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σ 54 ‐RNA polymerase controls σ 70 ‐dependent transcription from a non‐overlapping divergent promoter
Author(s) -
Johansson Linda U. M.,
Solera Dafne,
Bernardo Lisandro M. D.,
Moscoso Joana A.,
Shingler Victoria
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.1365-2958.2008.06440.x
Subject(s) - biology , rna polymerase , transcription (linguistics) , microbiology and biotechnology , promoter , repressor , rna polymerase ii , gene , rna , genetics , transcription factor , gene expression , philosophy , linguistics
Summary Divergent transcription of a regulatory gene and a cognate promoter under its control is a common theme in bacterial regulatory circuits. This genetic organization is found for the dmpR gene that encodes the substrate‐responsive specific regulator of the σ 54 ‐dependent Po promoter, which controls (methyl)phenol catabolism. Here we identify the Pr promoter of dmpR as a σ 70 ‐dependent promoter that is regulated by a novel mechanism in which σ 54 ‐RNA polymerase occupancy of the non‐overlapping σ 54 ‐Po promoter stimulates σ 70 ‐Pr output. In addition, we show that DmpR stimulates its own production through Po activity both in vivo and in vitro . Hence, the demonstrated regulatory circuit reveals a novel role for σ 54 ‐RNA polymerase, namely regulation of a σ 70 ‐dependent promoter, and a new mechanism that places a single promoter under dual control of two alternative forms of RNA polymerase. We present a model in which guanosine tetra‐phosphate plays a major role in the interplay between σ 54 ‐ and σ 70 ‐dependent transcription to ensure metabolic integration to couple σ 70 ‐Pr output to both low‐energy conditions and the presence of substrate.