A High‐Affinity Calmodulin‐Binding Site in the CyaA Toxin Translocation Domain is Essential for Invasion of Eukaryotic Cells

Alexis Voegele (1, 2) , Mirko Sadi (1, 2) , Darragh Patrick O'Brien (1) , Pauline Gehan (3) , Dorothée Raoux‐barbot (1) , Maryline Davi (1) , Sylviane Hoos (4) , Sébastien Brûlé (4) , Bertrand Raynal (4) , Patrick Weber (5) , Ariel Mechaly (5) , Ahmed Haouz (5) , Nicolas Rodriguez (3) , Patrice Vachette (6) , Dominique Durand (6) , Sébastien Brier (7) , Daniel Ladant (1) , Alexandre Chenal (1)

1 Biochimie des Interactions Macromoléculaires / Biochemistry of Macromolecular Interactions
2 UPCité - Université Paris Cité
3 LBM UMR 7203 - Laboratoire des biomolécules
4 Biophysique Moléculaire (plateforme) - Molecular Biophysics (platform)
5 Cristallographie (Plateforme) - Crystallography (Platform)
6 I2BC - Institut de Biologie Intégrative de la Cellule
7 Plateforme technologique de RMN biologique - Biological NMR Technological Platform

The molecular mechanisms and forces involved in the translocation of bacterial toxins into host cells are still a matter of intense research. The adenylate cyclase (CyaA) toxin from Bordetella pertussis displays a unique intoxication pathway in which its catalytic domain is directly translocated across target cell membranes. The CyaA translocation region contains a segment, P454 (residues 454-484), which exhibits membrane-active properties related to antimicrobial peptides. Herein, the results show that this peptide is able to translocate across membranes and to interact with calmodulin (CaM). Structural and biophysical analyses reveal the key residues of P454 involved in membrane destabilization and calmodulin binding. Mutational analysis demonstrates that these residues play a crucial role in CyaA translocation into target cells. In addition, calmidazolium, a calmodulin inhibitor, efficiently blocks CyaA internalization. It is proposed that after CyaA binding to target cells, the P454 segment destabilizes the plasma membrane, translocates across the lipid bilayer and binds calmodulin. Trapping of CyaA by the CaM:P454 interaction in the cytosol may assist the entry of the N-terminal catalytic domain by converting the stochastic motion of the polypeptide chain through the membrane into an efficient vectorial chain translocation into host cells.

Keywords: adenylate cyclase; Bordetella pertussis; calmodulin; CyaA toxin; membrane translocation; protein membrane interaction; protein–protein interactions

Domains: Life Sciences [q-bio]; Biochemistry, Molecular Biology; Biophysics; Life Sciences [q-bio]; Biochemistry, Molecular Biology; Biochemistry [q-bio.BM]; Life Sciences [q-bio]; Biochemistry, Molecular Biology; Molecular biology; Life Sciences [q-bio]; Biochemistry, Molecular Biology; Structural Biology [q-bio.BM]

Alexis Voegele, Mirko Sadi, Darragh Patrick O'Brien, Pauline Gehan, Dorothée Raoux‐barbot, et al.. A High‐Affinity Calmodulin‐Binding Site in the CyaA Toxin Translocation Domain is Essential for Invasion of Eukaryotic Cells. Advanced Science, 2021, pp.2003630. ⟨10.1002/advs.202003630⟩. ⟨pasteur-03211832⟩