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Joensuu M, Syed P, Saber SH, Lanoue V, Wallis TP, Rae J, Blum A, Gormal RS, Small C, Sanders S, Jiang A, Mahrhold S, Krez N, Cousin MA, Cooper‐White R, Cooper‐White JJ, Collins BM, Parton RG, Balistreri G, Rummel A, Meunier FA. Presynaptic targeting of botulinum neurotoxin type A requires a tripartite PSG-Syt1-SV2 plasma membrane nanocluster for synaptic vesicle entry. EMBO J 2023; 42:e112095. [PMID: 37226896 PMCID: PMC10308369 DOI: 10.15252/embj.2022112095] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 04/18/2023] [Accepted: 04/28/2023] [Indexed: 05/26/2023] Open
Abstract
The unique nerve terminal targeting of botulinum neurotoxin type A (BoNT/A) is due to its capacity to bind two receptors on the neuronal plasma membrane: polysialoganglioside (PSG) and synaptic vesicle glycoprotein 2 (SV2). Whether and how PSGs and SV2 may coordinate other proteins for BoNT/A recruitment and internalization remains unknown. Here, we demonstrate that the targeted endocytosis of BoNT/A into synaptic vesicles (SVs) requires a tripartite surface nanocluster. Live-cell super-resolution imaging and electron microscopy of catalytically inactivated BoNT/A wildtype and receptor-binding-deficient mutants in cultured hippocampal neurons demonstrated that BoNT/A must bind coincidentally to a PSG and SV2 to target synaptic vesicles. We reveal that BoNT/A simultaneously interacts with a preassembled PSG-synaptotagmin-1 (Syt1) complex and SV2 on the neuronal plasma membrane, facilitating Syt1-SV2 nanoclustering that controls endocytic sorting of the toxin into synaptic vesicles. Syt1 CRISPRi knockdown suppressed BoNT/A- and BoNT/E-induced neurointoxication as quantified by SNAP-25 cleavage, suggesting that this tripartite nanocluster may be a unifying entry point for selected botulinum neurotoxins that hijack this for synaptic vesicle targeting.
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Affiliation(s)
- Merja Joensuu
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
- Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
- Australian Institute for Bioengineering and NanotechnologyThe University of QueenslandBrisbaneQLDAustralia
| | - Parnayan Syed
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
- Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
| | - Saber H Saber
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
- Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
- Australian Institute for Bioengineering and NanotechnologyThe University of QueenslandBrisbaneQLDAustralia
| | - Vanessa Lanoue
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
- Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
| | - Tristan P Wallis
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
- Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
| | - James Rae
- Institute for Molecular BioscienceThe University of QueenslandBrisbaneQLDAustralia
| | - Ailisa Blum
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
- Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
| | - Rachel S Gormal
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
- Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
| | - Christopher Small
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
- Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
| | - Shanley Sanders
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
- Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
| | - Anmin Jiang
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
- Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
| | - Stefan Mahrhold
- Institut für ToxikologieMedizinische Hochschule HannoverHannoverGermany
| | - Nadja Krez
- Institut für ToxikologieMedizinische Hochschule HannoverHannoverGermany
| | - Michael A Cousin
- Centre for Discovery Brain Sciences, Hugh Robson BuildingUniversity of EdinburghEdinburghUK
- Muir Maxwell Epilepsy CentreUniversity of EdinburghEdinburghUK
- Simons Initiative for the Developing BrainUniversity of EdinburghEdinburghUK
| | - Ruby Cooper‐White
- Australian Institute for Bioengineering and NanotechnologyThe University of QueenslandBrisbaneQLDAustralia
- School of Chemical EngineeringThe University of QueenslandBrisbaneQLDAustralia
| | - Justin J Cooper‐White
- Australian Institute for Bioengineering and NanotechnologyThe University of QueenslandBrisbaneQLDAustralia
- School of Chemical EngineeringThe University of QueenslandBrisbaneQLDAustralia
- UQ Centre for Stem Cell Ageing and Regenerative EngineeringThe University of QueenslandBrisbaneQLDAustralia
| | - Brett M Collins
- Institute for Molecular BioscienceThe University of QueenslandBrisbaneQLDAustralia
| | - Robert G Parton
- Institute for Molecular BioscienceThe University of QueenslandBrisbaneQLDAustralia
- Centre for Microscopy and MicroanalysisThe University of QueenslandBrisbaneQLDAustralia
| | - Giuseppe Balistreri
- Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
- Department of Virology, Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Andreas Rummel
- Institut für ToxikologieMedizinische Hochschule HannoverHannoverGermany
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
- Queensland Brain InstituteThe University of QueenslandBrisbaneQLDAustralia
- School of Biomedical SciencesThe University of QueenslandBrisbaneQLDAustralia
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Cottone G, Chiodo L, Maragliano L, Popoff MR, Rasetti-Escargueil C, Lemichez E, Malliavin TE. In Silico Conformational Features of Botulinum Toxins A1 and E1 According to Intraluminal Acidification. Toxins (Basel) 2022; 14:toxins14090644. [PMID: 36136581 PMCID: PMC9500700 DOI: 10.3390/toxins14090644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 08/13/2022] [Accepted: 09/10/2022] [Indexed: 11/16/2022] Open
Abstract
Although botulinum neurotoxins (BoNTs) are among the most toxic compounds found in nature, their molecular mechanism of action is far from being elucidated. A key event is the conformational transition due to acidification of the interior of synaptic vesicles, leading to translocation of the BoNT catalytic domain into the neuronal cytosol. To investigate these conformational variations, homology modeling and atomistic simulations are combined to explore the internal dynamics of the sub-types BoNT/A1 (the most-used sub-type in medical applications) and BoNT/E1 (the most kinetically efficient sub-type). This first simulation study of di-chain BoNTs in closed and open states considers the effects of both neutral and acidic pH. The conformational mobility is driven by domain displacements of the ganglioside-binding site in the receptor binding domain, the translocation domain (HCNT) switch, and the belt α-helix, which present multiple conformations, depending on the primary sequence and the pH. Fluctuations of the belt α-helix are observed for closed conformations of the toxins and at acidic pH, while patches of more solvent-accessible residues appear under the same conditions in the core translocation domain HCNT. These findings suggest that, during translocation, the higher mobility of the belt could be transmitted to HCNT, leading to the favorable interaction of HCNT residues with the non-polar membrane environment.
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Affiliation(s)
- Grazia Cottone
- Department of Physics and Chemistry Emilio Segré, University of Palermo, Viale delle Scienze, 90128 Palermo, Italy
| | - Letizia Chiodo
- Department of Engineering, University Campus Bio-Medico of Rome, Via Á. del Portillo 21, 00128 Rome, Italy
| | - Luca Maragliano
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona, Italy
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Michel-Robert Popoff
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Inserm U1306, Unité des Toxines Bactériennes, 75015 Paris, France
| | - Christine Rasetti-Escargueil
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Inserm U1306, Unité des Toxines Bactériennes, 75015 Paris, France
| | - Emmanuel Lemichez
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Inserm U1306, Unité des Toxines Bactériennes, 75015 Paris, France
- Correspondence: (E.L.); (T.E.M.)
| | - Thérèse E. Malliavin
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Unité de Bioinformatique Structurale, 75015 Paris, France
- Laboratoire de Physique et Chimie Théoriques (LPCT), CNRS UMR7019, University of Lorraine, 54506 Vandoeuvre-lès-Nancy, France
- Laboratoire International Associé, CNRS and University of Illinois at Urbana-Champaign, 54506 Vandoeuvre-lès-Nancy, France
- Correspondence: (E.L.); (T.E.M.)
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Fabris F, Šoštarić P, Matak I, Binz T, Toffan A, Simonato M, Montecucco C, Pirazzini M, Rossetto O. Detection of VAMP Proteolysis by Tetanus and Botulinum Neurotoxin Type B In Vivo with a Cleavage-Specific Antibody. Int J Mol Sci 2022; 23:ijms23084355. [PMID: 35457172 PMCID: PMC9024618 DOI: 10.3390/ijms23084355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 04/08/2022] [Accepted: 04/12/2022] [Indexed: 11/17/2022] Open
Abstract
Tetanus and Botulinum type B neurotoxins are bacterial metalloproteases that specifically cleave the vesicle-associated membrane protein VAMP at an identical peptide bond, resulting in inhibition of neuroexocytosis. The minute amounts of these neurotoxins commonly used in experimental animals are not detectable, nor is detection of their VAMP substrate sensitive enough. The immune detection of the cleaved substrate is much more sensitive, as we have previously shown for botulinum neurotoxin type A. Here, we describe the production in rabbit of a polyclonal antibody raised versus a peptide encompassing the 13 residues C-terminal with respect to the neurotoxin cleavage site. The antibody was affinity purified and found to recognize, with high specificity and selectivity, the novel N-terminus of VAMP that becomes exposed after cleavage by tetanus toxin and botulinum toxin type B. This antibody recognizes the neoepitope not only in native and denatured VAMP but also in cultured neurons and in neurons in vivo in neurotoxin-treated mice or rats, suggesting the great potential of this novel tool to elucidate tetanus and botulinum B toxin activity in vivo.
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Affiliation(s)
- Federico Fabris
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy; (F.F.); (C.M.)
| | - Petra Šoštarić
- Department of Pharmacology, School of Medicine, University of Zagreb, Šalata 11, 10000 Zagreb, Croatia; (P.Š.); (I.M.)
| | - Ivica Matak
- Department of Pharmacology, School of Medicine, University of Zagreb, Šalata 11, 10000 Zagreb, Croatia; (P.Š.); (I.M.)
| | - Thomas Binz
- Institute of Cellular Biochemistry, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany;
| | - Anna Toffan
- Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell’Università 10, 35020 Legnaro, Italy;
| | - Morena Simonato
- Institute of Neuroscience, Italian Research Council, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy;
| | - Cesare Montecucco
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy; (F.F.); (C.M.)
- Institute of Neuroscience, Italian Research Council, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy;
| | - Marco Pirazzini
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy; (F.F.); (C.M.)
- Interdepartmental Research Center of Myology CIR-Myo, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy
- Correspondence: (M.P.); (O.R.)
| | - Ornella Rossetto
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy; (F.F.); (C.M.)
- Institute of Neuroscience, Italian Research Council, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy;
- Interdepartmental Research Center of Myology CIR-Myo, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy
- Correspondence: (M.P.); (O.R.)
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Near-Infrared Transflectance Spectroscopy Discriminates Solutions Containing Two Commercial Formulations of Botulinum Toxin Type A Diluted at Recommended Volumes for Clinical Reconstitution. BIOSENSORS 2022; 12:bios12040216. [PMID: 35448275 PMCID: PMC9032888 DOI: 10.3390/bios12040216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/01/2022] [Accepted: 04/04/2022] [Indexed: 11/16/2022]
Abstract
Botulinum neurotoxin type A (BoNT-A) is the active substance in pharmaceutical preparations widely used worldwide for the highly effective treatment of various disorders. Among the three commercial formulations of BoNT-A currently available in Italy for neurological indications, abobotulinum A toxin (Dysport®, Ipsen SpA, Milano, Italy) and incobotulinum A toxin (Xeomin®, Merz Pharma Italia srl, Milano, Italy) differ in the content of neurotoxin, non-toxic protein, and excipients. Clinical applications of BoNT-A adopt extremely diluted solutions (10−6 mg/mL) for injection in the target body district. Near-infrared spectroscopy (NIRS) and chemometrics allow rapid, non-invasive, and non-destructive methods for qualitative and quantitative analysis. No data are available to date on the chemometric analysis of the spectral fingerprints acquired from the diluted commercial formulations of BoNT-A. In this proof-of-concept study, we tested whether NIRS can categorize solutions of incobotulinum A toxin (lacking non-toxic proteins) and abobotulinum A toxin (containing non-toxic proteins). Distinct excipients in the two formulations were also analyzed. We acquired transmittance spectra in the visible and short-wave infrared regions (350–2500 nm) by an ASD FieldSpec 4™ Standard-Res Spectrophotoradiometer, using a submerged dip probe designed to read spectra in transflectance mode from liquid samples. After preliminary spectra pre-processing, principal component analysis was applied to characterize the spectral features of the two BoNT-A solutions and those of the various excipients diluted according to clinical standards. Partial least squares-discriminant analysis was used to implement a classification model able to discriminate the BoNT-A solutions and excipients. NIRS distinguished solutions containing distinct BoNT-A commercial formulations (abobotulinum A toxin vs. incobotulinum A toxin) diluted at recommended volumes for clinical reconstitution, distinct proteins (HSA vs. incobotulinum A toxin), very diluted solutions of simple sugars (lactose vs. sucrose), and saline or water. Predictive models of botulinum toxin formulations were also performed with the highest precision and accuracy.
