Promoter protection by a transcription factor acting as a local topological homeostat.
Binding of the Escherichia coli global transcription factor FIS to the upstream activating sequence (UAS) of stable RNA promoters activates transcription on the outgrowth of cells from stationary phase. Paradoxically, while these promoters require negative supercoiling of DNA for optimal activity, FIS counteracts the increase of negative superhelical density by DNA gyrase. We demonstrate that binding of FIS at the UAS protects the rrnA P1 promoter from inactivation at suboptimal superhelical densities. This effect is correlated with FIS-dependent constraint of writhe and facilitated untwisting of promoter DNA. We infer that FIS maintains stable RNA transcription by stabilizing local writhe in the UAS. These results suggest a novel mechanism of transcriptional regulation by a transcription factor acting as a local topological homeostat.
Rochman
Mark
M
Max Planck Institute for terrestrial Microbiology, Karl-von-Frisch-Strasse, D-35043 Marburg, Germany.
Aviv
Michal
M
Glaser
Gad
G
Muskhelishvili
Georgi
G
D049933:Aminocoumarins; D002352:Carrier Proteins / Q000378:metabolism*; D003374:Coumarins / Q000378:metabolism; D027081:DNA Gyrase / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins / Q000378:metabolism*; D035021:Factor For Inversion Stimulation Protein; D005786:Gene Expression Regulation; D034982:Integration Host Factors; D009154:Mutation; D009675:Novobiocin / Q000378:metabolism; D011401:Promoter Regions, Genetic; D059005:Topoisomerase II Inhibitors; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D049933:Aminocoumarins; D002352:Carrier Proteins; D003374:Coumarins; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; D034982:Integration Host Factors; D059005:Topoisomerase II Inhibitors; D014157:Transcription Factors; C440502:integration host factor, E coli; D009675:Novobiocin; D027081:DNA Gyrase; C004628:coumermycin