Novel quinolone resistance mutations of the Escherichia coli DNA gyrase A protein: enzymatic analysis of the mutant proteins.
Article Details
- CitationCopy to clipboard
Hallett P, Maxwell A
Novel quinolone resistance mutations of the Escherichia coli DNA gyrase A protein: enzymatic analysis of the mutant proteins.
Antimicrob Agents Chemother. 1991 Feb;35(2):335-40.
- PubMed ID
- 1850970 [ View in PubMed]
- Abstract
Using the techniques of gap misrepair mutagenesis and site-directed mutagenesis, we have generated two novel quinolone resistance mutations of the Escherichia coli DNA gyrase A protein. DNA sequencing showed these mutations to be Ser-83----Ala and Gln-106----Arg. The mutant proteins were overproduced and purified, and their enzymatic properties were analyzed and compared with those of the wild-type enzyme. With ciprofloxacin and other quinolones, the inhibition of DNA supercoiling, relaxation, and decatenation and the induction of DNA cleavage were investigated for both wild-type and mutant enzymes. In each assay, the mutant enzymes were found to require approximately 10 times more drug to inhibit the reaction or induce cleavage than was the wild-type enzyme. However, the Ca2(+)-directed DNA cleavage reaction was indistinguishable for wild-type and mutant gyrases. We discuss models for the gyrase-mediated bactericidal effects of quinolone drugs.