Dataset Information

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

ABSTRACT: 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.

SUBMITTER: Voegele A

PROVIDER: S-EPMC8097335 | biostudies-literature | 2021 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

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

Voegele Alexis A Sadi Mirko M O'Brien Darragh Patrick DP Gehan Pauline P Raoux-Barbot Dorothée D Davi Maryline M Hoos Sylviane S Brûlé Sébastien S Raynal Bertrand B Weber Patrick P Mechaly Ariel A Haouz Ahmed A Rodriguez Nicolas N Vachette Patrice P Durand Dominique D Brier Sébastien S Ladant Daniel D Chenal Alexandre A

Advanced science (Weinheim, Baden-Wurttemberg, Germany) 20210308 9

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 <i>Bordetella pertussis</i> 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 re ...[more]

PMID: 33977052

Similar Datasets

Project description:The emergence and continued dominance of a Streptococcus pyogenes (group A Streptococcus, GAS) M1T1 clonal group is temporally correlated with acquisition of genomic sequences that confer high level expression of cotoxins streptolysin O (SLO) and NAD+-glycohydrolase (NADase). Experimental infection models have provided evidence that both toxins are important contributors to GAS virulence. SLO is a cholesterol-dependent pore-forming toxin capable of lysing virtually all types of mammalian cells. NADase, which is composed of an N-terminal translocation domain and C-terminal glycohydrolase domain, acts as an intracellular toxin that depletes host cell energy stores. NADase is dependent on SLO for internalization into epithelial cells, but its mechanism of interaction with the cell surface and details of its translocation mechanism remain unclear. In this study we found that NADase can bind oropharyngeal epithelial cells independently of SLO. This interaction is mediated by both domains of the toxin. We determined by NMR the structure of the translocation domain to be a β-sandwich with a disordered N-terminal region. The folded region of the domain has structural homology to carbohydrate binding modules. We show that excess NADase inhibits SLO-mediated hemolysis and binding to epithelial cells in vitro, suggesting NADase and SLO have shared surface receptors. This effect is abrogated by disruption of a putative carbohydrate binding site on the NADase translocation domain. Our data are consistent with a model whereby interactions of the NADase glycohydrolase domain and translocation domain with SLO and the cell surface increase avidity of NADase binding and facilitate toxin-toxin and toxin-cell surface interactions. IMPORTANCE NADase and streptolysin O (SLO) are secreted toxins important for pathogenesis of group A Streptococcus, the agent of strep throat and severe invasive infections. The two toxins interact in solution and mutually enhance cytotoxic activity. We now find that NADase is capable of binding to the surface of human cells independently of SLO. Structural analysis of the previously uncharacterized translocation domain of NADase suggests that it contains a carbohydrate binding module. The NADase translocation domain and SLO appear to recognize similar glycan structures on the cell surface, which may be one mechanism through which NADase enhances SLO pore-forming activity during infection. Our findings provide new insight into the NADase toxin and its functional interactions with SLO during streptococcal infection.

Dataset Information

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

Publications

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

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets