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Camelid VHH Antibodies that Neutralize Botulinum Neurotoxin Serotype E Intoxication or Protease Function
Open AccessArticle

Two VHH Antibodies Neutralize Botulinum Neurotoxin E1 by Blocking Its Membrane Translocation in Host Cells

1
Department of Physiology & Biophysics, University of California, Irvine, CA 92617, USA
2
NE-CAT and Department of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Argonne, IL 60439, USA
3
Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA 01536, USA
*
Author to whom correspondence should be addressed.
Toxins 2020, 12(10), 616; https://doi.org/10.3390/toxins12100616
Received: 18 August 2020 / Revised: 16 September 2020 / Accepted: 22 September 2020 / Published: 27 September 2020
(This article belongs to the Special Issue Inhibitors and Countermeasures against Bacterial and Plant Toxins)
Botulinum neurotoxin serotype E (BoNT/E) is one of the major causes of human botulism, which is a life-threatening disease caused by flaccid paralysis of muscles. After receptor-mediated toxin internalization into motor neurons, the translocation domain (HN) of BoNT/E transforms into a protein channel upon vesicle acidification in endosomes and delivers its protease domain (LC) across membrane to enter the neuronal cytosol. It is believed that the rapid onset of BoNT/E intoxication compared to other BoNT serotypes is related to its swift internalization and translocation. We recently identified two neutralizing single-domain camelid antibodies (VHHs) against BoNT/E1 termed JLE-E5 and JLE-E9. Here, we report the crystal structures of these two VHHs bound to the LCHN domain of BoNT/E1. The structures reveal that these VHHs recognize two distinct epitopes that are partially overlapping with the putative transmembrane regions on HN, and therefore could physically block membrane association of BoNT/E1. This is confirmed by our in vitro studies, which show that these VHHs inhibit the structural change of BoNT/E1 at acidic pH and interfere with BoNT/E1 association with lipid vesicles. Therefore, these two VHHs neutralize BoNT/E1 by preventing the transmembrane delivery of LC. Furthermore, structure-based sequence analyses show that the 3-dimensional epitopes of these two VHHs are largely conserved across many BoNT/E subtypes, suggesting a broad-spectrum protection against the BoNT/E family. In summary, this work improves our understanding of the membrane translocation mechanism of BoNT/E and paves the way for developing VHHs as diagnostics or therapeutics for the treatment of BoNT/E intoxication. View Full-Text
Keywords: botulinum neurotoxin; botulism; single-domain antibody; VHH; neutralizing epitope; antitoxin; membrane translocation botulinum neurotoxin; botulism; single-domain antibody; VHH; neutralizing epitope; antitoxin; membrane translocation
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MDPI and ACS Style

Lam, K.-H.; Perry, K.; Shoemaker, C.B.; Jin, R. Two VHH Antibodies Neutralize Botulinum Neurotoxin E1 by Blocking Its Membrane Translocation in Host Cells. Toxins 2020, 12, 616. https://doi.org/10.3390/toxins12100616

AMA Style

Lam K-H, Perry K, Shoemaker CB, Jin R. Two VHH Antibodies Neutralize Botulinum Neurotoxin E1 by Blocking Its Membrane Translocation in Host Cells. Toxins. 2020; 12(10):616. https://doi.org/10.3390/toxins12100616

Chicago/Turabian Style

Lam, Kwok-Ho; Perry, Kay; Shoemaker, Charles B.; Jin, Rongsheng. 2020. "Two VHH Antibodies Neutralize Botulinum Neurotoxin E1 by Blocking Its Membrane Translocation in Host Cells" Toxins 12, no. 10: 616. https://doi.org/10.3390/toxins12100616

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