Hsp70 facilitates trans-membrane transport of bacterial ADP-ribosylating toxins into the cytosol of mammalian cells

Katharina Ernst (1) , Johannes Schmid (1) , Matthias Beck (1) , Marlen Hägele (1) , Meike Hohwieler (1) , Patricia Hauff (1) , Anna Katharina Ückert (1) , Anna Anastasia (1) , Michael Fauler (1) , Thomas Jank (2) , Klaus Aktories (2) , Michel Popoff (3) , Cordelia Schiene-Fischer (4) , Alexander Kleger (1) , Martin Müller (1) , Manfred Frick (1) , Holger Barth (1)

1 Universität Ulm - Ulm University [Ulm, Allemagne]
2 University of Freiburg [Freiburg]
3 CNR - Centre National de Référence des Bactéries Anaérobies et Botulisme - National Reference Center Anaerobic Bacteria and Botulism
4 Martin-Luther-University Halle-Wittenberg

Binary enterotoxins Clostridium (C.) botulinum C2 toxin, C. perfringens iota toxin and C. difficile toxin CDT are composed of a transport (B) and a separate non-linked enzyme (A) component. Their B-components mediate endocytic uptake into mammalian cells and subsequently transport of the A-components from acidic endosomes into the cytosol, where the latter ADP-ribosylate G-actin resulting in cell rounding and cell death causing clinical symptoms. Protein folding enzymes, including Hsp90 and peptidyl-prolyl cis/trans isomerases facilitate transport of the A-components across endosomal membranes. Here, we identified Hsp70 as a novel host cell factor specifically interacting with A-components of C2, iota and CDT toxins to facilitate their transport into the cell cytosol. Pharmacological Hsp70-inhibition specifically prevented pH-dependent trans-membrane transport of A-components into the cytosol thereby protecting living cells and stem cell-derived human miniguts from intoxication. Thus, Hsp70-inhibition might lead to development of novel therapeutic strategies to treat diseases associated with bacterial ADP-ribosylating toxins.

Domaines: Toxicologie

Katharina Ernst, Johannes Schmid, Matthias Beck, Marlen Hägele, Meike Hohwieler, et al.. Hsp70 facilitates trans-membrane transport of bacterial ADP-ribosylating toxins into the cytosol of mammalian cells. Scientific Reports, 2017, 7 (1), pp.2724. ⟨10.1038/s41598-017-02882-y⟩. ⟨pasteur-01820496⟩