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Feng X, Xiong D, Li J, Xiao L, Xie W, Qiu Y. Direct Inhibition of Microglia Activation by Pretreatment With Botulinum Neurotoxin A for the Prevention of Neuropathic Pain. Front Neurosci 2021; 15:760403. [PMID: 34949981 PMCID: PMC8688716 DOI: 10.3389/fnins.2021.760403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 11/08/2021] [Indexed: 11/24/2022] Open
Abstract
Peripheral injection of botulinum neurotoxin A (BoNT/A) has been demonstrated to have a long-term analgesic effect in treating neuropathic pain. Around peripheral nerves, BoNT/A is taken up by primary afferent neurons and inhibits neuropeptide release. Moreover, BoNT/A could also be retrogradely transported to the spinal cord. Recent studies have suggested that BoNT/A could attenuates neuropathic pain by inhibiting the activation of spinal glial cells. However, it remains unclear whether BoNT/A directly interacts with these glial cells or via their interaction with neurons. Our aim here is to determine the direct effect of BoNT/A on primary microglia and astrocytes. We show that BoNT/A pretreatment significantly inhibits lipopolysaccharide (LPS) -induced activation and pro-inflammatory cytokine release in primary microglia (1 U/mL BoNT/A in medium), while it has no effect on the activation of astrocytes (2 U/mL BoNT/A in medium). Moreover, a single intrathecal pre-administration of a low dose of BoNT/A (1 U/kg) significantly prohibited the partial sciatic nerve ligation (PSNL)- induced upregulation of pro-inflammatory cytokines in both the spinal cord dorsal horn and dorsal root ganglions (DRGs), which in turn prevented the PSNL-induced mechanical allodynia and thermal hyperalgesia. In conclusion, our results indicate that BoNT/A pretreatment prevents PSNL-induced neuropathic pain by direct inhibition of spinal microglia activation.
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Affiliation(s)
- Xiaona Feng
- Research Center for Neural Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.,School of Medicine, Southern University of Science and Technology, Shenzhen, China
| | - Donglin Xiong
- Shenzhen Municipal Key Laboratory for Pain Medicine, Department of Pain Medicine, Shenzhen Nanshan People's Hospital, The 6th Affiliated Hospital of Shenzhen University Health Science Center, Shenzhen, China
| | - Jie Li
- Department of Anesthesiology, Shenzhen Second People's Hospital, Shenzhen, China
| | - Lizu Xiao
- Shenzhen Municipal Key Laboratory for Pain Medicine, Department of Pain Medicine, Shenzhen Nanshan People's Hospital, The 6th Affiliated Hospital of Shenzhen University Health Science Center, Shenzhen, China
| | - Weijiao Xie
- Research Center for Neural Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.,Shenzhen Municipal Key Laboratory for Pain Medicine, Department of Pain Medicine, Shenzhen Nanshan People's Hospital, The 6th Affiliated Hospital of Shenzhen University Health Science Center, Shenzhen, China
| | - Yunhai Qiu
- Research Center for Neural Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.,Shenzhen Municipal Key Laboratory for Pain Medicine, Department of Pain Medicine, Shenzhen Nanshan People's Hospital, The 6th Affiliated Hospital of Shenzhen University Health Science Center, Shenzhen, China
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Mechanism of Ganglioside Receptor Recognition by Botulinum Neurotoxin Serotype E. Int J Mol Sci 2021; 22:ijms22158315. [PMID: 34361086 PMCID: PMC8346984 DOI: 10.3390/ijms22158315] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 01/10/2023] Open
Abstract
The botulinum neurotoxins are potent molecules that are not only responsible for the lethal paralytic disease botulism, but have also been harnessed for therapeutic uses in the treatment of an increasing number of chronic neurological and neuromuscular disorders, in addition to cosmetic applications. The toxins act at the cholinergic nerve terminals thanks to an efficient and specific mechanism of cell recognition which is based on a dual receptor system that involves gangliosides and protein receptors. Binding to surface-anchored gangliosides is the first essential step in this process. Here, we determined the X-ray crystal structure of the binding domain of BoNT/E, a toxin of clinical interest, in complex with its GD1a oligosaccharide receptor. Beyond confirmation of the conserved ganglioside binding site, we identified key interacting residues that are unique to BoNT/E and a significant rearrangement of loop 1228–1237 upon carbohydrate binding. These observations were also supported by thermodynamic measurements of the binding reaction and assessment of ganglioside selectivity by immobilised-receptor binding assays. These results provide a structural basis to understand the specificity of BoNT/E for complex gangliosides.
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Brier S, Rasetti-Escargueil C, Wijkhuisen A, Simon S, Marechal M, Lemichez E, Popoff MR. Characterization of a highly neutralizing single monoclonal antibody to botulinum neurotoxin type A. FASEB J 2021; 35:e21540. [PMID: 33817838 DOI: 10.1096/fj.202002492r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 02/25/2021] [Accepted: 03/03/2021] [Indexed: 01/15/2023]
Abstract
Compared to conventional antisera strategies, monoclonal antibodies (mAbs) represent an alternative and safer way to treat botulism, a fatal flaccid paralysis due to botulinum neurotoxins (BoNTs). In addition, mAbs offer the advantage to be produced in a reproducible manner. We previously identified a unique and potent mouse mAb (TA12) targeting BoNT/A1 with high affinity and neutralizing activity. In this study, we characterized the molecular basis of TA12 neutralization by combining Hydrogen/Deuterium eXchange Mass Spectrometry (HDX-MS) with site-directed mutagenesis and functional studies. We found that TA12 recognizes a conformational epitope located at the interface between the HCN and HCC subdomains of the BoNT/A1 receptor-binding domain (HC ). The TA12-binding interface shares common structural features with the ciA-C2 VHH epitope and lies on the face opposite recognized by ciA-C2- and the CR1/CR2-neutralizing mAbs. The single substitution of N1006 was sufficient to affect TA12 binding to HC confirming the position of the epitope. We further uncovered that the TA12 epitope overlaps with the BoNT/A1-binding site for both the neuronal cell surface receptor synaptic vesicle glycoprotein 2 isoform C (SV2C) and the GT1b ganglioside. Hence, TA12 potently blocks the entry of BoNT/A1 into neurons by interfering simultaneously with the binding of SV2C and to a lower extent GT1b. Our study reveals the unique neutralization mechanism of TA12 and emphasizes on the potential of using single mAbs for the treatment of botulism type A.
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Affiliation(s)
- Sébastien Brier
- Biological NMR Technological Platform, Institut Pasteur, CNRS UMR3528, Paris, France
| | | | - Anne Wijkhuisen
- Département Médicaments et Technologies pour la santé, Université Paris-Saclay, CEA, INRAE, Gif-sur-Yvette, France
| | - Stéphanie Simon
- Département Médicaments et Technologies pour la santé, Université Paris-Saclay, CEA, INRAE, Gif-sur-Yvette, France
| | - Maud Marechal
- Institut Pasteur, Unité des Toxines Bactériennes, UMR CNRS 2001, Paris, France
| | - Emmanuel Lemichez
- Institut Pasteur, Unité des Toxines Bactériennes, UMR CNRS 2001, Paris, France
| | - Michel R Popoff
- Institut Pasteur, Unité des Toxines Bactériennes, UMR CNRS 2001, Paris, France
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Candalija A, Scior T, Rackwitz HR, Ruiz-Castelan JE, Martinez-Laguna Y, Aguilera J. Interaction between a Novel Oligopeptide Fragment of the Human Neurotrophin Receptor TrkB Ectodomain D5 and the C-Terminal Fragment of Tetanus Neurotoxin. Molecules 2021; 26:molecules26133988. [PMID: 34208805 PMCID: PMC8272241 DOI: 10.3390/molecules26133988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/20/2021] [Accepted: 05/26/2021] [Indexed: 11/16/2022] Open
Abstract
This article presents experimental evidence and computed molecular models of a potential interaction between receptor domain D5 of TrkB with the carboxyl-terminal domain of tetanus neurotoxin (Hc-TeNT). Computational simulations of a novel small cyclic oligopeptide are designed, synthesized, and tested for possible tetanus neurotoxin-D5 interaction. A hot spot of this protein-protein interaction is identified in analogy to the hitherto known crystal structures of the complex between neurotrophin and D5. Hc-TeNT activates the neurotrophin receptors, as well as its downstream signaling pathways, inducing neuroprotection in different stress cellular models. Based on these premises, we propose the Trk receptor family as potential proteic affinity receptors for TeNT. In vitro, Hc-TeNT binds to a synthetic TrkB-derived peptide and acts similar to an agonist ligand for TrkB, resulting in phosphorylation of the receptor. These properties are weakened by the mutagenesis of three residues of the predicted interaction region in Hc-TeNT. It also competes with Brain-derived neurotrophic factor, a native binder to human TrkB, for the binding to neural membranes, and for uptake in TrkB-positive vesicles. In addition, both molecules are located together in vivo at neuromuscular junctions and in motor neurons.
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Affiliation(s)
- Ana Candalija
- Molecular Biology Department, Institut de Neruociènces and Biochemistry, Medicine Faculty, Universitat Autònoma de Barcelona (UAB), 08193 Barcelona, Spain; (A.C.); (J.A.)
| | - Thomas Scior
- Faculty of Chemical Sciences, BUAP, Puebla 72000, Mexico; (J.E.R.-C.); (Y.M.-L.)
- Correspondence: or ; Tel.: +52-222-229-5500 (ext. 7529)
| | - Hans-Richard Rackwitz
- Peptide Specialities Laboratory, Im Neuenheimer Feld, Univerisity Campus, 69120 Heidelberg, Germany;
| | | | | | - José Aguilera
- Molecular Biology Department, Institut de Neruociènces and Biochemistry, Medicine Faculty, Universitat Autònoma de Barcelona (UAB), 08193 Barcelona, Spain; (A.C.); (J.A.)
- Center for Biomedical Research Network on Neurodegenerative Diseases (CIBERNED), 08193 Cerdanyola del Vallès, Spain
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Characterization of clostridium botulinum neurotoxin serotype A (BoNT/A) and fibroblast growth factor receptor interactions using novel receptor dimerization assay. Sci Rep 2021; 11:7832. [PMID: 33837264 PMCID: PMC8035261 DOI: 10.1038/s41598-021-87331-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 03/24/2021] [Indexed: 01/03/2023] Open
Abstract
Clostridium botulinum neurotoxin serotype A (BoNT/A) is a potent neurotoxin that serves as an effective therapeutic for several neuromuscular disorders via induction of temporary muscular paralysis. Specific binding and internalization of BoNT/A into neuronal cells is mediated by its binding domain (HC/A), which binds to gangliosides, including GT1b, and protein cell surface receptors, including SV2. Previously, recombinant HC/A was also shown to bind to FGFR3. As FGFR dimerization is an indirect measure of ligand-receptor binding, an FCS & TIRF receptor dimerization assay was developed to measure rHC/A-induced dimerization of fluorescently tagged FGFR subtypes (FGFR1-3) in cells. rHC/A dimerized FGFR subtypes in the rank order FGFR3c (EC50 ≈ 27 nM) > FGFR2b (EC50 ≈ 70 nM) > FGFR1c (EC50 ≈ 163 nM); rHC/A dimerized FGFR3c with similar potency as the native FGFR3c ligand, FGF9 (EC50 ≈ 18 nM). Mutating the ganglioside binding site in HC/A, or removal of GT1b from the media, resulted in decreased dimerization. Interestingly, reduced dimerization was also observed with an SV2 mutant variant of HC/A. Overall, the results suggest that the FCS & TIRF receptor dimerization assay can assess FGFR dimerization with known and novel ligands and support a model wherein HC/A, either directly or indirectly, interacts with FGFRs and induces receptor dimerization.
