Biology subjects

Aktories, K.

Publications and source records attributed to Aktories, K..

3 recordsLinked to original sources

bioRxiv2020

Clostridium difficile binary toxin (CDT) is recognized by the TLR2/6 heterodimer to induce an NF-κB response

Clostridioides difficile infection (CDI) represents a significant burden on the health care system, one that is exacerbated by the emergence of binary toxin (CDT)-producing hypervirulent C. difficile strains. Previous work from our lab has shown that TLR2 recognizes CDT to induce inflammation. Here we explore the interactions of CDT with TLR2 and the impact on host immunity during CDI. We found that the TLR2/6 heterodimer, not TLR2/1, is responsible for CDT recognition, and that gene pathways including NF-{kappa}B and MAPK downstream of TLR2/6 are upregulated in mice with intact TLR2/6 signaling during CDI.

immunology↗

bioRxiv2020

Cryo-EM structure of the fully-loaded asymmetric anthrax lethal toxin in its heptameric pre-pore state

Anthrax toxin is the major virulence factor secreted by Bacillus anthracis, causing high mortality in humans and other mammals. It consists of a membrane translocase, known as protective antigen (PA), that catalyzes the unfolding of its cytotoxic substrates lethal factor (LF) and edema factor (EF), followed by translocation into the host cell. Substrate recruitment to the heptameric PA pre-pore and subsequent translocation, however, are not well understood. Here, we report three high-resolution cryo-EM structures of the fully-loaded anthrax lethal toxin in its heptameric pre-pore state, which differ in the position and conformation of LFs. The structures reveal that three LFs interact with the heptameric PA and upon binding change their conformation to form a continuous chain of head-to-tail interactions. As a result of the underlying symmetry mismatch, one LF binding site in PA remains unoccupied. Whereas one LF directly interacts with a part of PA called -clamp, the others do not interact with this region, indicating an intermediate state between toxin assembly and translocation. Interestingly, the interaction of the N-terminal domain with the -clamp correlates with a higher flexibility in the C-terminal domain of the protein. Based on our data, we propose a model for toxin assembly, in which the order of LF binding determines which factor is translocated first.

molecular biology↗

bioRxiv2019

Photorhabdus Luminescens Toxin complex (TCC) a recombinant injection nano-machine - delivery of recombinant Yersinia enterocolitica YopT

Engineering delivery systems for proteins and peptides into mammalian cells is an ongoing challenge for cell biological studies as well as for therapeutic approaches. Photorhabdus luminescens toxin complex (PTC) is a heterotrimeric protein complex able to deliver diverse protein toxins into mammalian cells. We engineered the syringe like nano-machine for delivery of protein toxins from different species. Additionally, we loaded the highly active copepod luciferase Metridia longa M-Luc7 for accurate quantification of injected molecules. We suggest that besides the size also the charge of the cargo defines the efficiency of packing and transport into mammalian cells. Our data show that the Photorhabdus luminescens toxin complex constitutes a powerful system to inject recombinant proteins, peptides and potentially other molecules like aptamers into mammalian cells. In contrast to other protein transporters based on pore formation, the cargo is protected from degradation. The system opens new perspectives for cell research and pharmacology.

bioengineering↗