A novel hybrid kinase is essential for regulating the σB-mediated stress response of Bacillus cereus

Authors

  • Mark De Been,

    Corresponding author
    1. TI Food and Nutrition (TIFN), Wageningen, the Netherlands.
    2. Laboratory of Food Microbiology, Wageningen University and Research Centre, PO Box 8129, 6700 EV Wageningen, the Netherlands.
    3. Centre for Molecular and Biomolecular Informatics (CMBI), NCMLS, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands.
    Search for more papers by this author
  • Marcel H. Tempelaars,

    1. TI Food and Nutrition (TIFN), Wageningen, the Netherlands.
    2. Laboratory of Food Microbiology, Wageningen University and Research Centre, PO Box 8129, 6700 EV Wageningen, the Netherlands.
    Search for more papers by this author
  • Willem Van Schaik,

    1. Department of Medical Microbiology, University Medical Center Utrecht, Utrecht, the Netherlands.
    Search for more papers by this author
  • Roy Moezelaar,

    1. TI Food and Nutrition (TIFN), Wageningen, the Netherlands.
    2. Food Technology Centre, Wageningen University and Research Centre, Wageningen, the Netherlands.
    Search for more papers by this author
  • Roland J. Siezen,

    1. TI Food and Nutrition (TIFN), Wageningen, the Netherlands.
    2. Centre for Molecular and Biomolecular Informatics (CMBI), NCMLS, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands.
    3. NIZO food research BV, Ede, the Netherlands.
    Search for more papers by this author
  • Tjakko Abee

    1. TI Food and Nutrition (TIFN), Wageningen, the Netherlands.
    2. Laboratory of Food Microbiology, Wageningen University and Research Centre, PO Box 8129, 6700 EV Wageningen, the Netherlands.
    Search for more papers by this author

*E-mail mdebeen@cmbi.ru.nl; Tel. (+31) 317 482887; Fax (+31) 317 484978.

Summary

A common bacterial strategy for monitoring environmental challenges is to use two-component systems, which consist of a sensor histidine kinase (HK) and a response regulator (RR). In the food-borne pathogen Bacillus cereus, the alternative sigma factor σB is activated by the RR RsbY. Here we present strong indications that the PP2C-type phosphatase RsbY receives its input from the multi-sensor hybrid kinase BC1008 (renamed RsbK). Genome analyses revealed that, across bacilli, rsbY and rsbK are located in a conserved gene cluster. A B. cereus rsbK deletion strain was shown to be incapable of inducing σB upon stress conditions and was impaired in its heat adaptive response. Comparison of the wild-type and rsbK mutant transcriptomes upon heat shock revealed that RsbK was primarily involved in the activation of the σB-mediated stress response. Truncation of the RsbK RR receiver domain demonstrated the importance of this domain for σB induction upon stress. The domain architecture of RsbK suggests that in the B. cereus group and in other bacilli, environmental and intracellular stress signalling routes are combined into one single protein. This strategy is markedly different from the σB activation pathway in other low-GC Gram-positives.

Ancillary