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Promoter selectivity control of Escherichia coli RNA polymerase by ionic strength: differential recognition of osmoregulated promoters by Eσ D and Eσ S holoenzymes
Author(s) -
Ding Qingquan,
Kusano Shuichi,
Villarejo Merna,
Ishihama Akira
Publication year - 1995
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.1365-2958.1995.tb02427.x
Subject(s) - sigma factor , rna polymerase , promoter , biology , transcription (linguistics) , sigma , microbiology and biotechnology , escherichia coli , ionic strength , biochemistry , gene expression , gene , chemistry , linguistics , philosophy , physics , quantum mechanics , aqueous solution
Summary Transcription in vitro of two osmoregulated promoters, for the Escherichia coli osmB and osmY genes, was analysed using two species of RNA polymerase holoenzyme reconstituted from purified core enzyme and either σ D (σ 70 , the major σ in exponentially growing cells) or σ S (σ 38 , the principal σ at stationary growth phase). Under conditions of low ionic strength, the osmB and osmY promoters were transcribed by both Eσ D and Eσ S . Addition of up to 400 mM potassium glutamate (K glutamate), mimicking the intracellular ionic conditions under hyper‐osmotic stress, specifically enhanced transcription at these promoters by Eσ S but inhibited that by Eσ D . At similar high concentrations of potassium chloride (KCI), however, initiation at both these promoters was virtually undetectable. These data suggest that the RNA polymerase, Eσ S , itself can sense osmotic stress by responding to changes in intracellular K glutamate concentrations and altering its promoter selectivity in order to recognize certain osmoregulated promoters.