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  • Title: Regulation of DNA supercoiling in Escherichia coli: genetic basis of a compensatory mutation in DNA gyrase.
    Author: McEachern F, Fisher LM.
    Journal: FEBS Lett; 1989 Aug 14; 253(1-2):67-70. PubMed ID: 2547660.
    Abstract:
    Bacterial DNA supercoiling is controlled by balancing the supercoiling activity of DNA gyrase and the relaxing activity of DNA topoisomerase I. We have characterized the gyrB gene from a top A deletion mutant of Escherichia coli (DM800) that has a compensatory mutation in gyrB, lowering the activity of gyrase 10-fold, and thereby redressing the intracellular level of supercoiling. The mutant gene differs from the wild type in carrying three rather than two direct tandem repeats of a 6 bp sequence encoding Ala-Arg. We suggest this novel mutation affects domain spacing and was generated by an unequal crossing over event, possibly involving gyrase.
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