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Regulation of DNA supercoiling in Escherichia coli : Genetic basis of a compensatory mutation in DNA gyrase
Author(s) -
McEachern Fiona,
Fisher L.Mark
Publication year - 1989
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(89)80931-7
Subject(s) - dna gyrase , dna supercoil , mutant , escherichia coli , dna , circular bacterial chromosome , biology , genetics , topoisomerase , gene , microbiology and biotechnology , dna replication
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 topA 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.