Structural and functional insight into the interaction of Clostridioides difficile toxin B and FZD 7.
Kinsolving, J., Bous, J., Kozielewicz, P., Kosenina, S., Shekhani, R., Gratz, L., Masuyer, G., Wang, Y., Stenmark, P., Dong, M., Schulte, G.(2024) Cell Rep 43: 113727-113727
- PubMed: 38308843 
- DOI: https://doi.org/10.1016/j.celrep.2024.113727
- Primary Citation of Related Structures:  
8QEN, 8QEO - PubMed Abstract: 
The G protein-coupled receptors of the Frizzled (FZD) family, in particular FZD 1,2,7 , are receptors that are exploited by Clostridioides difficile toxin B (TcdB), the major virulence factor responsible for pathogenesis associated with Clostridioides difficile infection. We employ a live-cell assay examining the affinity between full-length FZDs and TcdB. Moreover, we present cryoelectron microscopy structures of TcdB alone and in complex with full-length FZD 7 , which reveal that large structural rearrangements of the combined repetitive polypeptide domain are required for interaction with FZDs and other TcdB receptors, constituting a first step for receptor recognition. Furthermore, we show that bezlotoxumab, an FDA-approved monoclonal antibody to treat Clostridioides difficile infection, favors the apo-TcdB structure and thus disrupts binding with FZD 7 . The dynamic transition between the two conformations of TcdB also governs the stability of the pore-forming region. Thus, our work provides structural and functional insight into how conformational dynamics of TcdB determine receptor binding.
Organizational Affiliation: 
Karolinska Institutet, Department Physiology & Pharmacology, Sec. Receptor Biology & Signaling, Biomedicum, 17165 Stockholm, Sweden.