Interaction of Clostridioides difficile Toxin B and the endolysosomal transport and autophagic flux

• Applicant: Professor Dr. Ralf Gerhard
• Subject Area: Toxicology, Laboratory Medicine
• Term: since 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 387231528

As a cellular uptake mechanism, endocytosis is a very dynamic and tightly controlled process. It is of particular importance in the uptake of bacteria and bacterial pathogenicity factors, which must be efficiently subjected to lysosomal degradation. We have been able to show that Clostridioides difficile TcdB in particular, but also all other large clostridial glycosyltransferases, is able to disrupt endosome flux and lysosome function. The molecular mechanism is postulated to be a disruption of membrane integrity caused by integration of the toxin into the endosomal membrane. The recruitment of CHMP4B, a protein of the repair complex ESCRT, confirms this. As a result of the disruption of membrane integrity, enlarged endolysosomes accumulate in the centre of the cell. The planned project aims to verify a disruption of endolysosomal vesicle transport as a mechanism of toxin-mediated reduced lysosome function. The focus is on the low-molecular Rab GTPases that regulate vesicle transport and whose altered activity status should provide information about the dynamics of endolysosome maturation. Active, GTP-bound Rab/ will be determined via the binding domain of the effector protein RILP. Using Rab5/7-inhibiting substances, the influence of inhibition of these GTPases will be examined both during lysosome maturation and regarding the lysosomal degradation of toxins.

• DFG Programme: Research Grants