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PLoS Pathog. 2015 Mar 4;11(3):e1004700. doi: 10.1371/journal.ppat.1004700. eCollection 2015 Mar.

Virulence regulation with Venus flytrap domains: structure and function of the periplasmic moiety of the sensor-kinase BvgS.

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Center for Infection and Immunity (CIIL), Institut Pasteur de Lille, Lille, France; Center for Infection and Immunity (CIIL), University Lille North of France, Lille, France; UMR 8204, Centre National de la Recherche Scientifique (CNRS), Lille, France; U1019, Institut National de la Santé et de la Recherche Médicale (INSERM), Lille, France.
Unité de Glycobiologie Structurale et Fonctionnelle, CNRS UMR8576, University Lille North of France, Villeneuve d'Ascq, France.
Laboratory of Biopolymers and Supramolecular Nanomaterials, Université Libre de Bruxelles, Brussels, Belgium.
Structural Biology Laboratory, University of York, York, England, United Kingdom.
Research Complex at Harwell, Science and Technology Facilities Council Rutherford Appleton Laboratory, Didcot, England, United Kingdom.
Department of Biochemistry & Molecular Biology, University of Chicago, Chicago, Illinois, United States of America.


Two-component systems (TCS) represent major signal-transduction pathways for adaptation to environmental conditions, and regulate many aspects of bacterial physiology. In the whooping cough agent Bordetella pertussis, the TCS BvgAS controls the virulence regulon, and is therefore critical for pathogenicity. BvgS is a prototypical TCS sensor-kinase with tandem periplasmic Venus flytrap (VFT) domains. VFT are bi-lobed domains that typically close around specific ligands using clamshell motions. We report the X-ray structure of the periplasmic moiety of BvgS, an intricate homodimer with a novel architecture. By combining site-directed mutagenesis, functional analyses and molecular modeling, we show that the conformation of the periplasmic moiety determines the state of BvgS activity. The intertwined structure of the periplasmic portion and the different conformation and dynamics of its mobile, membrane-distal VFT1 domains, and closed, membrane-proximal VFT2 domains, exert a conformational strain onto the transmembrane helices, which sets the cytoplasmic moiety in a kinase-on state by default corresponding to the virulent phase of the bacterium. Signaling the presence of negative signals perceived by the periplasmic domains implies a shift of BvgS to a distinct state of conformation and activity, corresponding to the avirulent phase. The response to negative modulation depends on the integrity of the periplasmic dimer, indicating that the shift to the kinase-off state implies a concerted conformational transition. This work lays the bases to understand virulence regulation in Bordetella. As homologous sensor-kinases control virulence features of diverse bacterial pathogens, the BvgS structure and mechanism may pave the way for new modes of targeted therapeutic interventions.

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