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Sikorra S, Donald S, Elliott M, Schwede S, Coker SF, Kupinski AP, Tripathi V, Foster K, Beard M, Binz T. Engineering an Effective Human SNAP-23 Cleaving Botulinum Neurotoxin A Variant. Toxins (Basel) 2020; 12:toxins12120804. [PMID: 33352834 PMCID: PMC7766560 DOI: 10.3390/toxins12120804] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 12/11/2020] [Accepted: 12/13/2020] [Indexed: 12/13/2022] Open
Abstract
Botulinum neurotoxin (BoNT) serotype A inhibits neurotransmitter release by cleaving SNAP-25 and represents an established pharmaceutical for treating medical conditions caused by hyperactivity of cholinergic nerves. Oversecretion from non-neuronal cells is often also the cause of diseases. Notably, excessive release of inflammatory messengers is thought to contribute to diseases such as chronic obstructive pulmonary disease, asthma, diabetes etc. The expansion of its application to these medical conditions is prevented because the major non-neuronal SNAP-25 isoform responsible for exocytosis, SNAP-23, is, in humans, virtually resistant to BoNT/A. Based on previous structural data and mutagenesis studies of SNAP-23 we optimized substrate binding pockets of the enzymatic domain for interaction with SNAP-23. Systematic mutagenesis and rational design yielded the mutations E148Y, K166F, S254A, and G305D, each of which individually increased the activity of LC/A against SNAP-23 between 3- to 23-fold. The assembled quadruple mutant showed approximately 2000-fold increased catalytic activity against human SNAP-23 in in vitro cleavage assays. A comparable increase in activity was recorded for the full-length BoNT/A quadruple mutant tested in cultivated primary neurons transduced with a fluorescently tagged-SNAP-23 encoding gene. Equipped with a suitable targeting domain this quadruple mutant promises to complete successfully tests in cells of the immune system.
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Affiliation(s)
- Stefan Sikorra
- Institut für Zellbiochemie, OE 4310, Medizinische Hochschule Hannover, 30623 Hannover, Germany; (S.S.); (S.S.)
| | - Sarah Donald
- Ipsen Bioinnovation, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK; (S.D.); (M.E.); (S.-F.C.); (A.P.K.); (V.T.); (K.F.)
| | - Mark Elliott
- Ipsen Bioinnovation, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK; (S.D.); (M.E.); (S.-F.C.); (A.P.K.); (V.T.); (K.F.)
| | - Susan Schwede
- Institut für Zellbiochemie, OE 4310, Medizinische Hochschule Hannover, 30623 Hannover, Germany; (S.S.); (S.S.)
| | - Shu-Fen Coker
- Ipsen Bioinnovation, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK; (S.D.); (M.E.); (S.-F.C.); (A.P.K.); (V.T.); (K.F.)
| | - Adam P. Kupinski
- Ipsen Bioinnovation, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK; (S.D.); (M.E.); (S.-F.C.); (A.P.K.); (V.T.); (K.F.)
| | - Vineeta Tripathi
- Ipsen Bioinnovation, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK; (S.D.); (M.E.); (S.-F.C.); (A.P.K.); (V.T.); (K.F.)
| | - Keith Foster
- Ipsen Bioinnovation, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK; (S.D.); (M.E.); (S.-F.C.); (A.P.K.); (V.T.); (K.F.)
| | - Matthew Beard
- Ipsen Bioinnovation, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK; (S.D.); (M.E.); (S.-F.C.); (A.P.K.); (V.T.); (K.F.)
- Correspondence: (M.B.); (T.B.); Tel.: +44(0)7850-910340 (M.B.); +49(0)511-532-2859 (T.B.)
| | - Thomas Binz
- Institut für Zellbiochemie, OE 4310, Medizinische Hochschule Hannover, 30623 Hannover, Germany; (S.S.); (S.S.)
- Correspondence: (M.B.); (T.B.); Tel.: +44(0)7850-910340 (M.B.); +49(0)511-532-2859 (T.B.)
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11
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The 25 kDa H CN Domain of Clostridial Neurotoxins Is Indispensable for Their Neurotoxicity. Toxins (Basel) 2020; 12:toxins12120743. [PMID: 33255952 PMCID: PMC7760224 DOI: 10.3390/toxins12120743] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 11/13/2020] [Accepted: 11/20/2020] [Indexed: 11/17/2022] Open
Abstract
The extraordinarily potent clostridial neurotoxins (CNTs) comprise tetanus neurotoxin (TeNT) and the seven established botulinum neurotoxin serotypes (BoNT/A-G). They are composed of four structurally independent domains: the roles of the catalytically active light chain, the translocation domain HN, and the C-terminal receptor binding domain HCC are largely resolved, but that of the HCN domain sandwiched between HN and HCC has remained unclear. Here, mutants of BoNT/A, BoNT/B, and TeNT were generated by deleting their HCN domains or swapping HCN domains between each other. Both deletion and replacement of TeNT HCN domain by HCNA and HCNB reduced the biological activity similarly, by ~95%, whereas BoNT/A and B deletion mutants displayed >500-fold reduced activity in the mouse phrenic nerve hemidiaphragm assay. Swapping HCN domains between BoNT/A and B hardly impaired their biological activity, but substitution with HCNT did. Binding assays revealed that in the absence of HCN, not all receptor binding sites are equally well accessible. In conclusion, the presence of HCN is vital for CNTs to exert their neurotoxicity. Although structurally similar, the HCN domain of TeNT cannot equally substitute those of BoNT and vice versa, leaving the possibility that HCNT plays a different role in the intoxication mechanism of TeNT.
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12
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Davies JR, Masuyer G, Stenmark P. Structural and Biochemical Characterization of Botulinum Neurotoxin Subtype B2 Binding to Its Receptors. Toxins (Basel) 2020; 12:toxins12090603. [PMID: 32957706 PMCID: PMC7551386 DOI: 10.3390/toxins12090603] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/14/2020] [Accepted: 09/16/2020] [Indexed: 12/31/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) can be used therapeutically to treat a wide range of neuromuscular and neurological conditions. A collection of natural BoNT variants exists which can be classified into serologically distinct serotypes (BoNT/B), and further divided into subtypes (BoNT/B1, B2, …). BoNT subtypes share a high degree of sequence identity within the same serotype yet can display large variation in toxicity. One such example is BoNT/B2, which was isolated from Clostridium botulinum strain 111 in a clinical case of botulism, and presents a 10-fold lower toxicity than BoNT/B1. In an effort to understand the molecular mechanisms behind this difference in potency, we here present the crystal structures of BoNT/B2 in complex with the ganglioside receptor GD1a, and with the human synaptotagmin I protein receptor. We show, using receptor-binding assays, that BoNT/B2 has a slightly higher affinity for GD1a than BoNT/B1, and confirm its considerably weaker affinity for its protein receptors. Although the overall receptor-binding mechanism is conserved for both receptors, structural analysis suggests the lower affinity of BoNT/B2 is the result of key substitutions, where hydrophobic interactions important for synaptotagmin-binding are replaced by polar residues. This study provides a template to drive the development of future BoNT therapeutic molecules centered on assessing the natural subtype variations in receptor-binding that appears to be one of the principal stages driving toxicity.
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Affiliation(s)
- Jonathan R. Davies
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden;
| | - Geoffrey Masuyer
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden;
- Department of Pharmacy and Pharmacology, Centre for Therapeutic Innovation, University of Bath, Bath BA2 7AY, UK
- Correspondence: (G.M.); (P.S.)
| | - Pål Stenmark
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden;
- Department of Experimental Medical Science, Lund University, SE-221 00 Lund, Sweden
- Correspondence: (G.M.); (P.S.)
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13
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Yin L, Masuyer G, Zhang S, Zhang J, Miyashita SI, Burgin D, Lovelock L, Coker SF, Fu TM, Stenmark P, Dong M. Characterization of a membrane binding loop leads to engineering botulinum neurotoxin B with improved therapeutic efficacy. PLoS Biol 2020; 18:e3000618. [PMID: 32182233 PMCID: PMC7077807 DOI: 10.1371/journal.pbio.3000618] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 02/12/2020] [Indexed: 11/25/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are a family of bacterial toxins with seven major serotypes (BoNT/A–G). The ability of these toxins to target and bind to motor nerve terminals is a key factor determining their potency and efficacy. Among these toxins, BoNT/B is one of the two types approved for medical and cosmetic uses. Besides binding to well-established receptors, an extended loop in the C-terminal receptor-binding domain (HC) of BoNT/B (HC/B) has been proposed to also contribute to toxin binding to neurons by interacting with lipid membranes (termed lipid-binding loop [LBL]). Analogous loops exist in the HCs of BoNT/C, D, G, and a chimeric toxin DC. However, it has been challenging to detect and characterize binding of LBLs to lipid membranes. Here, using the nanodisc system and biolayer interferometry assays, we find that HC/DC, C, and G, but not HC/B and HC/D, are capable of binding to receptor-free lipids directly, with HC/DC having the highest level of binding. Mutagenesis studies demonstrate the critical role of consecutive aromatic residues at the tip of the LBL for binding of HC/DC to lipid membranes. Taking advantage of this insight, we then create a “gain-of-function” mutant HC/B by replacing two nonaromatic residues at the tip of its LBL with tryptophan. Cocrystallization studies confirm that these two tryptophan residues do not alter the structure of HC/B or the interactions with its receptors. Such a mutated HC/B gains the ability to bind receptor-free lipid membranes and shows enhanced binding to cultured neurons. Finally, full-length BoNT/B containing two tryptophan mutations in its LBL, together with two additional mutations (E1191M/S1199Y) that increase binding to human receptors, is produced and evaluated in mice in vivo using Digit Abduction Score assays. This mutant toxin shows enhanced efficacy in paralyzing local muscles at the injection site and lower systemic diffusion, thus extending both safety range and duration of paralysis compared with the control BoNT/B. These findings establish a mechanistic understanding of LBL–lipid interactions and create a modified BoNT/B with improved therapeutic efficacy. Botulinum neurotoxins are a family of bacterial toxins, some of which are approved for medical and cosmetic uses. This study shows that introducing aromatic residues to a lipid binding loop improved therapeutic efficacy of botulinum neurotoxin B by enhancing its ability to bind to lipid membranes at motor nerve terminals.
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Affiliation(s)
- Linxiang Yin
- Department of Urology, Boston Children’s Hospital, Department of Microbiology and Department of Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Geoffrey Masuyer
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Sicai Zhang
- Department of Urology, Boston Children’s Hospital, Department of Microbiology and Department of Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jie Zhang
- Department of Urology, Boston Children’s Hospital, Department of Microbiology and Department of Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Shin-Ichiro Miyashita
- Department of Urology, Boston Children’s Hospital, Department of Microbiology and Department of Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | | | | | | | - Tian-min Fu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, Massachusetts, United States of America
| | - Pål Stenmark
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
- Department of Experimental Medical Science, Lund University, Lund, Sweden
- * E-mail: (PS); (MD)
| | - Min Dong
- Department of Urology, Boston Children’s Hospital, Department of Microbiology and Department of Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (PS); (MD)
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14
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Poulain B, Lemichez E, Popoff MR. Neuronal selectivity of botulinum neurotoxins. Toxicon 2020; 178:20-32. [PMID: 32094099 DOI: 10.1016/j.toxicon.2020.02.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 02/03/2020] [Accepted: 02/10/2020] [Indexed: 12/12/2022]
Abstract
Botulinum neurotoxins (BoNTs) are highly potent toxins responsible for a severe disease, called botulism. They are also efficient therapeutic tools with an increasing number of indications ranging from neuromuscular dysfunction to hypersecretion syndrome, pain release, depression as well as cosmetic application. BoNTs are known to mainly target the motor-neurons terminals and to induce flaccid paralysis. BoNTs recognize a specific double receptor on neuronal cells consisting of gangliosides and synaptic vesicle protein, SV2 or synaptotagmin. Using cultured neuronal cells, BoNTs have been established blocking the release of a wide variety of neurotransmitters. However, BoNTs are more potent in motor-neurons than in the other neuronal cell types. In in vivo models, BoNT/A impairs the cholinergic neuronal transmission at the motor-neurons but also at neurons controlling secretions and smooth muscle neurons, and blocks several neuronal pathways including excitatory, inhibitory, and sensitive neurons. However, only a few reports investigated the neuronal selectivity of BoNTs in vivo. In the intestinal wall, BoNT/A and BoNT/B target mainly the cholinergic neurons and to a lower extent the other non-cholinergic neurons including serotonergic, glutamatergic, GABAergic, and VIP-neurons. The in vivo effects induced by BoNTs on the non-cholinergic neurons remain to be precisely investigated. We report here a literature review of the neuronal selectivity of BoNTs.
