Influence of recA mutations on gyrA dependent quinolone resistance.
We examined, in Escherichia coli, the influence of recA mutant alleles on the level of quinolone resistance promoted by mutations in the gyrA gene. We found that the recA142 mutation, abolishing all the activities of RecA protein, greatly reduced the level of resistance to the quinolone ciprofloxacin, whereas the recA430 allele affecting the SOS inducing ability of RecA, reduced ciprofloxacin resistance to a lesser extent. The recA142 mutation did not cause enhancement of ciprofloxacin induced DNA breakage in gyrA mutants, indicating that the stabilization of DNA-gyrase complexes by the quinolone is not influenced by a RecA mutant protein. We suggest that RecA protein plays a role in the repair of quinolone damage, principally through a recombinational mechanism and, to a lesser degree, through the induction of the SOS response.
Urios
A
A
Instituto de Investigaciones Citológicas de la Caja de Ahorros de Valencia, Spain.
Herrera
G
G
Aleixandre
V
V
Blanco
M
M
D004260:DNA Repair; D004250:DNA Topoisomerases, Type II / Q000235:genetics*; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D005798:Genes, Bacterial / Q000187:drug effects*; D009154:Mutation; D015363:Quinolones / Q000494:pharmacology*; D011938:Rec A Recombinases / Q000235:genetics*; D013014:SOS Response, Genetics
D015363:Quinolones; D011938:Rec A Recombinases; D004250:DNA Topoisomerases, Type II