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Promoter protection by a transcription factor acting as a local topological homeostat
Author(s) -
Rochman Mark,
Aviv Michal,
Glaser Gad,
Muskhelishvili Georgi
Publication year - 2002
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1093/embo-reports/kvf067
Subject(s) - promoter , dna supercoil , transcription (linguistics) , biology , transcription factor , dna , writhe , dna gyrase , rna , genetics , microbiology and biotechnology , gene , escherichia coli , gene expression , dna replication , linguistics , philosophy , geometry , mathematics , twist
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.