In electro-phoretic mobility-shift assays , Fis was found to bind to both the gyrA of S. enterica , despite the strong divergence from the E. coli sequence on the part of the former .
The retention of Fis-mediated repression of gyrA in S. enterica despite the radically different nucleotide sequence found immediately upstream of the Pribnow box is indicative of the physiological importance for the cell of regulation of gyrase expression by Fis .
Fis also binds to and represses the promoters of the gyrA genes in both E. coli and S. Typhimurium , resulting in reduced levels of DNA supercoiling .
In E. coli , FIS binds the gyrA promoters to repress their expression ; similarly , FIS has been found to repress S. enterica gyrA .
Therefore the observed differences in FIS control of DNA supercoiling suggested that the role of FIS in the regulation of gyrA might differ between the two species .
Therefore the observed differences in FIS control of DNA supercoiling suggested that the role of FIS in the regulation of gyrA might differ between the two species .
FIS control of gyrA .