5VQM

Clostridium difficile TcdB-GTD bound to PA41 Fab

Summary for 5VQM

• Entry DOI: 10.2210/pdb5vqm/pdb
• Descriptor: Toxin B, PA41 FAB LIGHT CHAIN, PA41 FAB HEAVY CHAIN, ... (4 entities in total)
• Functional Keywords: toxin antibody, toxin-immune system complex, toxin/immune system
• Biological source: Peptoclostridium difficile (Clostridium difficile); More
• Total number of polymer chains: 6
• Total formula weight: 223373.91

Authors

Kroh, H.K.,Spiller, B.W.,Lacy, D.B. (deposition date: 2017-05-09, release date: 2017-12-06, Last modification date: 2023-10-04)

Primary citation

Kroh, H.K.,Chandrasekaran, R.,Zhang, Z.,Rosenthal, K.,Woods, R.,Jin, X.,Nyborg, A.C.,Rainey, G.J.,Warrener, P.,Melnyk, R.A.,Spiller, B.W.,Lacy, D.B.
A neutralizing antibody that blocks delivery of the enzymatic cargo of Clostridium difficile toxin TcdB into host cells.
J. Biol. Chem., 293:941-952, 2018

PubMed Abstract: infection is the leading cause of hospital-acquired diarrhea and is mediated by the actions of two toxins, TcdA and TcdB. The toxins perturb host cell function through a multistep process of receptor binding, endocytosis, low pH-induced pore formation, and the translocation and delivery of an N-terminal glucosyltransferase domain that inactivates host GTPases. Infection studies with isogenic strains having defined toxin deletions have established TcdB as an important target for therapeutic development. Monoclonal antibodies that neutralize TcdB function have been shown to protect against infection in animal models and reduce recurrence in humans. Here, we report the mechanism of TcdB neutralization by PA41, a humanized monoclonal antibody capable of neutralizing TcdB from a diverse array of strains. Through a combination of structural, biochemical, and cell functional studies, involving X-ray crystallography and EM, we show that PA41 recognizes a single, highly conserved epitope on the TcdB glucosyltransferase domain and blocks productive translocation and delivery of the enzymatic cargo into the host cell. Our study reveals a unique mechanism of toxin neutralization by a monoclonal antibody, which involves targeting a process that is conserved across the large clostridial glucosylating toxins. The PA41 antibody described here provides a valuable tool for dissecting the mechanism of toxin pore formation and translocation across the endosomal membrane.

PubMed: 29180448
DOI: 10.1074/jbc.M117.813428

Experimental method

X-RAY DIFFRACTION (2.79 Å)