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Affiliation(s)
- Bernard Poulain
- Université de Strasbourg, CNRS, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
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15
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Gregory KS, Liu SM, Acharya KR. Crystal structure of botulinum neurotoxin subtype A3 cell binding domain in complex with GD1a co-receptor ganglioside. FEBS Open Bio 2020; 10:298-305. [PMID: 31945264 PMCID: PMC7050238 DOI: 10.1002/2211-5463.12790] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/07/2020] [Accepted: 01/10/2020] [Indexed: 01/20/2023] Open
Abstract
Botulinum neurotoxins (BoNTs) are one of the most toxic proteins known to humans. Their molecular structure is comprised of three essential domains—a cell binding domain (HC), translocation domain and catalytic domain (light chain) . The HC domain facilitates the highly specific binding of BoNTs to the neuronal membrane via a dual‐receptor complex involving a protein receptor and a ganglioside. Variation in activity/toxicity across subtypes of serotype A has been attributed to changes in protein and ganglioside interactions, and their implications are important in the design of novel BoNT‐based therapeutics. Here, we present the structure of BoNT/A3 cell binding domain (HC/A3) in complex with the ganglioside GD1a at 1.75 Å resolution. The structure revealed that six residues interact with the three outermost monosaccharides of GD1a through several key hydrogen bonding interactions. A detailed comparison of structures of HC/A3 with HC/A1 revealed subtle conformational differences at the ganglioside binding site upon carbohydrate binding.
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Affiliation(s)
- Kyle S Gregory
- Department of Biology and Biochemistry, Claverton Down, University of Bath, UK
| | | | - K Ravi Acharya
- Department of Biology and Biochemistry, Claverton Down, University of Bath, UK
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16
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Contreras E, Masuyer G, Qureshi N, Chawla S, Dhillon HS, Lee HL, Chen J, Stenmark P, Gill SS. A neurotoxin that specifically targets Anopheles mosquitoes. Nat Commun 2019; 10:2869. [PMID: 31253776 PMCID: PMC6599013 DOI: 10.1038/s41467-019-10732-w] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 05/23/2019] [Indexed: 11/24/2022] Open
Abstract
Clostridial neurotoxins, including tetanus and botulinum neurotoxins, generally target vertebrates. We show here that this family of toxins has a much broader host spectrum, by identifying PMP1, a clostridial-like neurotoxin that selectively targets anopheline mosquitoes. Isolation of PMP1 from Paraclostridium bifermentans strains collected in anopheline endemic areas on two continents indicates it is widely distributed. The toxin likely evolved from an ancestral form that targets the nervous system of similar organisms, using a common mechanism that disrupts SNARE-mediated exocytosis. It cleaves the mosquito syntaxin and employs a unique receptor recognition strategy. Our research has an important impact on the study of the evolution of clostridial neurotoxins and provides the basis for the use of P. bifermentans strains and PMP1 as innovative, environmentally friendly approaches to reduce malaria through anopheline control. So far identified clostridial neurotoxins target vertebrates. Here, Contreras et al. isolate the clostridial-like neurotoxin PMP1 from Paraclostridium bifermentans strains and show that it selectively targets anopheline mosquitoes by targeting mosquito syntaxin.
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Affiliation(s)
- Estefania Contreras
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA
| | - Geoffrey Masuyer
- Department of Biochemistry and Biophysics, Stockholm University, 106 91, Stockholm, Sweden
| | - Nadia Qureshi
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA
| | - Swati Chawla
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA
| | - Harpal S Dhillon
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA
| | - Han Lim Lee
- Unit of Medical Entomology, Institute for Medical Research, Jalan Pahang, 50588, Kuala Lumpur, Malaysia
| | - Jianwu Chen
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA
| | - Pål Stenmark
- Department of Biochemistry and Biophysics, Stockholm University, 106 91, Stockholm, Sweden. .,Department of Experimental Medical Science, Lund University, Lund, 22100, Sweden.
| | - Sarjeet S Gill
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, 92521, USA.
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17
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Abstract
Botulinum neurotoxins (BoNTs) are a family of bacterial protein toxins produced by various Clostridium species. They are traditionally classified into seven major serotypes (BoNT/A-G). Recent progress in sequencing microbial genomes has led to an ever-growing number of subtypes, chimeric toxins, BoNT-like toxins, and remotely related BoNT homologs, constituting an expanding BoNT superfamily. Recent structural studies of BoNTs, BoNT progenitor toxin complexes, tetanus neurotoxin (TeNT), toxin-receptor complexes, and toxin-substrate complexes have provided mechanistic understandings of toxin functions and the molecular basis for their variations. The growing BoNT superfamily of toxins present a natural repertoire that can be explored to develop novel therapeutic toxins, and the structural understanding of their variations provides a knowledge basis for engineering toxins to improve therapeutic efficacy and expand their clinical applications.
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Affiliation(s)
- Min Dong
- Department of Urology, Boston Children's Hospital, Boston, MA, USA.
- Department of Microbiology, Harvard Medical School, Boston, MA, USA.
- Department of Surgery, Harvard Medical School, Boston, MA, USA.
| | - Pål Stenmark
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
- Department of Experimental Medical Science, Lund University, Lund, Sweden.
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18
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Abstract
Botulinum neurotoxins (BoNTs) and tetanus neurotoxin (TeNT) are the most potent toxins known and cause botulism and tetanus, respectively. BoNTs are also widely utilized as therapeutic toxins. They contain three functional domains responsible for receptor-binding, membrane translocation, and proteolytic cleavage of host proteins required for synaptic vesicle exocytosis. These toxins also have distinct features: BoNTs exist within a progenitor toxin complex (PTC), which protects the toxin and facilitates its absorption in the gastrointestinal tract, whereas TeNT is uniquely transported retrogradely within motor neurons. Our increasing knowledge of these toxins has allowed the development of engineered toxins for medical uses. The discovery of new BoNTs and BoNT-like proteins provides additional tools to understand the evolution of the toxins and to engineer toxin-based therapeutics. This review summarizes the progress on our understanding of BoNTs and TeNT, focusing on the PTC, receptor recognition, new BoNT-like toxins, and therapeutic toxin engineering.
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Affiliation(s)
- Min Dong
- Department of Urology, Boston Children's Hospital, Boston, Massachusetts 02115, USA; .,Department of Microbiology and Immunobiology and Department of Surgery, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Geoffrey Masuyer
- Department of Biochemistry and Biophysics, Stockholm University, 106 91 Stockholm, Sweden;
| | - Pål Stenmark
- Department of Biochemistry and Biophysics, Stockholm University, 106 91 Stockholm, Sweden; .,Department of Experimental Medical Science, Lund University, 221 00 Lund, Sweden
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19
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Davies JR, Liu SM, Acharya KR. Variations in the Botulinum Neurotoxin Binding Domain and the Potential for Novel Therapeutics. Toxins (Basel) 2018; 10:toxins10100421. [PMID: 30347838 PMCID: PMC6215321 DOI: 10.3390/toxins10100421] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 10/11/2018] [Accepted: 10/18/2018] [Indexed: 01/23/2023] Open
Abstract
Botulinum neurotoxins (BoNTs) are categorised into immunologically distinct serotypes BoNT/A to /G). Each serotype can also be further divided into subtypes based on differences in amino acid sequence. BoNTs are ~150 kDa proteins comprised of three major functional domains: an N-terminal zinc metalloprotease light chain (LC), a translocation domain (HN), and a binding domain (HC). The HC is responsible for targeting the BoNT to the neuronal cell membrane, and each serotype has evolved to bind via different mechanisms to different target receptors. Most structural characterisations to date have focussed on the first identified subtype within each serotype (e.g., BoNT/A1). Subtype differences within BoNT serotypes can affect intoxication, displaying different botulism symptoms in vivo, and less emphasis has been placed on investigating these variants. This review outlines the receptors for each BoNT serotype and describes the basis for the highly specific targeting of neuronal cell membranes. Understanding receptor binding is of vital importance, not only for the generation of novel therapeutics but also for understanding how best to protect from intoxication.
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Affiliation(s)
- Jonathan R Davies
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK.
| | - Sai Man Liu
- Ipsen Bioinnovation Limited, Abingdon OX14 4RY, UK.
| | - K Ravi Acharya
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK.
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20
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Variability of Botulinum Toxins: Challenges and Opportunities for the Future. Toxins (Basel) 2018; 10:toxins10090374. [PMID: 30217070 PMCID: PMC6162648 DOI: 10.3390/toxins10090374] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 09/03/2018] [Accepted: 09/08/2018] [Indexed: 12/31/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are the most potent known toxins, and are therefore classified as extremely harmful biological weapons. However, BoNTs are therapeutic drugs that are widely used and have an increasing number of applications. BoNTs show a high diversity and are divided into multiple types and subtypes. Better understanding of the activity at the molecular and clinical levels of the natural BoNT variants as well as the development of BoNT-based chimeric molecules opens the door to novel medical applications such as silencing the sensory neurons at targeted areas and dermal restoration. This short review is focused on BoNTs’ variability and the opportunities or challenges posed for future clinical applications.
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21
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Fonfria E, Elliott M, Beard M, Chaddock JA, Krupp J. Engineering Botulinum Toxins to Improve and Expand Targeting and SNARE Cleavage Activity. Toxins (Basel) 2018; 10:toxins10070278. [PMID: 29973505 PMCID: PMC6071219 DOI: 10.3390/toxins10070278] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 06/29/2018] [Accepted: 07/01/2018] [Indexed: 12/14/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are highly successful protein therapeutics. Over 40 naturally occurring BoNTs have been described thus far and, of those, only 2 are commercially available for clinical use. Different members of the BoNT family present different biological properties but share a similar multi-domain structure at the molecular level. In nature, BoNTs are encoded by DNA in producing clostridial bacteria and, as such, are amenable to recombinant production through insertion of the coding DNA into other bacterial species. This, in turn, creates possibilities for protein engineering. Here, we review the production of BoNTs by the natural host and also recombinant production approaches utilised in the field. Applications of recombinant BoNT-production include the generation of BoNT-derived domain fragments, the creation of novel BoNTs with improved performance and enhanced therapeutic potential, as well as the advancement of BoNT vaccines. In this article, we discuss site directed mutagenesis, used to affect the biological properties of BoNTs, including approaches to alter their binding to neurons and to alter the specificity and kinetics of substrate cleavage. We also discuss the target secretion inhibitor (TSI) platform, in which the neuronal binding domain of BoNTs is substituted with an alternative cellular ligand to re-target the toxins to non-neuronal systems. Understanding and harnessing the potential of the biological diversity of natural BoNTs, together with the ability to engineer novel mutations and further changes to the protein structure, will provide the basis for increasing the scope of future BoNT-based therapeutics.
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Affiliation(s)
- Elena Fonfria
- Ipsen Bioinnovation, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK.
| | - Mark Elliott
- Ipsen Bioinnovation, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK.
| | - Matthew Beard
- Ipsen Bioinnovation, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK.
| | - John A Chaddock
- Ipsen Bioinnovation, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK.
| | - Johannes Krupp
- Ipsen Innovation, 5 Avenue du Canada, 91940 Les Ulis, France.
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22
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Stern D, Weisemann J, Le Blanc A, von Berg L, Mahrhold S, Piesker J, Laue M, Luppa PB, Dorner MB, Dorner BG, Rummel A. A lipid-binding loop of botulinum neurotoxin serotypes B, DC and G is an essential feature to confer their exquisite potency. PLoS Pathog 2018; 14:e1007048. [PMID: 29718991 PMCID: PMC5951583 DOI: 10.1371/journal.ppat.1007048] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 05/14/2018] [Accepted: 04/19/2018] [Indexed: 11/21/2022] Open
Abstract
The exceptional toxicity of botulinum neurotoxins (BoNTs) is mediated by high avidity binding to complex polysialogangliosides and intraluminal segments of synaptic vesicle proteins embedded in the presynaptic membrane. One peculiarity is an exposed hydrophobic loop in the toxin’s cell binding domain HC, which is located between the ganglioside- and protein receptor-binding sites, and that is particularly pronounced in the serotypes BoNT/B, DC, and G sharing synaptotagmin as protein receptor. Here, we provide evidence that this HC loop is a critical component of their tripartite receptor recognition complex. Binding to nanodisc-embedded receptors and toxicity were virtually abolished in BoNT mutants lacking residues at the tip of the HC loop. Surface plasmon resonance experiments revealed that only insertion of the HC loop into the lipid-bilayer compensates for the entropic penalty inflicted by the dual-receptor binding. Our results represent a new paradigm of how BoNT/B, DC, and G employ ternary interactions with a protein, ganglioside, and lipids to mediate their extraordinary neurotoxicity. Botulinum neurotoxins are Janus-faced molecules: due to their exquisite toxicity, botulinum neurotoxins are considered as biological weapons, but they are also highly effective medicines for numerous neurological indications. However, what mediates their exquisite toxicity? The exclusive binding to neurons and the subsequent paralysis cuts off the host’s communication networks. The neurospecific binding is ensured by anchoring to two receptor molecules both embedded in the membrane: a complex ganglioside and a synaptic vesicle protein. Here, we reveal a third interaction between a hydrophobic so-called HC loop protruding from the surface of the serotypes BoNT/B, DC, and G into the lipid membrane. Only this HC loop ensures their high-affinity binding to the neuronal receptors also at physiological temperature (37°C). Hereby, BoNT/B, DC, and G prevent untimely dissociation prior to uptake into the neuron. Therefore, our study provides the mechanistic basis for the development of inhibitors to combat botulism, but it also has implications for engineering toxin—membrane interactions yielding optimized BoNT-based therapeutics to treat neuromuscular dysfunctions successfully. Intriguingly, a broadly neutralizing anti-HIV-1 antibody shares a similar strategy, emphasizing the general relevance of our results for host—pathogen interactions.
