomerases, Type II / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004278:DNA, Superhelical / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009838:Oligodeoxyribonucleotides / Q000235:genetics; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping
chemical_list: D004278:DNA, Superhelical; D009838:Oligodeoxyribonucleotides; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II