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Effects of the Escherichia coli DNA‐binding protein H‐NS on rRNA synthesis in vivo
Author(s) -
Afflerbach Henning,
Schröder Oliver,
Wagner Rolf
Publication year - 1998
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.1365-2958.1998.00829.x
Subject(s) - biology , ribosomal rna , derepression , transcription (linguistics) , effector , rna , stringent response , microbiology and biotechnology , protein biosynthesis , ribosome , escherichia coli , biochemistry , gene expression , psychological repression , gene , philosophy , linguistics
The Escherichia coli DNA‐binding protein H‐NS is known to interact specifically with the upstream region of ribosomal RNA transcription units, where it causes transcriptional repression in vitro . Here, we present results demonstrating the effect of H‐NS on rRNA transcription in vivo . rRNA synthesis rates were compared in cells that differ in the expression of functional H‐NS or FIS molecules. We could show that in the absence of H‐NS derepression of rRNA synthesis occurs at low growth rates. During the cell cycle H‐NS is responsible for the rapid shut‐off of rRNA synthesis at the end of the exponential phase. As it is known for FIS‐dependent activation, the inhibitory function of H‐NS is specific for P1, the first of the tandem rRNA promoters. The effect of H‐NS on rRNA synthesis was further assessed under stress conditions. While under osmotic upshift the reduction in rRNA synthesis is clearly H‐NS‐dependent, no such influence could be detected at cold shock. Determination of the cellular ppGpp concentrations revealed that H‐NS does not mediate its function via alterations in the synthesis of the global effector ppGpp.