Suppressors of DnaAATP imposed overinitiation in Escherichia coli

Godefroid Charbon, Leise Riber, Malene Cohen, Ole Skovgaard, Kazuyuki Fujimitsu, Tsutomu Katayama, Anders Løbner-Olesen

    Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

    Abstract

    Chromosome replication in Escherichia coli is limited by the supply of DnaA associated with ATP. Cells deficient in RIDA (Regulatory Inactivation of DnaA) due to a deletion of the hda gene accumulate suppressor mutations (hsm) to counteract the overinitiation caused by an elevated DnaAATP level. Eight spontaneous hda suppressor mutations were identified by whole-genome sequencing, and three of these were analysed further. Two mutations (hsm-2 and hsm-4) mapped in the dnaA gene and led to a reduced ability to initiate replication from oriC. One mutation (hsm-1) mapped to the seqA promoter and increased the SeqA protein level in the cell. hsm-1 cells had prolonged origin sequestration, reduced DnaA protein level and reduced DnaA-Reactivating Sequence (DARS)-mediated rejuvenation of DnaAADP to DnaAATP, all of which could contribute to the suppression of RIDA deficiency. Despite of these defects hsm-1 cells were quite similar to wild type with respect to cell cycle parameters. We speculate that since SeqA binding sites might overlap with DnaA binding sites spread throughout the chromosome, excess SeqA could interfere with DnaA titration and thereby increase free DnaA level. Thus, in spite of reduction in total DnaA, the amount of DnaA molecules available for initiation may not be reduced.

    OriginalsprogEngelsk
    TidsskriftMolecular Microbiology
    Vol/bind79
    Udgave nummer4
    Sider (fra-til)914-928
    ISSN0950-382X
    DOI
    StatusUdgivet - 2011

    Citer dette

    Charbon, G., Riber, L., Cohen, M., Skovgaard, O., Fujimitsu, K., Katayama, T., & Løbner-Olesen, A. (2011). Suppressors of DnaAATP imposed overinitiation in Escherichia coli. Molecular Microbiology, 79(4), 914-928. https://doi.org/10.1111/j.1365-2958.2010.07493.x