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The alarmone (p)ppGpp mediates physiological‐responsive control at the σ 54 ‐dependent Po promoter
Author(s) -
Sze Chun Chau,
Shingler Victoria
Publication year - 1999
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 - 10.1046/j.1365-2958.1999.01264.x
Subject(s) - stringent response , biology , operon , transcription (linguistics) , rna polymerase , transcriptional regulation , auxotrophy , regulation of gene expression , microbiology and biotechnology , escherichia coli , biochemistry , transcription factor , gene , linguistics , philosophy
Transcription from the Pseudomonas ‐derived σ 54 ‐dependent Po promoter of the dmp operon is mediated by the aromatic‐responsive regulator DmpR. However, physiological control is superimposed on this regulatory system causing silencing of the DmpR‐mediated transcriptional response in rich media until the transition between exponential and stationary phase is reached. Here, the positive role of the nutritional alarmone (p)ppGpp in DmpR regulation of the Po promoter has been identified and investigated in vivo . Overproduction of (p)ppGpp in a Pseudomonas reporter system was found to allow an immediate transcriptional response under normally non‐permissive conditions. Conversely (p)ppGpp‐deficient Escherichia coli strains were found to be severely defective in DmpR‐mediated transcription, demonstrating the requirement for this metabolic signal. A subset of mutations in the β, β′ and σ 70 subunits of RNA polymerase, which confer prototrophy on ppGpp 0 E. coli , was also found to restore specific DmpR‐mediated transcription from Po, suggesting that the metabolic signal is mediated directly through the σ 54 ‐RNA polymerase. These data provide a direct mechanistic link between the physiological status of the cell and expression from σ 54 promoters.