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Discoordinate gene expression of gyr A and gyrB in response to DNA gyrase inhibition in Escherichia coli
Author(s) -
Neumann Susanne,
Quiñones Ariel
Publication year - 1997
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.3620370109
Subject(s) - dna gyrase , dna supercoil , biology , gene , dna , circular bacterial chromosome , topoisomerase , gene expression , genetics , microbiology and biotechnology , regulation of gene expression , escherichia coli , dna replication
The intracellular level of DNA supercoiling is regulated in Escherichia coli by a homeostatic control mechanism that includes DNA gyrase and topoisomerase I gene expression. Despite several biochemical and genetical evidence that supports the existence of a homeostatic regulation mechanism, there are only few studies focusing gyr A and gyrB gene expression in connection to the mechanism involved in the regulation of DNA supercoiling in vivo . To study DNA gyrase gene expression and to be able to isolate mutants with altered expression of DNA gyrase, we constructed a new chromosomal reporter system based on two translational fusions of gyr A and gyrB to lacZ . Using this stable monitor system in a robust wild type, we simultaneously studied the influence of several inhibitors of DNA gyrase (quinolones and coumarins) on gyr A and gyrB gene expression as well as on the intracellular level of DNA supercoiling. Surprisingly, we found a delayed and differential response of gyr A and gyrB gene expression following inhibition of DNA gyrase by quinolones or coumarins. Whereas both groups of drugs were able to increase the expression of gyr A, the gyrB gene expression was only induced by the coumarins. Although the action of the quinolones was able to alter DNA supercoiling, we never observed any induction of gyrB from the chromosome. These results revealed that the gene expression of gyr A appears to be more sensitive to alterations in DNA supercoiling than the gyrB gene expression and suggest that probably additional regulatory mechanisms on the post‐translational level might be involved in the regulation of DNA supercoiling and DNA gyrase gene expression.