Mutation at the "exit gate" of the salmonella gyrase a subunit suppresses a defect in the gyrase B subunit.
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.
Blanc-Potard
Anne-Béatrice
AB
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
Labesse
Gilles
G
Figueroa-Bossi
Nara
N
Bossi
Lionello
L
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*
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D004278:DNA, Superhelical; D009675:Novobiocin; D027081:DNA Gyrase