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Affiliation(s)
- Daniel Stern
- Biological Toxins (ZBS 3), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Berlin, Germany
| | - Jasmin Weisemann
- Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Alexander Le Blanc
- Institute for Clinical Chemistry and Pathobiochemistry, Klinikum rechts der Isar, Technische Universität München, München, Germany
| | - Laura von Berg
- Biological Toxins (ZBS 3), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Berlin, Germany
| | - Stefan Mahrhold
- Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Janett Piesker
- Advanced Light and Electron Microscopy (ZBS 4), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Berlin, Germany
| | - Michael Laue
- Advanced Light and Electron Microscopy (ZBS 4), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Berlin, Germany
| | - Peter B. Luppa
- Institute for Clinical Chemistry and Pathobiochemistry, Klinikum rechts der Isar, Technische Universität München, München, Germany
| | - Martin Bernhard Dorner
- Biological Toxins (ZBS 3), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Berlin, Germany
| | - Brigitte Gertrud Dorner
- Biological Toxins (ZBS 3), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Berlin, Germany
- * E-mail: (BGD); (AR)
| | - Andreas Rummel
- Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover, Germany
- * E-mail: (BGD); (AR)
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23
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Davies JR, Hackett GS, Liu SM, Acharya KR. High resolution crystal structures of the receptor-binding domain of Clostridium botulinum neurotoxin serotypes A and FA. PeerJ 2018; 6:e4552. [PMID: 29576992 PMCID: PMC5866713 DOI: 10.7717/peerj.4552] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 03/08/2018] [Indexed: 01/12/2023] Open
Abstract
The binding specificity of botulinum neurotoxins (BoNTs) is primarily a consequence of their ability to bind to multiple receptors at the same time. BoNTs consist of three distinct domains, a metalloprotease light chain (LC), a translocation domain (HN) and a receptor-binding domain (HC). Here we report the crystal structure of HC/FA, complementing an existing structure through the modelling of a previously unresolved loop which is important for receptor-binding. Our HC/FA structure also contains a previously unidentified disulphide bond, which we have also observed in one of two crystal forms of HC/A1. This may have implications for receptor-binding and future recombinant toxin production.
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Affiliation(s)
- Jonathan R Davies
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | | | - Sai Man Liu
- Ipsen Bioinnovation Limited, Abingdon, United Kingdom
| | - K Ravi Acharya
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
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24
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Yu CH, Song DH, Choi JY, Joe HE, Jeong WH, Hur GH, Shin YK, Jeong ST. A mutated recombinant subunit vaccine protects mice and guinea pigs against botulinum type A intoxication. Hum Vaccin Immunother 2018; 14:329-336. [PMID: 29140753 PMCID: PMC5806659 DOI: 10.1080/21645515.2017.1405201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 10/17/2017] [Accepted: 11/09/2017] [Indexed: 02/08/2023] Open
Abstract
Botulinum neurotoxins (BoNTs) are the most potent toxins to mammals. A toxoid vaccine was previously used for prevention of botulinum intoxication; however, this vaccine is no longer available. Currently, no approved botulinum vaccines are available from the Food and Drug Administration (FDA). Recently, a recombinant host cell receptor-binding subunit created for use as a potential vaccine completed phase 2 clinical trials. The current study designed a vaccine candidate against BoNT type A (BoNT/A) using a structural design. Our vaccine candidate was the BoNT/A heavy chain C-terminal region (HCR) that contained the point mutation BA15 (R1269A) within the ganglioside-binding site. A Biacore affinity test showed that the affinity of BA15 for ganglioside GT1b was 100 times lower than that of the HCR. A SNAP25 cleavage assay revealed that immunized sera blocked SNAP25 cleavage of the BoNT/A toxin via BA15. In an in vivo experiment, mice and guinea pigs immunized with BA15 produced neutralizing antibodies that protected against 3,000 LD50 of BoNT/A. In conclusion, the results of both in vitro and in vivo assays showed that our BA15 vaccine candidate was similar to the recombinant host cell receptor-binding subunit vaccine. The inability of BA15to bind ganglioside shows that BA15 is a potential safe vaccine candidate.
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Affiliation(s)
- Chi Ho Yu
- Agency for Defense Development, Yuseong, Daejeon, Republic of Korea
| | - Dong Hyun Song
- Agency for Defense Development, Yuseong, Daejeon, Republic of Korea
| | - Jun Young Choi
- Abion R&D Institute, Hanhwa Biz-Metro, Guro-gu, Seoul, Republic of Korea
| | - Hae Eun Joe
- Agency for Defense Development, Yuseong, Daejeon, Republic of Korea
| | - Woo Hyeon Jeong
- Agency for Defense Development, Yuseong, Daejeon, Republic of Korea
| | - Gyeung Haeng Hur
- Agency for Defense Development, Yuseong, Daejeon, Republic of Korea
| | - Young Kee Shin
- Department of Pharmacy, College of Pharmacy, Seoul National University, Dajeon, Seoul, Republic of Korea
| | - Seong Tae Jeong
- Agency for Defense Development, Yuseong, Daejeon, Republic of Korea
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25
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Identification of a Botulinum Neurotoxin-like Toxin in a Commensal Strain of Enterococcus faecium. Cell Host Microbe 2018; 23:169-176.e6. [PMID: 29396040 DOI: 10.1016/j.chom.2017.12.018] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/20/2017] [Accepted: 12/14/2017] [Indexed: 12/11/2022]
Abstract
Botulinum neurotoxins (BoNTs), produced by various Clostridium strains, are a family of potent bacterial toxins and potential bioterrorism agents. Here we report that an Enterococcus faecium strain isolated from cow feces carries a BoNT-like toxin, designated BoNT/En. It cleaves both VAMP2 and SNAP-25, proteins that mediate synaptic vesicle exocytosis in neurons, at sites distinct from known BoNT cleavage sites on these two proteins. Comparative genomic analysis determines that the E. faecium strain carrying BoNT/En is a commensal type and that the BoNT/En gene is located within a typical BoNT gene cluster on a 206 kb putatively conjugative plasmid. Although the host species targeted by BoNT/En remains to be determined, these findings establish an extended member of BoNTs and demonstrate the capability of E. faecium, a commensal organism ubiquitous in humans and animals and a leading cause of hospital-acquired multi-drug-resistant (MDR) infections, to horizontally acquire, and possibly disseminate, a unique BoNT gene cluster.
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26
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Przedpelski A, Tepp WH, Zuverink M, Johnson EA, Pellet S, Barbieri JT. Enhancing toxin-based vaccines against botulism. Vaccine 2018; 36:827-832. [PMID: 29307477 DOI: 10.1016/j.vaccine.2017.12.064] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 12/19/2017] [Accepted: 12/20/2017] [Indexed: 01/25/2023]
Abstract
Botulinum neurotoxins (BoNT) are the most toxic proteins for humans. BoNTs are single chain proteins with an N-terminal light chain (LC) and a C-terminal heavy chain (HC). HC comprises a translocation domain (HCN) and a receptor binding domain (HCC). Currently, there are no approved vaccines against botulism. This study tests a recombinant, full-length BoNT/A1 versus LCHCN/A1 and HCC/A1 as vaccine candidates against botulism. Recombinant, full-length BoNT/A1 was detoxified by engineering 3-amino acid mutations (E224A/R363A/Y366F) (M-BoNT/A1) into the LC to eliminate catalytic activity, which reduced toxicity in a mouse model of botulism by >106-fold relative to native BoNT/A1. As a second step to improve vaccine safety, an additional mutation (W1266A) was engineered in the ganglioside binding pocket, resulting in reduced receptor binding, to produce M-BoNT/A1W. M-BoNT/A1W vaccination protected against challenge by 106 LD50 Units of native BoNT/A1, while M-BoNT/A1 or M-BoNT/A1W vaccination equally protected against challenge by native BoNT/A2, a BoNT subtype. Mice vaccinated with M-BoNT/A1W surviving BoNT challenge had dominant antibody responses to the LCHCN domain, but varied antibody responses to HCC. Sera from mice vaccinated with M-BoNT/A1W also neutralized BoNT/A1 action on cultured neuronal cells. The cell- and mouse-based assays measured different BoNT-neutralizing antibodies, where M-BoNT/A1W elicited a strong neutralizing response in both assays. Overall, M-BoNT/A1W, with defects in multiple toxin functions, elicits a potent immune response to BoNT/A challenge as a vaccine strategy against botulism and other toxin-mediated diseases.
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Affiliation(s)
- Amanda Przedpelski
- Medical College of Wisconsin, 8701 W Watertown Plank Rd., Microbiology and Immunology, Milwaukee, WI 53226, United States
| | - William H Tepp
- University of Wisconsin-Madison, 6303 Microbial Sciences Building, 1550 Linden Dr., Madison, WI 53706, United States
| | - Madison Zuverink
- Medical College of Wisconsin, 8701 W Watertown Plank Rd., Microbiology and Immunology, Milwaukee, WI 53226, United States
| | - Eric A Johnson
- University of Wisconsin-Madison, 6303 Microbial Sciences Building, 1550 Linden Dr., Madison, WI 53706, United States
| | - Sabine Pellet
- University of Wisconsin-Madison, 6303 Microbial Sciences Building, 1550 Linden Dr., Madison, WI 53706, United States
| | - Joseph T Barbieri
- Medical College of Wisconsin, 8701 W Watertown Plank Rd., Microbiology and Immunology, Milwaukee, WI 53226, United States.
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27
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Structural basis for the unique ganglioside and cell membrane recognition mechanism of botulinum neurotoxin DC. Nat Commun 2017; 8:1637. [PMID: 29158482 PMCID: PMC5696347 DOI: 10.1038/s41467-017-01534-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 09/25/2017] [Indexed: 12/15/2022] Open
Abstract
Botulinum neurotoxins (BoNTs), the most potent toxins known, are potential bioterrorism agents. It is well established that all seven serotypes of BoNTs (BoNT/A–G) require complex gangliosides as co-receptors. Here, we report that BoNT/DC, a presumed mosaic toxin between BoNT/D and BoNT/C1, binds and enters efficiently into neurons lacking complex gangliosides and shows no reduction in toxicity in mice deficient in complex gangliosides. The co-crystal structure of BoNT/DC with sialyl-Thomsen-Friedenreich antigen (Sialyl-T) suggests that BoNT/DC recognizes only the sialic acid, but not other moieties in gangliosides. Using liposome flotation assays, we demonstrate that an extended loop in BoNT/DC directly interacts with lipid membranes, and the co-occurring sialic acid binding and loop–membrane interactions mediate the recognition of gangliosides in membranes by BoNT/DC. These findings reveal a unique mechanism for cell membrane recognition and demonstrate that BoNT/DC can use a broad range of sialic acid-containing moieties as co-receptors. Botulinum neurotoxins (BoNTs) are thought to require complex gangliosides, a group of glycosphingolipids, as essential co-receptors to target neurons. Here, the authors show that BoNT/DC represents an exception to this rule and that an extended loop in BoNT/DC penetrates directly into neuronal membranes.
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28
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Rust A, Doran C, Hart R, Binz T, Stickings P, Sesardic D, Peden AA, Davletov B. A Cell Line for Detection of Botulinum Neurotoxin Type B. Front Pharmacol 2017; 8:796. [PMID: 29170639 PMCID: PMC5684488 DOI: 10.3389/fphar.2017.00796] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 10/20/2017] [Indexed: 01/29/2023] Open
Abstract
Botulinum neurotoxins (BoNTs) type A and type B are commonly used as biopharmaceutics for neurological diseases, uniquely allowing months-long paralysis of target muscles. Their exquisite neuronal specificity is conferred by a multistep process of binding, internalization, cytosolic escape and cleavage of the neuron-specific proteins, SNAP-25 and vesicle-associated membrane proteins (VAMPs), ultimately to inhibit secretion of neurotransmitters. Currently the mouse lethality bioassay is the only available method for quality control testing of VAMP-cleaving botulinum products. Refined assays for botulinum product testing are urgently needed. Specifically, in vitro replacement assays which can account for all steps of BoNT intoxication are in high demand. Here, we describe a novel SiMa cell-based approach where re-engineering of the VAMP molecule allows detection of all BoNT/B intoxication steps using a luminescent enzymatic reaction with sensitivity comparable to mouse LD50 bioassay. The presented one-step enzyme-linked immunosorbent assay meets 3Rs (replacement, reduction, and refinement of the use of animals) objectives, is user-friendly and will accelerate development of new botulinum drugs. The sensitive enzymatic reporter cell line could also be adapted for the detection of toxin activity during the manufacture of botulinum and tetanus vaccines.
