FIS is a regulator of metabolism in Escherichia coli (original) (raw)
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The E.coli fis promoter is subject to stringent control and autoregulation
The EMBO Journal, 1992
The DNA binding protein FIS is involved in processes like site specific DNA inversion, X excision and stinulation of stable RNA synthesis in Escherichia coli. The amount of FIS protein is subject to dramatic changes during growth. We demonstrate thatfis is part of an operon with one ORF of unknown function preceding the fis gene. Regulation of fis synthesis occurs at the transcriptional level. Within 15 min after nutritional upshift a large burst offis mRNA is produced which levels off when cells begin to grow. By mutational analysis using promoter-lacZ fusions we demonstrate that the fis promoter is autoregulated by FIS. Growth phase regulation of the fis promoter depends on the presence of a GC motif downstream of the-10 region. We show that the fis promoter is subject to stringent control and discuss this unusual feature with respect to the known and putative functions FIS serves in E.coli.
E.coli Fis protein activates ribosomal RNA transcription in vitro and in vivo
The EMBO journal, 1990
An upstream activation region (UAR) contributes to the extremely high activity of the Escherichia coli ribosomal RNA promoter, rrnB P1, increasing its activity 20- to 30-fold over that of the same promoter lacking the UAR. We have used DNase footprinting to define three specific sites in the rrnB P1 UAR that bind Fis, a protein identified previously by its role in recombinational enhancer function in other systems. We find that purified Fis activates transcription from promoters containing these sites 10- to 20-fold in vitro at concentrations correlating with the filling of these sites. Three approaches indicate that Fis contributes to the function of the UAR in vivo. First, there is a progressive loss in the activity of rrnB P1-lacZ fusions as Fis binding sites are deleted. Second, an rrnB P1 promoter with a mutation in a Fis binding site has 5-fold reduced transcription activity in vivo, dramatically reduced Fis binding in vitro, and shows no Fis dependent transcription activation...
Microbiology, 2008
Expression from the Escherichia coli W meta-hpa operon promoter (Pg) is under a strict catabolic repression control mediated by the cAMP-catabolite repression protein (CRP) complex in a glucose-containing medium. The Pg promoter is also activated by the integration host factor (IHF) and repressed by the specific transcriptional regulator HpaR when 4-hydroxyphenylacetate (4HPA) is not present in the medium. Expression from the hpa promoter is also repressed in undefined rich medium such as LB, but the molecular basis of this mechanism is not understood. We present in vitro and in vivo studies to demonstrate the involvement of FIS protein in this catabolic repression. DNase I footprinting experiments show that FIS binds to multiple sites within the Pg promoter. FIS-site I overlaps the CRP-binding site. By using an electromobility shift assay, we demonstrated that FIS efficiently competes with CRP for binding to the Pg promoter, suggesting an antagonist/competitive mechanism. RT-PCR showed that the Pg repression effect is relieved in a FIS deleted strain. The repression role of FIS at Pg was further demonstrated by in vitro transcription assays. These results suggest that FIS contributes to silencing the Pg promoter in the exponential phase of growth in an undefined rich medium when FIS is predominantly expressed.
Journal of bacteriology, 1992
In Escherichia coli transcription of the tRNA operon thrU (tufB) and the rRNA operon rrnB is trans-activated by the protein FIS. This protein, which stimulates the inversion of various viral DNA segments, binds specifically to a cis-acting sequence (designated UAS) upstream of the promoter of thrU (tufB) and the P1 promoter of the rrnB operon. There are indications that this type of regulation is representative for the regulation of more stable RNA operons. In the present investigation we have studied UAS-dependent transcription activation of the thrU (tufB) operon in the presence and absence of FIS during a normal bacterial growth cycle and after a nutritional shift-up. In early log phase the expression of the operon rises steeply in wild-type cells, whereafter it declines. Concomitantly, a peak of the cellular FIS concentration is observed. Cells in the stationary phase are depleted of FIS. The rather abrupt increase of transcription activation depends on the nutritional quality o...
Downregulation of the Escherichia coli guaB promoter by FIS
Microbiology-sgm, 2008
The Escherichia coli guaB promoter (P guaB ) regulates transcription of two genes, guaB and guaA, that are required for the synthesis of guanosine 59-monophosphate (GMP), a precursor for the synthesis of guanine nucleoside triphosphates. Transcription from P guaB increases as a function of increasing cellular growth rate, and this is referred to as growth rate-dependent control (GRDC).
Molecular Microbiology, 2003
acs encodes acetyl-coenzyme A synthetase, a highaffinity enzyme that allows cells to scavenge for acetate during carbon starvation. CRP activates acs transcription by binding tandem DNA sites located upstream of the major promoter, acs P2. Here, we used electrophoretic mobility shift assays and DNase I footprint analyses to demonstrate that the nucleoid proteins FIS and IHF each bind multiple sites within the acs regulatory region, that FIS competes successfully with CRP for binding to their overlapping and neighbouring sites and that IHF binds independently of either FIS or CRP. Using in vitro transcription assays, we demonstrated that FIS and IHF independently reduce CRP-dependent acs transcription. Using in vivo reporter assays, we showed that disruption of DNA sites for FIS or deletion of DNA sites for IHF increases acs transcription. We propose that FIS and IHF each function directly as anti-activators of CRP, each working independently at different times during growth to set the levels of CRP-dependent acs transcription.
The role of FIS in trans activation of stable RNA operons of E. coli
The EMBO Journal, 1990
The EMBO Journal vol.9 no.3 pp.727-734, 1990 ... The role of FIS in trans activation of stable RNA ... Lars Nilsson1, Anne Vanet, Erik Vijgenboom and Leendert Bosch ... Department of Biochemistry, Leiden University, Gorlaeus Laboratories, 2333 AL Leiden, The ...
Molecular Microbiology, 2010
Ribonucleotide reductase (RNR) is the bottleneck enzyme in the synthesis of dNTPs 2 required for DNA replication. In order to avoid the mutagenic effects of imbalances in dNTPs 3 the amount and activity of RNR enzyme in the cell is tightly regulated. RNR expression from 4 the nrdAB operon is thus coupled to coincide with the initiation of DNA replication. However 5 the mechanism for the coordination of gene transcription and DNA replication remains to be 6 elucidated. The timing and synchrony of DNA replication initiation in Escherichia coli is 7 controlled in part by the binding of the DnaA protein to the origin of replication. DnaA is also 8 a transcription factor of the nrdAB operon and could thus be the link between these two 9 processes. Here we show that RNA polymerase can form a stable transcription initiation 10 complex at the nrdAB promoter by direct interaction with the far upstream sites required for 11 the timing of expression as a function of DNA replication. In addition, we show that the 12 binding of DnaA on the promoter can either activate or repress transcription as a function of 13 its concentration and its nucleotide-bound state. However, transcription regulation by DnaA 14 does not significantly affect the timing of expression of RNR from the nrdAB operon.