title: Septins guide microtubule protrusions induced by actin-depolymerizing toxins like Clostridium difficile transferase (CDT).
abstract: Hypervirulent Clostridium difficile strains, which are associated with increased morbidity and mortality, produce the actin-ADP ribosylating toxin Clostridium difficile transferase (CDT). CDT depolymerizes actin, causes formation of microtubule-based protrusions, and increases pathogen adherence. Here, we show that septins (SEPT) are essential for CDT-induced protrusion formation. SEPT2, -6, -7, and -9 accumulate at predetermined protrusion sites and form collar-like structures at the base of protrusions. The septin inhibitor forchlorfenuron or knockdown of septins inhibits protrusion formation. At protrusion sites, septins colocalize with the GTPase Cdc42 (cell division control protein 42) and its effector Borg (binder of Rho GTPases), which act as up-stream regulators of septin polymerization. Precipitation and surface plasmon resonance studies revealed high-affinity binding of septins to the microtubule plus-end tracking protein EB1, thereby guiding incoming microtubules. The data suggest that CDT usurps conserved regulatory principles involved in microtubule-membrane interaction, depending on septins, Cdc42, Borgs, and restructuring of the actin cytoskeleton.
authors.affiliation: Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104 Freiburg, Germany;
authors.forename: Thilo
authors.initials: T
authors.lastname: Nölke
authors.affiliation: Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104 Freiburg, Germany;
authors.forename: Carsten
authors.initials: C
authors.lastname: Schwan
authors.affiliation: Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104 Freiburg, Germany; Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, 79104 Freiburg, Germany; Faculty of Chemistry and Pharmacy, University of Freiburg, 79104 Freiburg, Germany;
authors.forename: Friederike
authors.initials: F
authors.lastname: Lehmann
authors.affiliation: Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany;
authors.forename: Kristine
authors.initials: K
authors.lastname: Østevold
authors.affiliation: Institute of Cell Biology, University of Bern, 3012 Bern, Switzerland;
authors.forename: Olivier
authors.initials: O
authors.lastname: Pertz
authors.affiliation: Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104 Freiburg, Germany; Centre for Biological Signalling Studies (BIOSS), University of Freiburg, 79104 Freiburg, Germany; Freiburg Institute of Advanced Studies (FRIAS), University of Freiburg, 79104 Freiburg, Germany klaus.aktories@pharmakol.uni-freiburg.de.
authors.forename: Klaus
authors.initials: K
authors.lastname: Aktories
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000494:pharmacology*; D018938:Caco-2 Cells; D016360:Clostridioides difficile / Q000201:enzymology*; D004285:Dogs; D020555:GTP-Binding Protein Regulators / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D061985:Madin Darby Canine Kidney Cells; D008810:Mice, Inbred C57BL; D008870:Microtubules / Q000187:drug effects*; D058112:Septins / Q000378:metabolism*; D014166:Transferases / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism
chemical_list: D001427:Bacterial Toxins; D020555:GTP-Binding Protein Regulators; D014166:Transferases; D058112:Septins; D020764:cdc42 GTP-Binding Protein
keywords: Clostridium difficile; actin; bacterial toxin; microtubules; septins