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Affiliation(s)
- Aleksander Rust
- Department of Biomedical Sciences, University of Sheffield, Sheffield, United Kingdom
| | - Ciara Doran
- Department of Biomedical Sciences, University of Sheffield, Sheffield, United Kingdom
| | - Rosalyn Hart
- Department of Biomedical Sciences, University of Sheffield, Sheffield, United Kingdom
| | - Thomas Binz
- Institut für Zellbiochemie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Paul Stickings
- Division of Bacteriology, National Institute for Biological Standards and Control, Medicines and Healthcare Product Regulatory Agency, Potters Bar, United Kingdom
| | - Dorothea Sesardic
- Division of Bacteriology, National Institute for Biological Standards and Control, Medicines and Healthcare Product Regulatory Agency, Potters Bar, United Kingdom
| | - Andrew A. Peden
- Department of Biomedical Sciences, University of Sheffield, Sheffield, United Kingdom
| | - Bazbek Davletov
- Department of Biomedical Sciences, University of Sheffield, Sheffield, United Kingdom
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29
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Fujinaga Y, Popoff MR. Translocation and dissemination of botulinum neurotoxin from the intestinal tract. Toxicon 2017; 147:13-18. [PMID: 29074396 DOI: 10.1016/j.toxicon.2017.10.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 10/16/2017] [Accepted: 10/22/2017] [Indexed: 12/19/2022]
Abstract
Botulinum neurotoxins (BoNTs) are potent toxins which induce flaccid paralysis by inhibiting the release of acetylcholine at the neuromuscular junctions. They associate with non-toxic proteins (ANTPs or NAPs) to form complexes of various sizes which are resistant to acidic pH and protease degradation. BoNT trafficking from the digestive tract to the target neurons is still a matter of debate. BoNTs use different strategies to pass through the intestinal barrier including passage of BoNT complexes containing hemagglutinins (HAs) via M cells, HA-dependent perturbation of E-cadherin intercellular junctions between enterocytes and paracellular passage of BoNT complexes, and transcytosis of BoNT free of NAPs through certain intestinal epithelial cells. Then, BoNTs target neuronal cells, preferentially cholinergic neurons, in the intestinal mucosa and submucosa. The precise mode of BoNT dissemination until the final target neuro-muscular junctions is still elusive.
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Affiliation(s)
- Yukako Fujinaga
- Department of Bacteriology, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
| | - Michel R Popoff
- Bactéries Anaérobies et Toxines, Institut Pasteur, Paris, France.
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30
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Yao G, Lam KH, Weisemann J, Peng L, Krez N, Perry K, Shoemaker CB, Dong M, Rummel A, Jin R. A camelid single-domain antibody neutralizes botulinum neurotoxin A by blocking host receptor binding. Sci Rep 2017; 7:7438. [PMID: 28785006 PMCID: PMC5547058 DOI: 10.1038/s41598-017-07457-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 06/23/2017] [Indexed: 01/07/2023] Open
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 (HCA1) at 1.68 Å resolution. The structure revealed that ciA-C2 partially occupies the SV2-binding site on HCA1, causing direct interference of HCA1 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.
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Affiliation(s)
- Guorui Yao
- Department of Physiology and Biophysics, University of California, Irvine, California, USA
| | - Kwok-Ho Lam
- Department of Physiology and Biophysics, University of California, Irvine, California, USA
| | - Jasmin Weisemann
- Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Lisheng Peng
- Department of Urology, Boston Children's Hospital, Department of Microbiology and Immunobiology and Department of Surgery, Harvard Medical School, Boston, Massachusetts, USA
| | - Nadja Krez
- Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Kay Perry
- NE-CAT and Department of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Argonne, Illinois, USA
| | - Charles B Shoemaker
- Department of Infectious Diseases and Global Health, Tufts Clinical and Translational Science Institute, North Grafton, Massachusetts, USA
| | - Min Dong
- Department of Urology, Boston Children's Hospital, Department of Microbiology and Immunobiology and Department of Surgery, Harvard Medical School, Boston, Massachusetts, USA
| | - Andreas Rummel
- Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Rongsheng Jin
- Department of Physiology and Biophysics, University of California, Irvine, California, USA.
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31
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Identification and characterization of a novel botulinum neurotoxin. Nat Commun 2017; 8:14130. [PMID: 28770820 PMCID: PMC5543303 DOI: 10.1038/ncomms14130] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 12/02/2016] [Indexed: 12/19/2022] Open
Abstract
Botulinum neurotoxins are known to have seven serotypes (BoNT/A-G). Here we report a new BoNT serotype, tentatively named BoNT/X, which has the lowest sequence identity with other BoNTs and is not recognized by antisera against known BoNTs. Similar to BoNT/B/D/F/G, BoNT/X cleaves vesicle-associated membrane proteins (VAMP) 1, 2 and 3, but at a novel site (Arg66-Ala67 in VAMP2). Remarkably, BoNT/X is the only toxin that also cleaves non-canonical substrates VAMP4, VAMP5 and Ykt6. To validate its activity, a small amount of full-length BoNT/X was assembled by linking two non-toxic fragments using a transpeptidase (sortase). Assembled BoNT/X cleaves VAMP2 and VAMP4 in cultured neurons and causes flaccid paralysis in mice. Thus, BoNT/X is a novel BoNT with a unique substrate profile. Its discovery posts a challenge to develop effective countermeasures, provides a novel tool for studying intracellular membrane trafficking, and presents a new potential therapeutic toxin for modulating secretions in cells.
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32
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Masuyer G, Conrad J, Stenmark P. The structure of the tetanus toxin reveals pH-mediated domain dynamics. EMBO Rep 2017; 18:1306-1317. [PMID: 28645943 PMCID: PMC5538627 DOI: 10.15252/embr.201744198] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 05/16/2017] [Accepted: 05/23/2017] [Indexed: 11/09/2022] Open
Abstract
The tetanus neurotoxin (TeNT) is a highly potent toxin produced by Clostridium tetani that inhibits neurotransmission of inhibitory interneurons, causing spastic paralysis in the tetanus disease. TeNT differs from the other clostridial neurotoxins by its unique ability to target the central nervous system by retrograde axonal transport. The crystal structure of the tetanus toxin reveals a "closed" domain arrangement stabilised by two disulphide bridges, and the molecular details of the toxin's interaction with its polysaccharide receptor. An integrative analysis combining X-ray crystallography, solution scattering and single particle electron cryo-microscopy reveals pH-mediated domain rearrangements that may give TeNT the ability to adapt to the multiple environments encountered during intoxication, and facilitate binding to distinct receptors.
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Affiliation(s)
- Geoffrey Masuyer
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Julian Conrad
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
- Science for Life Laboratory, Stockholm University, Solna, Sweden
| | - Pål Stenmark
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
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33
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Burns JR, Lambert GS, Baldwin MR. Insights into the Mechanisms by Which Clostridial Neurotoxins Discriminate between Gangliosides. Biochemistry 2017; 56:2571-2583. [DOI: 10.1021/acs.biochem.6b01246] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Joshua R. Burns
- Department of Molecular Microbiology
and Immunology, University of Missouri School of Medicine, Columbia, Missouri 65212, United States
| | - Gregory S. Lambert
- Department of Molecular Microbiology
and Immunology, University of Missouri School of Medicine, Columbia, Missouri 65212, United States
| | - Michael R. Baldwin
- Department of Molecular Microbiology
and Immunology, University of Missouri School of Medicine, Columbia, Missouri 65212, United States
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34
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Connan C, Popoff MR. Uptake of Clostridial Neurotoxins into Cells and Dissemination. Curr Top Microbiol Immunol 2017; 406:39-78. [PMID: 28879524 DOI: 10.1007/82_2017_50] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Clostridial neurotoxins, botulinum neurotoxins (BoNT) and tetanus neurotoxin (TeNT), are potent toxins, which are responsible for severe neurological diseases in man and animals. BoNTs induce a flaccid paralysis (botulism) by inhibiting acetylcholine release at the neuromuscular junctions, whereas TeNT causes a spastic paralysis (tetanus) by blocking the neurotransmitter release (glycine, GABA) in inhibitory interneurons within the central nervous system. Clostridial neurotoxins recognize specific receptor(s) on the target neuronal cells and enter via a receptor-mediated endocytosis. They transit through an acidic compartment which allows the translocation of the catalytic chain into the cytosol, a prerequisite step for the intracellular activity of the neurotoxins. TeNT migrates to the central nervous system by using a motor neuron as transport cell. TeNT enters a neutral pH compartment and undergoes a retrograde axonal transport to the spinal cord or brain, where the whole undissociated toxin is delivered and interacts with target neurons. Botulism most often results from ingestion of food contaminated with BoNT. Thus, BoNT passes through the intestinal epithelial barrier mainly via a transcytotic mechanism and then diffuses or is transported to the neuromuscular junctions by the lymph or blood circulation. Indeed, clostridial neurotoxins are specific neurotoxins which transit through a transport cell to gain access to the target neuron, and use distinct trafficking pathways in both cell types.
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Affiliation(s)
- Chloé Connan
- Unité Des Bactéries Anaérobies et Toxines, Institut Pasteur, 25 Rue Du Dr Roux, 75724, Paris Cedex 15, France
| | - Michel R Popoff
- Unité Des Bactéries Anaérobies et Toxines, Institut Pasteur, 25 Rue Du Dr Roux, 75724, Paris Cedex 15, France.
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35
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BoNT/AB hybrid maintains similar duration of paresis as BoNT/A wild-type in murine running wheel assay. Neurotoxicology 2016; 59:1-8. [PMID: 28043867 DOI: 10.1016/j.neuro.2016.12.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Revised: 12/15/2016] [Accepted: 12/27/2016] [Indexed: 11/21/2022]
Abstract
The highly potent Botulinum neurotoxins (BoNT) are successful drugs to treat neuromuscular disorders. Efforts are being made to further reduce the injected BoNT dose and to lengthen the interval between treatments. Detailed knowledge of the BoNT structure-activity relationship (SAR) allows combining the best features of the different BoNT serotypes. Of all seven BoNT serotypes A-G, BoNT/A displays the highest potency despite low neuronal binding affinity, while BoNT/B exhibits much higher affinity. Recently, a new BoNT/AB hybrid (AABB) was constructed comprising the catalytic and translocation domain of BoNT/A and the 50kDa cell binding domain of BoNT/B. Here, we compared BoNT/A wild-type (AAAA) and AABB with regard to ex vivo potency and in vivo potency, efficacy and duration of action using the mouse phrenic nerve hemidiaphragm assay and the murine running wheel assay, respectively. The ex vivo potency of AABB was found to be 8.4-fold higher than that of AAAA. For the latter, two and 5 pg each of AAAA and AABB, respectively, were bilaterally injected into the calf muscles and mouse running wheel performance was automatically monitored during the following weeks to determine potency, efficacy and duration. Mice displayed a dose-dependent impairment of running performance. AABB showed potency, efficacy and duration equal to AAAA demonstrating successful exchange of the cell binding domain. AABB might combine the higher potency and longer duration of BoNT/A with the target specificity for the autonomic nervous system of BoNT/B. AABB might therefore constitute an improved treatment option for acetylcholine-mediated autonomic disorders such as hypersalivation or hyperhidrosis.
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Entry of Botulinum Neurotoxin Subtypes A1 and A2 into Neurons. Infect Immun 2016; 85:IAI.00795-16. [PMID: 27795365 DOI: 10.1128/iai.00795-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 10/05/2016] [Indexed: 11/20/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are the most toxic proteins for humans but also are common therapies for neurological diseases. BoNTs are dichain toxins, comprising an N-terminal catalytic domain (LC) disulfide bond linked to a C-terminal heavy chain (HC) which includes a translocation domain (HN) and a receptor binding domain (HC). Recently, the BoNT serotype A (BoNT/A) subtypes A1 and A2 were reported to possess similar potencies but different rates of cellular intoxication and pathology in a mouse model of botulism. The current study measured HCA1 and HCA2 entry into rat primary neurons and cultured Neuro2A cells. We found that there were two sequential steps during the association of BoNT/A with neurons. The initial step was ganglioside dependent, while the subsequent step involved association with synaptic vesicles. HCA1 and HCA2 entered the same population of synaptic vesicles and entered cells at similar rates. The primary difference was that HCA2 had a higher degree of receptor occupancy for cells and neurons than HcA1. Thus, HCA2 and HCA1 share receptors and entry pathway but differ in their affinity for receptor. The initial interaction of HCA1 and HCA2 with neurons may contribute to the unique pathologies of BoNT/A1 and BoNT/A2 in mouse models.
