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σ S ‐dependent growth‐phase induction of the csgBA promoter in Escherichia coli can be achieved in vivo by σ 70 in the absence of the nucleoid‐associated protein H‐NS
Author(s) -
Arnqvist Anna,
Olsén Arne,
Normark Staffan
Publication year - 1994
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1994.tb00493.x
Subject(s) - rpos , biology , operon , transcription (linguistics) , promoter , microbiology and biotechnology , escherichia coli , sigma factor , repressor , gene , transcription factor , gene expression , genetics , linguistics , philosophy
Summary The stationary‐phase‐specific sigma factor σ S (RpoS/KatF) is required for Escherichia coli to induce expression of fibronectin‐binding curli organelles upon reaching stationary phase. We show that the csgA gene which encodes the curlin subunit protein belongs to a dicistronic operon, csgBA. The transcriptional start site of csgBA was determined and an AT‐rich upstream activating sequence (UAS) required for transcriptional activation was identified. The pcsgBA promoter is not specific for σ S since the same promoter sequence can be used by Eσ 70 in vivo in a strain lacking nucleoid‐associated protein H‐NS and σ S . Transcription remained growth‐phase induced and dependent upon the UAS in such a double mutant. Furthermore, we demonstrate that an additional operon, hdeAB , which is also dependent upon σ S for transcription, can be transcribed by Eσ 70 in vivo in the absence of H‐NS by utilizing the phdeAB promoter. Two other genes known to be under the control of σ S for expression, bolA and katE , remained transcriptionally silent in the absence of H‐NS. It is suggested that a subset of E. coli promoters can be recognized by both Eσ S and Eσ 70 in vivo but H‐NS interacting with these sequences prevents formation of succesful transcription‐initiation complexes with Eσ 70 .