Cellular uptake of the Rho-activating toxins CNF1 and CNFY and of further deamidases

• Applicant: Professorin Dr. Gudula Schmidt
• Subject Area: Pharmacology ; Cell Biology
• Term: from 2014 to 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 261620687

• Final Report Year: 2025

Final Report Abstract

My group studies bacterial protein toxins for many years. Specifically, we analyze toxins which modify and activate Rho GTPases. Rho proteins belong to the Ras superfamily of small GTPases. The toxins we study are deamidases: (Cytotoxic Necrotizing Factors 1, 2, 3 und CNFY as well as CNFS) produced by pathogenen Escherichia coli, Yersinia pseudotuberculosis and Salmonella enterica and the Dermonecrotic toxin (DNT) from Bordetella. They modify a specific amino acid of Rho GTPases (Gln 61/63). A further deamidase modifies Galpha subunits of heterotrimeric G proteins: Pasteurella multocida toxin PMT. Aim of this proposal was to characterize the mechanism of uptake of these toxins. We studied the uptake mechanism and identified two specific toxin receptors on the cell surface, which is the Lutheran basal cell adhesion molecule (Lu/BCAM) for CNF1 and the LDL receptor related protein 1 (LRP1) for PMT. The exact knowledge about the function of bacterial toxins in basic research enables us to modulate the toxins properties for their use as cell biological tools and potentially as therapeutic agent. How important the knowledge about cellular binding and uptake of toxins is may be reflected by our registration for a patent of a fusion of chlorotoxin with CNF1. This modified toxin prolongs the life of glioblastoma-bearing mice.

Publications

• Electrophysiology of glioma: a Rho GTPase-activating protein reduces tumor growth and spares neuron structure and function. Neuro-Oncology, 18(12), 1634-1643.
  Vannini, Eleonora; Olimpico, Francesco; Middei, Silvia; Ammassari-Teule, Martine; de Graaf, Erik L.; McDonnell, Liam; Schmidt, Gudula; Fabbri, Alessia; Fiorentini, Carla; Baroncelli, Laura; Costa, Mario & Caleo, Matteo
  
• High Affinity Binding of Escherichia coli Cytotoxic Necrotizing Factor 1 (CNF1) to Lu/BCAM Adhesion Glycoprotein. Toxins, 10(1), 3.
  Reppin, Franziska; Cochet, Sylvie; El Nemer, Wassim; Fritz, Günter & Schmidt, Gudula
  
• Involvement of Osteocytes in the Action of Pasteurella multocida Toxin. Toxins, 10(8), 328.
  Heni, Hannah; Ebner, Julia K.; Schmidt, Gudula; Aktories, Klaus & Orth, Joachim H. C.
  
• RhoA/C inhibits proliferation by inducing the synthesis of GPRC5A. Scientific Reports, 10(1).
  Richter, Lukas; Oberländer, Viktoria & Schmidt, Gudula
  
• CTX-CNF1 Recombinant Protein Selectively Targets Glioma Cells In Vivo. Toxins, 13(3), 194.
  Vannini, Eleonora; Mori, Elisabetta; Tantillo, Elena; Schmidt, Gudula; Caleo, Matteo & Costa, Mario
  
• Yersinia pseudotuberculosis cytotoxic necrotizing factor interacts with glycosaminoglycans. The FASEB Journal, 35(7).
  Kowarschik, Stefanie; Schöllkopf, Julian; Müller, Thomas; Tian, Songhai; Knerr, Julian; Bakker, Hans; Rein, Stephan; Dong, Min; Weber, Stefan; Grosse, Robert & Schmidt, Gudula
  
• Genome wide CRISPR screen for Pasteurella multocida toxin (PMT) binding proteins reveals LDL Receptor Related Protein 1 (LRP1) as crucial cellular receptor. PLOS Pathogens, 18(12), e1010781.
  Schoellkopf, Julian; Mueller, Thomas; Hippchen, Lena; Mueller, Teresa; Reuten, Raphael; Backofen, Rolf; Orth, Joachim & Schmidt, Gudula