Nölke Thilo, Schwan Carsten, Lehmann Friederike, Østevold Kristine, Pertz Olivier, Aktories Klaus
Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104 Freiburg, Germany;
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;
Proc Natl Acad Sci U S A. 2016 Jul 12;113(28):7870-5. doi: 10.1073/pnas.1522717113. Epub 2016 Jun 23.
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.
高毒力艰难梭菌菌株与发病率和死亡率增加相关，可产生肌动蛋白-ADP核糖基化毒素艰难梭菌转移酶（CDT）。CDT使肌动蛋白解聚，导致基于微管的突起形成，并增加病原体的黏附。在此，我们表明，septin蛋白（SEPT）对于CDT诱导的突起形成至关重要。SEPT2、-6、-7和-9在预定的突起部位聚集，并在突起基部形成衣领状结构。septin抑制剂氯吡脲或septin蛋白敲低可抑制突起形成。在突起部位，septin蛋白与GTP酶Cdc42（细胞分裂控制蛋白42）及其效应器Borg（Rho GTP酶结合蛋白）共定位，它们作为septin蛋白聚合的上游调节因子。沉淀和表面等离子体共振研究揭示了septin蛋白与微管正端追踪蛋白EB1的高亲和力结合，从而引导进入的微管。数据表明，CDT利用了参与微管-膜相互作用的保守调节机制，这依赖于septin蛋白、Cdc42、Borg蛋白以及肌动蛋白细胞骨架的重塑。
