title: The Translocation Domain of Botulinum Neurotoxin A Moderates the Propensity of the Catalytic Domain to Interact with Membranes at Acidic pH.
abstract: Botulinum neurotoxin A (BoNT/A) is composed of three domains: a catalytic domain (LC), a translocation domain (HN) and a receptor-binding domain (HC). Like most bacterial toxins BoNT/A is an amphitropic protein, produced in a soluble form that is able to interact, penetrate and/or cross a membrane to achieve its toxic function. During intoxication BoNT/A is internalized by the cell by receptor-mediated endocytosis. Then, LC crosses the membrane of the endocytic compartment and reaches the cytosol. This translocation is initiated by the low pH found in this compartment. It has been suggested that LC passes in an unfolded state through a transmembrane passage formed by HN. We report here that acidification induces no major conformational change in either secondary or tertiary structures of LC and HN of BoNT/A in solution. GdnHCl-induced denaturation experiments showed that the stability of LC and HN increases as pH drops, and that HN further stabilizes LC. Unexpectedly we found that LC has a high propensity to interact with and permeabilize anionic lipid bilayers upon acidification without the help of HN. This property is downplayed when LC is linked to HN. HN thus acts as a chaperone for LC by enhancing its stability but also as a moderator of the membrane interaction of LC.
authors.affiliation: CEA, iBiTec-S/SIMOPRO, CEA-Saclay, Paris Saclay University, LabEx LERMIT, F-91191 Gif-sur-Yvette, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Araye
authors.affiliation: CEA, iBiTec-S/SIMOPRO, CEA-Saclay, Paris Saclay University, LabEx LERMIT, F-91191 Gif-sur-Yvette, France.
authors.forename: Amélie
authors.initials: A
authors.lastname: Goudet
authors.affiliation: CEA, iBiTec-S/SIMOPRO, CEA-Saclay, Paris Saclay University, LabEx LERMIT, F-91191 Gif-sur-Yvette, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Barbier
authors.affiliation: CEA, iBiTec-S/SIMOPRO, CEA-Saclay, Paris Saclay University, LabEx LERMIT, F-91191 Gif-sur-Yvette, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Pichard
authors.affiliation: Institut Pasteur, Proteopole, Plateforme de Biophysique des Macromolécules et de leurs Interactions (PFBMI), 25-28 rue du Dr Roux, F-75724 Paris cedex 15, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Baron
authors.affiliation: Institut Pasteur, Proteopole, Plateforme de Biophysique des Macromolécules et de leurs Interactions (PFBMI), 25-28 rue du Dr Roux, F-75724 Paris cedex 15, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: England
authors.affiliation: Synchrotron Soleil, BP 48, F-91192 Gif-sur-Yvette Cedex, France.
authors.forename: Javier
authors.initials: J
authors.lastname: Pérez
authors.affiliation: CEA, iBiTec-S/LBSR, CEA-Saclay, F-91191 Gif-sur-Yvette, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Zinn-Justin
authors.affiliation: Institut Pasteur, Unité de Biochimie des Interactions Macromoléculaires, UMR 3528, 25-28 rue du Dr Roux, F-75724 Paris cedex 15, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Chenal
authors.affiliation: CEA, iBiTec-S/SIMOPRO, CEA-Saclay, Paris Saclay University, LabEx LERMIT, F-91191 Gif-sur-Yvette, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Gillet
mesh_terms: D019274:Botulinum Toxins, Type A / Q000378:metabolism*; D020134:Catalytic Domain / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D008051:Lipid Bilayers / Q000378:metabolism; D008566:Membranes / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism; D009498:Neurotoxins / Q000378:metabolism; D010539:Permeability; D011485:Protein Binding / Q000502:physiology; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology*
chemical_list: D008051:Lipid Bilayers; D018832:Molecular Chaperones; D009498:Neurotoxins; D019274:Botulinum Toxins, Type A