Paraquat-mediated selection for mutations in the manganese-superoxide dismutase gene sodA.
We report the unexpected result that Escherichia coli isolates containing a multicopy plasmid (pDT1.5) carrying the manganese-superoxide dismutase gene sodA were more sensitive than the wild type to paraquat-mediated growth inhibition. The pDT1.5 locus responsible for the paraquat-sensitive phenotype was delimited to a 0.6-kilobase segment by transposon Tn5 mutagenesis. Moreover, superoxide dismutase activity was the same as in the wild type in strains carrying pDT1.5::Tn5 insertions mapping to the 0.6-kilobase locus. These data identify the 0.6-kilobase segment as the locus of sodA and establish an association between growth inhibition by paraquat and the function of the plasmid-borne sodA gene.
D004251:DNA Transposable Elements; D004274:DNA, Recombinant; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D005796:Genes; D005798:Genes, Bacterial; D009154:Mutation; D010269:Paraquat / Q000494:pharmacology*; D010957:Plasmids; D013482:Superoxide Dismutase / Q000235:genetics*
D004251:DNA Transposable Elements; D004274:DNA, Recombinant; D013482:Superoxide Dismutase; D010269:Paraquat