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The σ S level in starving Escherichia coli cells increases solely as a result of its increased stability, despite decreased synthesis
Author(s) -
Zgurskaya H. I.,
Keyhan M.,
Matin A.
Publication year - 1997
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.1365-2958.1997.3961742.x
Subject(s) - rpos , biology , escherichia coli , chemostat , transcription (linguistics) , sigma factor , lac operon , methionine , protein biosynthesis , translation (biology) , stationary phase , microbiology and biotechnology , messenger rna , gene , biochemistry , biophysics , gene expression , bacteria , genetics , amino acid , rna polymerase , promoter , chemistry , linguistics , philosophy , chromatography
The σ S level in starving (stationary phase) Escherichia coli cells increases four‐ to sixfold following growth in a defined or a complex medium. Chemostat‐grown cells, subjected to increasing carbon starvation, also become progressively richer in σ S content. These increases occur despite reduced transcription of the σ S ‐encoding gene, rpoS , and translation of rpoS mRNA, and result solely from a large increase in the stability of the sigma protein. Previous results, based on rpoS :: lacZ transcriptional and translational fusions, and on methionine incorporation in σ S , had suggested increased synthesis of σ S in starving cells. Alternative explanations for these results consistent with the conclusions of this paper are discussed.