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Hamark C, Berntsson RPA, Masuyer G, Henriksson LM, Gustafsson R, Stenmark P, Widmalm G. Glycans Confer Specificity to the Recognition of Ganglioside Receptors by Botulinum Neurotoxin A. J Am Chem Soc 2016; 139:218-230. [PMID: 27958736 DOI: 10.1021/jacs.6b09534] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The highly poisonous botulinum neurotoxins, produced by the bacterium Clostridium botulinum, act on their hosts by a high-affinity association to two receptors on neuronal cell surfaces as the first step of invasion. The glycan motifs of gangliosides serve as initial coreceptors for these protein complexes, whereby a membrane protein receptor is bound. Herein we set out to characterize the carbohydrate minimal binding epitope of the botulinum neurotoxin serotype A. By means of ligand-based NMR spectroscopy, X-ray crystallography, computer simulations, and isothermal titration calorimetry, a screening of ganglioside analogues together with a detailed characterization of various carbohydrate ligand complexes with the toxin were accomplished. We show that the representation of the glycan epitope to the protein affects the details of binding. Notably, both branches of the oligosaccharide GD1a can associate to botulinum neurotoxin serotype A when expressed as individual trisaccharides. It is, however, the terminal branch of GD1a as well as this trisaccharide motif alone, corresponding to the sialyl-Thomsen-Friedenreich antigen, that represents the active ligand epitope, and these compounds bind to the neurotoxin with a high degree of predisposition but with low affinities. This finding does not correlate with the oligosaccharide moieties having a strong contribution to the total affinity, which was expected to be the case. We here propose that the glycan part of the ganglioside receptors mainly provides abundance and specificity, whereas the interaction with the membrane itself and protein receptor brings about the strong total binding of the toxin to the neuronal membrane.
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Affiliation(s)
- Christoffer Hamark
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University , S-106 91 Stockholm, Sweden
| | - Ronnie P-A Berntsson
- Department of Biochemistry and Biophysics, Arrhenius Laboratory, Stockholm University , S-106 91 Stockholm, Sweden
| | - Geoffrey Masuyer
- Department of Biochemistry and Biophysics, Arrhenius Laboratory, Stockholm University , S-106 91 Stockholm, Sweden
| | - Linda M Henriksson
- Department of Biochemistry and Biophysics, Arrhenius Laboratory, Stockholm University , S-106 91 Stockholm, Sweden
| | - Robert Gustafsson
- Department of Biochemistry and Biophysics, Arrhenius Laboratory, Stockholm University , S-106 91 Stockholm, Sweden
| | - Pål Stenmark
- Department of Biochemistry and Biophysics, Arrhenius Laboratory, Stockholm University , S-106 91 Stockholm, Sweden
| | - Göran Widmalm
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University , S-106 91 Stockholm, Sweden
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Yao G, Zhang S, Mahrhold S, Lam KH, Stern D, Bagramyan K, Perry K, Kalkum M, Rummel A, Dong M, Jin R. N-linked glycosylation of SV2 is required for binding and uptake of botulinum neurotoxin A. Nat Struct Mol Biol 2016; 23:656-62. [PMID: 27294781 PMCID: PMC5033645 DOI: 10.1038/nsmb.3245] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 05/13/2016] [Indexed: 02/01/2023]
Abstract
Botulinum neurotoxin serotype A1 (BoNT/A1), a licensed drug widely used for medical and cosmetic applications, exerts its action by invading motoneurons. Here we report a 2.0-Å-resolution crystal structure of the BoNT/A1 receptor-binding domain in complex with its neuronal receptor, glycosylated human SV2C. We found that the neuronal tropism of BoNT/A1 requires recognition of both the peptide moiety and an N-linked glycan on SV2. This N-glycan-which is conserved in all SV2 isoforms across vertebrates-is essential for BoNT/A1 binding to neurons and for its potent neurotoxicity. The glycan-binding interface on SV2 is targeted by a human BoNT/A1-neutralizing antibody currently licensed as an antibotulism drug. Our studies reveal a new paradigm of host-pathogen interactions, in which pathogens exploit conserved host post-translational modifications, thereby achieving highly specific receptor binding while also tolerating genetic changes across multiple isoforms of receptors.
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Affiliation(s)
- Guorui Yao
- Department of Physiology and Biophysics, University of California, Irvine, California, USA
| | - Sicai Zhang
- Department of Urology, Boston Children’s Hospital, Department of Microbiology and Immunobiology and Department of Surgery, Harvard Medical School, Boston, Massachusetts, USA
| | - Stefan Mahrhold
- Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Kwok-ho Lam
- Department of Physiology and Biophysics, University of California, Irvine, California, USA
| | - Daniel Stern
- Centre for Biological Threats and Special Pathogens - Biological Toxins (ZBS3), Robert Koch-Institut, Berlin, Germany
| | - Karine Bagramyan
- Department of Molecular Immunology, Beckman Research Institute of City of Hope, Duarte, California USA
| | - Kay Perry
- NE-CAT and Department of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Argonne, Illinois USA
| | - Markus Kalkum
- Department of Molecular Immunology, Beckman Research Institute of City of Hope, Duarte, California USA
| | - Andreas Rummel
- Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Min Dong
- Department of Urology, Boston Children’s Hospital, Department of Microbiology and Immunobiology and Department of Surgery, Harvard Medical School, Boston, Massachusetts, USA
| | - Rongsheng Jin
- Department of Physiology and Biophysics, University of California, Irvine, California, USA
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Only the complex N559-glycan in the synaptic vesicle glycoprotein 2C mediates high affinity binding to botulinum neurotoxin serotype A1. Biochem J 2016; 473:2645-54. [PMID: 27313224 DOI: 10.1042/bcj20160439] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 06/16/2016] [Indexed: 11/17/2022]
Abstract
The extraordinary potency of botulinum neurotoxins (BoNTs) is mediated by their high neurospecificity, targeting peripheral cholinergic motoneurons leading to flaccid paralysis and successive respiratory failure. Complex polysialo gangliosides accumulate BoNTs on the plasma membrane and facilitate subsequent binding to synaptic vesicle membrane proteins which results in toxin endocytosis. The luminal domain 4 (LD4) of the three synaptic vesicle glycoprotein 2 (SV2) isoforms A-C mediates uptake of the clinically most relevant serotype BoNT/A1. SV2C-LD4 exhibits the strongest protein-protein interaction and comprises five putative N-glycosylation sites (PNG sites). Here, we expressed human SV2C-LD4 fused to human IgG-Fc in prokaryotic and eukaryotic expression systems to analyse the effect of N-glycosylation of SV2C on the interaction with BoNT/A1. Mass spectrometric analysis of gSV2CLD-Fc demonstrates glycosylation of N534, N559 and N565, the latter two residing at the BoNT/A interface. Mutational analysis demonstrates that only the N559-glycan, but not N565-glycan increases affinity of BoNT/A for human gSV2C-LD4. The N559-glycan was characterised as a complex core-fucosylated type with a heterogeneity ranging up to tetra-antennary structure with bisecting N-acetylglucosamine which can establish extensive interactions with BoNT/A. The mutant gSV2CLD-Fc N559A displayed a 50-fold increased dissociation rate kd resulting in an overall 12-fold decreased binding affinity in surface plasmon resonance (SPR) experiments. The delayed dissociation might provide BoNT/A more time for endocytosis into synaptic vesicles. In conclusion, we show the importance of the complex N559-glycan of SV2C-LD4, adding a third anchor point beside a ganglioside and the SV2C-LD4 peptide, for BoNT/A neuronal cell surface binding and uptake.
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Kutschenko A, Manig A, Reinert MC, Mönnich A, Liebetanz D. In-vivo comparison of the neurotoxic potencies of incobotulinumtoxinA, onabotulinumtoxinA, and abobotulinumtoxinA. Neurosci Lett 2016; 627:216-21. [PMID: 27268041 DOI: 10.1016/j.neulet.2016.06.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 05/31/2016] [Accepted: 06/01/2016] [Indexed: 11/27/2022]
Abstract
Three botulinum neurotoxin type A (BoNT/A) products, incobotulinumtoxinA, onabotulinumtoxinA, and abobotulinumtoxinA, all manufactured by different methods, are employed in clinical practice. Comparing the three BoNT/A products is difficult because their concentrations and volumes differ and the precise dose equivalence ratio is not known. We aimed to compare the neurotoxic potencies by a systematic analysis of injected volume and dose. The potency of BoNT in inducing hind limb paresis was assessed by analyzing the wheel-running performance of mice. To standardize the volume, the effect of an identical dose of incobotulinumtoxinA dissolved in different volumes of saline (15, 10, 5, and 2μl) was studied in four groups of mice (n=13-15). The potencies of the BoNT products were then compared by injecting identical volumes (10μl) containing different doses into both hind leg muscles. Mice injected with incobotulinumtoxinA showed a volume-dependent reduction in wheel-running, with larger volumes inducing more intense paresis. A standardized volume containing the same number of mouse units of the BoNT/A products produced different degrees of paresis. The conversion ratio of incobotulinumtoxinA and onabotulinumtoxinA is estimated to be between 1:0.75 and 1:0.5. OnabotulinumtoxinA displayed a two-fold greater potency than abobotulinumtoxinA. Doses of onabotulinumtoxinA and abobotulinumtoxinA that produce an identical severity of pareses even result in the same duration of pareses. This wheel-running assay allows one to compare the neurotoxic potency of different volumes and doses of the BoNT products in vivo. Our results argue against common clinical practice because incobotulinumtoxinA and onabotulinumtoxinA are not readily interchangeable and a two-fold dose of abobotulinumtoxinA is needed to induce an effect identical to onabotulinumtoxinA. In addition, this emphasizes that the duration of BoNT-induced effect is the same as long as equipotent doses of BoNT are injected.
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Affiliation(s)
- Anna Kutschenko
- Department of Clinical Neurophysiology, University Medical Centre Göttingen, Göttingen, Germany.
| | - Anja Manig
- Department of Clinical Neurophysiology, University Medical Centre Göttingen, Göttingen, Germany
| | - Marie-Christine Reinert
- Department of Clinical Neurophysiology, University Medical Centre Göttingen, Göttingen, Germany
| | - Angelika Mönnich
- Department of Clinical Neurophysiology, University Medical Centre Göttingen, Göttingen, Germany
| | - David Liebetanz
- Department of Clinical Neurophysiology, University Medical Centre Göttingen, Göttingen, Germany
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Botulinum Neurotoxin Serotype A Recognizes Its Protein Receptor SV2 by a Different Mechanism than Botulinum Neurotoxin B Synaptotagmin. Toxins (Basel) 2016; 8:toxins8050154. [PMID: 27196927 PMCID: PMC4885069 DOI: 10.3390/toxins8050154] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 04/28/2016] [Accepted: 05/09/2016] [Indexed: 11/23/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) exhibit extraordinary potency due to their exquisite neurospecificity, which is achieved by dual binding to complex polysialo-gangliosides and synaptic vesicle proteins. The luminal domain 4 (LD4) of the three synaptic vesicle glycoprotein 2 isoforms, SV2A‐C, identified as protein receptors for the most relevant serotype BoNT/A, binds within the 50 kDa cell binding domain HC of BoNT/A. Here, we deciphered the BoNT/A‐SV2 interactions in more detail. In pull down assays, the binding of HCA to SV2-LD4 isoforms decreases from SV2C >> SV2A > SV2B. A binding constant of 200 nM was determined for BoNT/A to rat SV2C-LD4 in GST pull down assay. A similar binding constant was determined by surface plasmon resonance for HCA to rat SV2C and to human SV2C, the latter being slightly lower due to the substitution L563F in LD4. At pH 5, as measured in acidic synaptic vesicles, the binding constant of HCA to hSV2C is increased more than 10-fold. Circular dichroism spectroscopy reveals that the quadrilateral helix of SV2C-LD4 already exists in solution prior to BoNT/A binding. Hence, the BoNT/A‐SV2C interaction is of different nature compared to BoNT/B‐Syt-II. In particular, the preexistence of the quadrilateral β-sheet helix of SV2 and its pH-dependent binding to BoNT/A via backbone–backbone interactions constitute major differences. Knowledge of the molecular details of BoNT/A‐SV2 interactions drives the development of high affinity peptides to counteract BoNT/A intoxications or to capture functional BoNT/A variants in innovative detection systems for botulism diagnostic.
