title: The catalytic domains of Clostridium sordellii lethal toxin and related large clostridial glucosylating toxins specifically recognize the negatively charged phospholipids phosphatidylserine and phosphatidic acid.
abstract: Clostridium sordellii lethal toxin (TcsL) is a potent virulence factor belonging to the large clostridial glucosylating toxin family. TcsL enters target cells via receptor-mediated endocytosis and delivers the N-terminal catalytic domain (TcsL-cat) into the cytosol upon an autoproteolytic process. TcsL-cat inactivates small GTPases including Rac and Ras by glucosylation with uridine-diphosphate (UDP)-glucose as cofactor leading to drastic changes in cytoskeleton and cell viability. TcsL-cat was found to preferentially bind to phosphatidylserine (PS)-containing membranes and to increase the glucosylation of Rac anchored to lipid membrane. We here report binding affinity measurements of TcsL-cat for brain PS-containing membranes by surface plasmon resonance and enzyme-linked immunosorbent assay (ELISA). In addition, TcsL-cat bound to phosphatidic acid (PA) and, to a lesser extent, to other anionic lipids, but not to neutral lipids, sphingolipids or sterol. We further show that the lipid unsaturation status influenced TcsL-cat binding to phospholipids, PS with unsaturated acyl chains and PA with saturated acyl chains being the preferred bindingsubstrates. Phospholipid binding site is localized at the N-terminal four helical bundle structure (1-93 domain). However, TcsL-1-93 bound to a broad range of substrates, whereas TcsL-cat, which is the active domain physiologically delivered into the cytosol, selectively bound to PS and PA. Similar findings were observed with the other large clostridial glucosylating toxins from C. difficile, C. novyi and C. perfringens.
authors.affiliation: Unité des Bactéries anaérobies et Toxines, Institut Pasteur, Paris, France.
authors.forename: Carolina
authors.initials: C
authors.lastname: Varela Chavez
authors.affiliation: Plateforme de Biophysique Moléculaire, Institut Pasteur, Paris, France.
authors.forename: Sylviane
authors.initials: S
authors.lastname: Hoos
authors.affiliation: Unité des Bactéries anaérobies et Toxines, Institut Pasteur, Paris, France.
authors.forename: Georges Michel
authors.initials: GM
authors.lastname: Haustant
authors.affiliation: Unité de Biochimie des Interactions Macromoléculaires, Institut Pasteur, Paris, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Chenal
authors.affiliation: Plateforme de Biophysique Moléculaire, Institut Pasteur, Paris, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: England
authors.affiliation: Unité de Bioinformatique Structurale, Institut Pasteur, Paris, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Blondel
authors.affiliation: Unité des Bactéries anaérobies et Toxines, Institut Pasteur, Paris, France.
authors.forename: Serge
authors.initials: S
authors.lastname: Pauillac
authors.affiliation: Unité de Bioinformatique Structurale, Institut Pasteur, Paris, France.|Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA.
authors.forename: D Borden
authors.initials: DB
authors.lastname: Lacy
authors.affiliation: Unité des Bactéries anaérobies et Toxines, Institut Pasteur, Paris, France.
authors.forename: Michel Robert
authors.initials: MR
authors.lastname: Popoff
mesh_terms: D000838:Anions / Q000378:metabolism; D001427:Bacterial Toxins / Q000378:metabolism*; D001665:Binding Sites; D020134:Catalytic Domain; D002462:Cell Membrane / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D010712:Phosphatidic Acids / Q000378:metabolism*; D010718:Phosphatidylserines / Q000378:metabolism*; D011485:Protein Binding; D020349:Surface Plasmon Resonance
chemical_list: D000838:Anions; D001427:Bacterial Toxins; D010712:Phosphatidic Acids; D010718:Phosphatidylserines; C072292:lethal toxin LT, Clostridium sordellii