title: Effects of the Escherichia coli DNA-binding protein H-NS on rRNA synthesis in vivo.
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.
authors.affiliation: Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Afflerbach
authors.forename: O
authors.initials: O
authors.lastname: Schröder
authors.forename: R
authors.initials: R
authors.lastname: Wagner
mesh_terms: D001426:Bacterial Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis / Q000235:genetics; D003080:Cold Temperature; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; D015964:Gene Expression Regulation, Bacterial; D006159:Guanosine Tetraphosphate / Q000378:metabolism; D034982:Integration Host Factors; D009997:Osmotic Pressure; D011401:Promoter Regions, Genetic; D012329:RNA, Bacterial / Q000096:biosynthesis*; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D012097:Repressor Proteins; D014158:Transcription, Genetic; D012407:rRNA Operon
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; C031908:H-NS protein, bacteria; D034982:Integration Host Factors; D012329:RNA, Bacterial; D012335:RNA, Ribosomal; D012097:Repressor Proteins; C440502:integration host factor, E coli; D006159:Guanosine Tetraphosphate; D015500:Chloramphenicol O-Acetyltransferase