DnaA-ATP acts as a molecular switch to control levels of ribonucleotide reductase expression in Escherichia coli.

Anne Olliver (1) , Chiara Saggioro (1) , John Herrick , Bianca Sclavi (1)

1 LBPA - Laboratoire de Biologie et de Pharmacologie Appliquée

Ribonucleotide reductase (RNR) is the bottleneck enzyme in the synthesis of dNTPs required for DNA replication. In order to avoid the mutagenic effects of imbalances in dNTPs the amount and activity of RNR enzyme in the cell is tightly regulated. RNR expression from the nrdAB operon is thus coupled to coincide with the initiation of DNA replication. However the mechanism for the coordination of gene transcription and DNA replication remains to be elucidated. The timing and synchrony of DNA replication initiation in Escherichia coli is controlled in part by the binding of the DnaA protein to the origin of replication. DnaA is also a transcription factor of the nrdAB operon and could thus be the link between these two processes. Here we show that RNA polymerase can form a stable transcription initiation complex at the nrdAB promoter by direct interaction with the far upstream sites required for the timing of expression as a function of DNA replication. In addition, we show that the binding of DnaA on the promoter can either activate or repress transcription as a function of its concentration and its nucleotide-bound state. However, transcription regulation by DnaA does not significantly affect the timing of expression of RNR.

Mots clés: Life Sciences

Anne Olliver, Chiara Saggioro, John Herrick, Bianca Sclavi. DnaA-ATP acts as a molecular switch to control levels of ribonucleotide reductase expression in Escherichia coli.. Molecular Microbiology, 2010, 76 (6), pp.1555. ⟨10.1111/j.1365-2958.2010.07185.x⟩. ⟨hal-00552635⟩