Stationary phase induction of dnaN and recF, two genes of Escherichia coli involved in DNA replication and repair.
The beta subunit of DNA polymerase III holoenzyme, the Escherichia coli chromosomal replicase, is a sliding DNA clamp responsible for tethering the polymerase to DNA and endowing it with high processivity. The gene encoding beta, dnaN, maps between dnaA and recF, which are involved in initiation of DNA replication at oriC and resumption of DNA replication at disrupted replication forks, respectively. In exponentially growing cells, dnaN and recF are expressed predominantly from the dnaA promoters. However, we have found that stationary phase induction of the dnaN promoters drastically changes the expression pattern of the dnaA operon genes. As a striking consequence, synthesis of the beta subunit and RecF protein increases when cell metabolism is slowing down. Such an induction is dependent on the stationary phase sigma factor, RpoS, although the accumulation of this factor alone is not sufficient to activate the dnaN promoters. These promoters are located in DNA regions without static bending, and the -35 hexamer element is essential for their RpoS-dependent induction. Our results suggest that stationary phase-dependent mechanisms have evolved in order to coordinate expression of dnaN and recF independently of the dnaA regulatory region. These mechanisms might be part of a developmental programme aimed at maintaining DNA integrity under stress conditions.
Villarroya
M
M
Instituto de Investigaciones Citológicas, Fundación Valenciana de Investigaciones Biomedicas, Valencia 46010, Spain.
Pérez-Roger
I
I
Macián
F
F
Armengod
M E
ME
D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology; D004260:DNA Repair / Q000235:genetics; D004261:DNA Replication / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D004259:DNA-Directed DNA Polymerase; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D009154:Mutation; D009876:Operon / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D014176:Protein Biosynthesis / Q000235:genetics; D012329:RNA, Bacterial / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins; D012808:Sigma Factor / Q000235:genetics / Q000502:physiology; D014158:Transcription, Genetic / Q000235:genetics
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria; D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D012808:Sigma Factor; C489340:recF protein, E coli; C069567:sigma factor KatF protein, Bacteria; C066218:recF protein, Bacteria; D004259:DNA-Directed DNA Polymerase; C083980:dnaN protein, Bacteria