Andreas Pich (Hannover / DE), Theresa Schweitzer (Hannover / DE), Florian Stieglitz (Hannover / DE), Ralf Gerhard (Hannover / DE), Harald Genth (Hannover / DE), Ingo Just (Hannover / DE)
Large clostridial toxins (LCTs) have been identified as primary virulence factors in various animal and human diseases such as C. difficile infection (CDI), wound-associated gas gangrene or toxic shock syndrome. Classification of toxins as LCTs was made basing on a high sequence homology and similar structural set up as well as their ability to induce pronounced changes in cell morphology. The group of LCTs include toxins TcdA and TcdB from Clostridioides difficile, TcsL and TcsH from Paeniclostridium sordellii, TcnA from Clostridium novyi and Clostridium perfringens" TpeL.
Proteome and phosphoproteome responses of C. difficile toxins and C. novyi"s TcnA were analyzed in cell culture to elucidate unknown functions of these pathogens and their toxins. A combinational approach of biochemical analysis and different MS techniques were used to investigate effects of TcdA, TcdB, CDT and TcnA on target cells in vitro. Cell-cell junction, cytoskeleton organization and cell death were found to be toxin-responsive. Toxic effects of TcdA could be traced back to its glucosyltransferase activity while in case of TcdB a catalytically inactive variant also altered the proteome of target cells and induced early cell death. By infection of mice with C. difficile spores various biological processes related to immune response were identified as enriched while metabolic processes were found to be down-regulated.
Utilizing various MS techniques it was possible to illuminate so far unknown effects of C. difficile and its toxins as well as C. novyi"s TcnA on cellular processes of the host.