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Promoter specificity for 6S RNA regulation of transcription is determined by core promoter sequences and competition for region 4.2 of σ 70
Author(s) -
Cavanagh Amy T.,
Klocko Andrew D.,
Liu Xiaochun,
Wassarman Karen M.
Publication year - 2008
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.1365-2958.2008.06117.x
Subject(s) - promoter , biology , transcription (linguistics) , rna , rna polymerase , rna polymerase ii , microbiology and biotechnology , transcription factor ii d , gene expression , gene , genetics , linguistics , philosophy
Summary 6S RNA binds σ 70 ‐RNA polymerase and downregulates transcription at many σ 70 ‐dependent promoters, but others escape regulation even during stationary phase when the majority of the transcription machinery is bound by the RNA. We report that core promoter elements determine this promoter specificity; a weak −35 element allows a promoter to be 6S RNA sensitive, and an extended −10 element similarly determines 6S RNA inhibition except when a consensus −35 element is present. These two features together predicted that hundreds of mapped Escherichia coli promoters might be subject to 6S RNA dampening in stationary phase. Microarray analysis confirmed 6S RNA‐dependent downregulation of expression from 68% of the predicted genes, which corresponds to 49% of the expressed genes containing mapped E. coli promoters and establishes 6S RNA as a global regulator in stationary phase. We also demonstrate a critical role for region 4.2 of σ 70 in RNA polymerase interactions with 6S RNA. Region 4.2 binds the −35 element during transcription initiation; therefore we propose one mechanism for 6S RNA regulation of transcription is through competition for binding region 4.2 of σ 70 .