Effects of the Escherichia coli DNA-binding protein H-NS on rRNA synthesis in vivo

Mol Microbiol. 1998 May;28(3):641-53. doi: 10.1046/j.1365-2958.1998.00829.x.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Chloramphenicol O-Acetyltransferase / biosynthesis
  • Chloramphenicol O-Acetyltransferase / genetics
  • Cold Temperature
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Escherichia coli / genetics
  • Escherichia coli / growth & development
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins*
  • Factor For Inversion Stimulation Protein
  • Gene Expression Regulation, Bacterial
  • Guanosine Tetraphosphate / metabolism
  • Integration Host Factors
  • Osmotic Pressure
  • Promoter Regions, Genetic
  • RNA, Bacterial / biosynthesis*
  • RNA, Ribosomal / biosynthesis*
  • Repressor Proteins
  • Transcription, Genetic
  • rRNA Operon*

Substances

  • Bacterial Proteins
  • Carrier Proteins
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • Factor For Inversion Stimulation Protein
  • H-NS protein, bacteria
  • Integration Host Factors
  • RNA, Bacterial
  • RNA, Ribosomal
  • Repressor Proteins
  • integration host factor, E coli
  • Guanosine Tetraphosphate
  • Chloramphenicol O-Acetyltransferase