The expression of the Escherichia coli fis gene is strongly dependent on the superhelical density of DNA.
The Escherichia coli DNA architectural protein FIS is a pleiotropic regulator, which couples the cellular physiology with transitions in the superhelical density of bacterial DNA. Recently, we have shown that this effect is in part mediated via DNA gyrase, the major cellular topoisomerase responsible for the elevation of negative supercoiling. Here, we demonstrate that, in turn, the expression of the fis gene strongly responds to alterations in the topology of DNA in vivo, being maximal at high levels of negative supercoiling. Any deviations from these optimal levels decrease fis promoter activity. This strict dependence of fis expression on the superhelical density suggests that fis may be involved in 'fine-tuning' the homeostatic control mechanism of DNA supercoiling in E. coli.
Schneider
R
R
Institut für Genetik und Mikrobiologie, LMU München, Maria-Ward-Str. 1a, 80638 München, Germany.
Travers
A
A
Muskhelishvili
G
G
D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D004278:DNA, Superhelical / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D034982:Integration Host Factors; D008969:Molecular Sequence Data; D014158:Transcription, Genetic
D002352:Carrier Proteins; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; D034982:Integration Host Factors; C440502:integration host factor, E coli