Structural and functional insight into the interaction of Clostridioides difficile toxin B and FZD7
Julia Kinsolving,
Julien Bous,
Pawel Kozielewicz,
Sara Košenina,
Rawan Shekhani,
Lukas Grätz,
Geoffrey Masuyer,
Yuankai Wang,
Pål Stenmark,
Min Dong,
Gunnar Schulte
Affiliations
Julia Kinsolving
Karolinska Institutet, Department Physiology & Pharmacology, Sec. Receptor Biology & Signaling, Biomedicum, 17165 Stockholm, Sweden
Julien Bous
Karolinska Institutet, Department Physiology & Pharmacology, Sec. Receptor Biology & Signaling, Biomedicum, 17165 Stockholm, Sweden
Pawel Kozielewicz
Karolinska Institutet, Department Physiology & Pharmacology, Sec. Receptor Biology & Signaling, Biomedicum, 17165 Stockholm, Sweden
Sara Košenina
Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
Rawan Shekhani
Karolinska Institutet, Department Physiology & Pharmacology, Sec. Receptor Biology & Signaling, Biomedicum, 17165 Stockholm, Sweden
Lukas Grätz
Karolinska Institutet, Department Physiology & Pharmacology, Sec. Receptor Biology & Signaling, Biomedicum, 17165 Stockholm, Sweden
Geoffrey Masuyer
Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
Yuankai Wang
Department of Urology, Boston Children’s Hospital, Department of Surgery and Department of Microbiology, Harvard Medical School, Boston, MA, USA
Pål Stenmark
Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
Min Dong
Department of Urology, Boston Children’s Hospital, Department of Surgery and Department of Microbiology, Harvard Medical School, Boston, MA, USA
Gunnar Schulte
Karolinska Institutet, Department Physiology & Pharmacology, Sec. Receptor Biology & Signaling, Biomedicum, 17165 Stockholm, Sweden; Corresponding author
Summary: The G protein-coupled receptors of the Frizzled (FZD) family, in particular FZD1,2,7, 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 FZD7, 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 FZD7. 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.
