Translocation and calmodulin-activation of the adenylate cyclase toxin (CyaA) of Bordetella pertussis

• Published in: Pathogens and disease 2018-11, Vol.76 (8)
• Main Authors: Voegele, Alexis, O’Brien, Darragh P, Subrini, Orso, Sapay, Nicolas, Cannella, Sara E, Enguéné, Véronique Yvette Ntsogo, Hessel, Audrey, Karst, Johanna, Hourdel, Véronique, Perez, Ana Cristina Sotomayor, Davi, Marilyne, Veneziano, Rémi, Chopineau, Joel, Vachette, Patrice, Durand, Dominique, Brier, Sébastien, Ladant, Daniel, Chenal, Alexandre
• Format: Article
• Language: English
• Subjects: Activation; Acylation; Adenylate cyclase; Bordetella pertussis; Calcium-binding protein; Calmodulin; Colonization; Cyclic AMP; Cytosol; Intoxication; Life Sciences; Lipid bilayers; Lipids; Membrane potential; Membranes; Pertussis; Respiratory tract; Secretion; Toxins; Translocation; Transport; Whooping cough
• ISSN: 2049-632X; 2049-632X
• DOI: 10.1093/femspd/fty085

Abstract The adenylate cyclase toxin (CyaA) is a multi-domain protein secreted by Bordetella pertussis, the causative agent of whooping cough. CyaA is involved in the early stages of respiratory tract colonization by Bordetella pertussis. CyaA is produced and acylated in the bacteria, and secreted via a dedicated secretion system. The cell intoxication process involves a unique mechanism of transport of the CyaA toxin catalytic domain (ACD) across the plasma membrane of eukaryotic cells. Once translocated, ACD binds to and is activated by calmodulin and produces high amounts of cAMP, subverting the physiology of eukaryotic cells. Here, we review our work on the identification and characterization of a critical region of CyaA, the translocation region, required to deliver ACD into the cytosol of target cells. The translocation region contains a segment that exhibits membrane-active properties, i.e. is able to fold upon membrane interaction and permeabilize lipid bilayers. We proposed that this region is required to locally destabilize the membrane, decreasing the energy required for ACD translocation. To further study the translocation process, we developed a tethered bilayer lipid membrane (tBLM) design that recapitulate the ACD transport across a membrane separating two hermetic compartments. We showed that ACD translocation is critically dependent on calcium, membrane potential, CyaA acylation and on the presence of calmodulin in the trans compartment. Finally, we describe how calmodulin-binding triggers key conformational changes in ACD, leading to its activation and production of supraphysiological concentrations of cAMP. The studies performed in our lab on the mechanism of translocation and calmodulin-activation of the CyaA catalytic domain are presented in this review.