Download MendeleyA camelid single-domain antibody neutralizes botulinum neurotoxin A by blocking host receptor binding.
Yao, G., Lam, K.H., Weisemann, J., Peng, L., Krez, N., Perry, K., Shoemaker, C.B., Dong, M., Rummel, A., Jin, R.(2017) Sci Rep 7: 7438-7438
- PubMed: 28785006
- DOI: https://doi.org/10.1038/s41598-017-07457-5
- Primary Citation of Related Structures:
5L21 - PubMed Abstract:
Antibody treatment is currently the only available countermeasure for botulism, a fatal illness caused by flaccid paralysis of muscles due to botulinum neurotoxin (BoNT) intoxication. Among the seven major serotypes of BoNT/A-G, BoNT/A poses the most serious threat to humans because of its high potency and long duration of action. Prior to entering neurons and blocking neurotransmitter release, BoNT/A recognizes motoneurons via a dual-receptor binding process in which it engages both the neuron surface polysialoganglioside (PSG) and synaptic vesicle glycoprotein 2 (SV2). Previously, we identified a potent neutralizing antitoxin against BoNT/A1 termed ciA-C2, derived from a camelid heavy-chain-only antibody (VHH). In this study, we demonstrate that ciA-C2 prevents BoNT/A1 intoxication by inhibiting its binding to neuronal receptor SV2. Furthermore, we determined the crystal structure of ciA-C2 in complex with the receptor-binding domain of BoNT/A1 (H C A1) at 1.68 Å resolution. The structure revealed that ciA-C2 partially occupies the SV2-binding site on H C A1, causing direct interference of H C A1 interaction with both the N-glycan and peptide-moiety of SV2. Interestingly, this neutralization mechanism is similar to that of a monoclonal antibody in clinical trials, despite that ciA-C2 is more than 10-times smaller. Taken together, these results enlighten our understanding of BoNT/A1 interactions with its neuronal receptor, and further demonstrate that inhibiting toxin binding to the host receptor is an efficient countermeasure strategy.
Organizational Affiliation:
Department of Physiology and Biophysics, University of California, Irvine, California, USA.
