A novel two-component system controls the expression of Pseudomonas aeruginosa fimbrial cup genes

Authors

  • Hemantha D. Kulasekara,

    1. Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Ave, Boston, MA 02115, USA.
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  • Isabelle Ventre,

    1. Laboratoire d’Ingenierie des Systemes Macromoleculaires, UPR9027, IBSM/CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
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  • Bridget R. Kulasekara,

    1. Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Ave, Boston, MA 02115, USA.
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  • Andrée Lazdunski,

    1. Laboratoire d’Ingenierie des Systemes Macromoleculaires, UPR9027, IBSM/CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
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  • Alain Filloux,

    1. Laboratoire d’Ingenierie des Systemes Macromoleculaires, UPR9027, IBSM/CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
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  • Stephen Lory

    Corresponding author
    1. Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Ave, Boston, MA 02115, USA.
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E-mail stephen_lory@hms.harvard.edu; Tel. (+1) 617 432 5099; Fax (+1) 617 736 7664.

Summary

Biofilm formation by the opportunistic pathogen Pseudomonas aeruginosa requires the expression of a number of surface adhesive components. The expression of surface organelles facilitating biofilm formation is controlled by environmental signals acting through transcriptional regulatory networks. We analysed the expression of a family of P. aeruginosa adhesins encoded by three distinct fimbrial gene clusters (cupA, cupB and cupC). Using transposon mutagenesis, we have identified several regulatory loci that upregulated cupB and cupC transcription. One such locus contains three components, RocS1, RocR and RocA1, which represent a variant of a classical two-component signal transduction pathway. RocS1 is a sensor kinase, RocA1 is a DNA binding response regulator that activates cup genes, and RocR is an antagonist of RocA1 activity. Using a two-hybrid assay, we have shown that RocS1 interacts with receiver domains of both RocA1 and RocR. Expression of the Cup system in response to environmental stimuli is accomplished by a novel mechanism in which the sensor kinase activates its cognate response regulator through a phosphorelay pathway, while an additional repressor protein modulates this interaction.

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