title: The DnaA Protein Is Not the Limiting Factor for Initiation of Replication in Escherichia coli.
abstract: The bacterial replication cycle is driven by the DnaA protein which cycles between the active ATP-bound form and the inactive ADP-bound form. It has been suggested that DnaA also is the main controller of initiation frequency. Initiation is thought to occur when enough ATP-DnaA has accumulated. In this work we have performed cell cycle analysis of cells that contain a surplus of ATP-DnaA and asked whether initiation then occurs earlier. It does not. Cells with more than a 50% increase in the concentration of ATP-DnaA showed no changes in timing of replication. We suggest that although ATP-DnaA is the main actor in initiation of replication, its accumulation does not control the time of initiation. ATP-DnaA is the motor that drives the initiation process, but other factors will be required for the exact timing of initiation in response to the cell's environment. We also investigated the in vivo roles of datA dependent DnaA inactivation (DDAH) and the DnaA-binding protein DiaA. Loss of DDAH affected the cell cycle machinery only during slow growth and made it sensitive to the concentration of DiaA protein. The result indicates that compromised cell cycle machines perform in a less robust manner.
authors.affiliation: Department of Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
authors.forename: Ingvild
authors.initials: I
authors.lastname: Flåtten
authors.affiliation: Department of Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
authors.forename: Solveig
authors.initials: S
authors.lastname: Fossum-Raunehaug
authors.affiliation: Department of Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
authors.forename: Riikka
authors.initials: R
authors.lastname: Taipale
authors.affiliation: Department of Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
authors.forename: Silje
authors.initials: S
authors.lastname: Martinsen
authors.affiliation: Department of Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Skarstad
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C523634:DiaA protein, E coli; C066312:DnaA protein, Bacteria; D000255:Adenosine Triphosphate