title: Mutation at the "exit gate" of the salmonella gyrase a subunit suppresses a defect in the gyrase B subunit.
abstract: In Salmonella enterica serovar Typhimurium, an S431P substitution in the B subunit of gyrase (allele gyrB651) confers resistance to nalidixic acid and causes reduced DNA superhelicity and hypersensitivity to novobiocin. Selection for novobiocin resistance allowed isolation of a mutation in the gyrA gene (allele gyrA659), a T467S substitution, which partially suppresses the supercoiling defect of gyrB651. Modeling analysis suggests that this mutation acts by destabilizing the GyrA bottom dimer interface. This is the first example of a gyrA mutation that compensates for a gyrB defect.
authors.affiliation: Avenir team Institut National de la Santé et de la Recherche Médicale, Unité 431, Faculté de Médecine, CS 83021, Avenue J. F. Kennedy, 30908 Nîmes Cedex 02, France. ablancpotard@univ-montp1.fr
authors.forename: Anne-Béatrice
authors.initials: AB
authors.lastname: Blanc-Potard
authors.forename: Gilles
authors.initials: G
authors.lastname: Labesse
authors.forename: Nara
authors.initials: N
authors.lastname: Figueroa-Bossi
authors.forename: Lionello
authors.initials: L
authors.lastname: Bossi
mesh_terms: D000483:Alleles; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D027081:DNA Gyrase / Q000737:chemistry / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D004278:DNA, Superhelical / Q000235:genetics; D019281:Dimerization; D009675:Novobiocin / Q000494:pharmacology; D010641:Phenotype; D017354:Point Mutation; D012486:Salmonella typhimurium / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004278:DNA, Superhelical; D009675:Novobiocin; D027081:DNA Gyrase