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Structural and Functional Interactions between Transient Receptor Potential Vanilloid Subfamily 1 and Botulinum Neurotoxin Serotype A. PLoS One 2016; 11:e0143024. [PMID: 26745805 PMCID: PMC4706438 DOI: 10.1371/journal.pone.0143024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 10/29/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Botulinum neurotoxins are produced by Clostridium botulinum bacteria. There are eight serologically distinct botulinum neurotoxin isoforms (serotypes A-H). Currently, botulinum neurotoxin serotype A (BoNT⁄A) is commonly used for the treatment of many disorders, such as hyperactive musculoskeletal disorders, dystonia, and pain. However, the effectiveness of BoNT⁄A for pain alleviation and the mechanisms that mediate the analgesic effects of BoNT⁄A remain unclear. To define the antinociceptive mechanisms by which BoNT/A functions, the interactions between BoNT⁄A and the transient receptor potential vanilloid subfamily 1 (TRPV1) were investigated using immunofluorescence, co-immunoprecipitation, and western blot analysis in primary mouse embryonic dorsal root ganglion neuronal cultures. RESULTS 1) Three-week-old cultured dorsal root ganglion neurons highly expressed transient TRPV1, synaptic vesicle 2A (SV2A) and synaptosomal-associated protein 25 (SNAP-25). SV2A and SNAP-25 are the binding receptor and target protein, respectively, of BoNT⁄A. 2) TRPV1 colocalized with both BoNT⁄A and cleaved SNAP-25 when BoNT⁄A was added to dorsal root ganglia neuronal cultures. 3) After 24 hours of BoNT⁄A treatment (1 nmol⁄l), both TRPV1 and BoNT⁄A positive bands were detected in western blots of immunoprecipitated pellets. 4) Blocking TRPV1 with a specific antibody decreased the cleavage of SNAP-25 by BoNT⁄A. CONCLUSION BoNT/A interacts with TRPV1 both structurally and functionally in cultured mouse embryonic dorsal root ganglion neurons. These results suggest that an alternative mechanism is used by BoNT⁄A to mediate pain relief.
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43
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Rummel A. Two Feet on the Membrane: Uptake of Clostridial Neurotoxins. Curr Top Microbiol Immunol 2016; 406:1-37. [PMID: 27921176 DOI: 10.1007/82_2016_48] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
The extraordinary potency of botulinum neurotoxins (BoNT) and tetanus neurotoxin (TeNT) is mediated by their high neurospecificity, targeting peripheral cholinergic motoneurons leading to flaccid and spastic paralysis, respectively, and successive respiratory failure. Complex polysialo gangliosides accumulate BoNT and TeNT on the plasma membrane. The ganglioside binding in BoNT/A, B, E, F, G, and TeNT occurs via a conserved ganglioside-binding pocket within the most carboxyl-terminal 25 kDa domain HCC, whereas BoNT/C, DC, and D display here two different ganglioside binding sites. This enrichment step facilitates subsequent binding of BoNT/A, B, DC, D, E, F, and G to the intraluminal domains of the synaptic vesicle glycoprotein 2 (SV2) isoforms A-C and synaptotagmin-I/-II, respectively. Whereas an induced α-helical 20-mer Syt peptide binds via side chain interactions to the tip of the HCC domain of BoNT/B, DC and G, the preexisting, quadrilateral β-sheet helix of SV2C-LD4 binds the clinically most relevant serotype BoNT/A mainly through backbone-backbone interactions at the interface of HCC and HCN. In addition, the conserved, complex N559-glycan branch of SV2C establishes extensive interactions with BoNT/A resulting in delayed dissociation providing BoNT/A more time for endocytosis into synaptic vesicles. An analogous interaction occurs between SV2A/B and BoNT/E. Altogether, the nature of BoNT-SV2 recognition clearly differs from BoNT-Syt. Subsequently, the synaptic vesicle is recycled and the bound neurotoxin is endocytosed. Acidification of the vesicle lumen triggers membrane insertion of the translocation domain, pore formation, and finally translocation of the enzymatically active light chain into the neuronal cytosol to halt release of neurotransmitters.
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Affiliation(s)
- Andreas Rummel
- Institut Für Toxikologie, Medizinische Hochschule Hannover, 30623, Hannover, Germany.
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44
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Snake and Spider Toxins Induce a Rapid Recovery of Function of Botulinum Neurotoxin Paralysed Neuromuscular Junction. Toxins (Basel) 2015; 7:5322-36. [PMID: 26670253 PMCID: PMC4690137 DOI: 10.3390/toxins7124887] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 11/20/2015] [Accepted: 11/30/2015] [Indexed: 12/29/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) and some animal neurotoxins (β-Bungarotoxin, β-Btx, from elapid snakes and α-Latrotoxin, α-Ltx, from black widow spiders) are pre-synaptic neurotoxins that paralyse motor axon terminals with similar clinical outcomes in patients. However, their mechanism of action is different, leading to a largely-different duration of neuromuscular junction (NMJ) blockade. BoNTs induce a long-lasting paralysis without nerve terminal degeneration acting via proteolytic cleavage of SNARE proteins, whereas animal neurotoxins cause an acute and complete degeneration of motor axon terminals, followed by a rapid recovery. In this study, the injection of animal neurotoxins in mice muscles previously paralyzed by BoNT/A or /B accelerates the recovery of neurotransmission, as assessed by electrophysiology and morphological analysis. This result provides a proof of principle that, by causing the complete degeneration, reabsorption, and regeneration of a paralysed nerve terminal, one could favour the recovery of function of a biochemically- or genetically-altered motor axon terminal. These observations might be relevant to dying-back neuropathies, where pathological changes first occur at the neuromuscular junction and then progress proximally toward the cell body.
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45
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Weisemann J, Krez N, Fiebig U, Worbs S, Skiba M, Endermann T, Dorner MB, Bergström T, Muñoz A, Zegers I, Müller C, Jenkinson SP, Avondet MA, Delbrassinne L, Denayer S, Zeleny R, Schimmel H, Åstot C, Dorner BG, Rummel A. Generation and Characterization of Six Recombinant Botulinum Neurotoxins as Reference Material to Serve in an International Proficiency Test. Toxins (Basel) 2015; 7:5035-54. [PMID: 26703728 PMCID: PMC4690111 DOI: 10.3390/toxins7124861] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 11/10/2015] [Accepted: 11/13/2015] [Indexed: 12/22/2022] Open
Abstract
The detection and identification of botulinum neurotoxins (BoNT) is complex due to the existence of seven serotypes, derived mosaic toxins and more than 40 subtypes. Expert laboratories currently use different technical approaches to detect, identify and quantify BoNT, but due to the lack of (certified) reference materials, analytical results can hardly be compared. In this study, the six BoNT/A1–F1 prototypes were successfully produced by recombinant techniques, facilitating handling, as well as improving purity, yield, reproducibility and biosafety. All six BoNTs were quantitatively nicked into active di-chain toxins linked by a disulfide bridge. The materials were thoroughly characterized with respect to purity, identity, protein concentration, catalytic and biological activities. For BoNT/A1, B1 and E1, serotypes pathogenic to humans, the catalytic activity and the precise protein concentration were determined by Endopep-mass spectrometry and validated amino acid analysis, respectively. In addition, BoNT/A1, B1, E1 and F1 were successfully detected by immunological assays, unambiguously identified by mass spectrometric-based methods, and their specific activities were assigned by the mouse LD50 bioassay. The potencies of all six BoNT/A1–F1 were quantified by the ex vivo mouse phrenic nerve hemidiaphragm assay, allowing a direct comparison. In conclusion, highly pure recombinant BoNT reference materials were produced, thoroughly characterized and employed as spiking material in a worldwide BoNT proficiency test organized by the EQuATox consortium.
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Affiliation(s)
| | - Nadja Krez
- Toxogen GmbH, Feodor-Lynen-Str. 35, 30625 Hannover, Germany.
| | - Uwe Fiebig
- Biological Toxins, Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestr. 10, 13353 Berlin, Germany.
| | - Sylvia Worbs
- Biological Toxins, Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestr. 10, 13353 Berlin, Germany.
| | - Martin Skiba
- Biological Toxins, Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestr. 10, 13353 Berlin, Germany.
| | - Tanja Endermann
- Biological Toxins, Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestr. 10, 13353 Berlin, Germany.
| | - Martin B Dorner
- Biological Toxins, Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestr. 10, 13353 Berlin, Germany.
| | - Tomas Bergström
- Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Cementvägen 20, 90182 Umeå, Sweden.
| | - Amalia Muñoz
- Joint Research Centre, Institute for Reference Materials and Measurements, European Commission, Retieseweg 111, 2440 Geel, Belgium.
| | - Ingrid Zegers
- Joint Research Centre, Institute for Reference Materials and Measurements, European Commission, Retieseweg 111, 2440 Geel, Belgium.
| | - Christian Müller
- Federal Department of Defence, Civil Protection and Sport-Spiez Laboratory, Austrasse 1, 3700 Spiez, Switzerland.
| | - Stephen P Jenkinson
- Federal Department of Defence, Civil Protection and Sport-Spiez Laboratory, Austrasse 1, 3700 Spiez, Switzerland.
| | - Marc-Andre Avondet
- Federal Department of Defence, Civil Protection and Sport-Spiez Laboratory, Austrasse 1, 3700 Spiez, Switzerland.
| | - Laurence Delbrassinne
- Scientific Service of Food-Borne Pathogens, Operational Directorate of Communicable and Infectious Diseases, Scientific Institute of Public Health (WIV-ISP), 1050 Brussels, Belgium.
| | - Sarah Denayer
- Scientific Service of Food-Borne Pathogens, Operational Directorate of Communicable and Infectious Diseases, Scientific Institute of Public Health (WIV-ISP), 1050 Brussels, Belgium.
| | - Reinhard Zeleny
- Joint Research Centre, Institute for Reference Materials and Measurements, European Commission, Retieseweg 111, 2440 Geel, Belgium.
| | - Heinz Schimmel
- Joint Research Centre, Institute for Reference Materials and Measurements, European Commission, Retieseweg 111, 2440 Geel, Belgium.
| | - Crister Åstot
- Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Cementvägen 20, 90182 Umeå, Sweden.
| | - Brigitte G Dorner
- Biological Toxins, Centre for Biological Threats and Special Pathogens, Robert Koch Institute, Seestr. 10, 13353 Berlin, Germany.
| | - Andreas Rummel
- Toxogen GmbH, Feodor-Lynen-Str. 35, 30625 Hannover, Germany.
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46
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Botulinum Neurotoxins: Qualitative and Quantitative Analysis Using the Mouse Phrenic Nerve Hemidiaphragm Assay (MPN). Toxins (Basel) 2015; 7:4895-905. [PMID: 26610569 PMCID: PMC4690105 DOI: 10.3390/toxins7124855] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 08/26/2015] [Accepted: 09/01/2015] [Indexed: 12/30/2022] Open
Abstract
The historical method for the detection of botulinum neurotoxin (BoNT) is represented by the mouse bioassay (MBA) measuring the animal survival rate. Since the endpoint of the MBA is the death of the mice due to paralysis of the respiratory muscle, an ex vivo animal replacement method, called mouse phrenic nerve (MPN) assay, employs the isolated N. phrenicus-hemidiaphragm tissue. Here, BoNT causes a dose-dependent characteristic decrease of the contraction amplitude of the indirectly stimulated muscle. Within the EQuATox BoNT proficiency 13 test samples were analysed using the MPN assay by serial dilution to a bath concentration resulting in a paralysis time within the range of calibration curves generated with BoNT/A, B and E standards, respectively. For serotype identification the diluted samples were pre-incubated with polyclonal anti-BoNT/A, B or E antitoxin or a combination of each. All 13 samples were qualitatively correctly identified thereby delivering superior results compared to single in vitro methods like LFA, ELISA and LC-MS/MS. Having characterized the BoNT serotype, the final bath concentrations were calculated using the calibration curves and then multiplied by the respective dilution factor to obtain the sample concentration. Depending on the source of the BoNT standards used, the quantitation of ten BoNT/A containing samples delivered a mean z-score of 7 and of three BoNT/B or BoNT/E containing samples z-scores <2, respectively.
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Zanetti G, Azarnia Tehran D, Pirazzini M, Binz T, Shone CC, Fillo S, Lista F, Rossetto O, Montecucco C. Inhibition of botulinum neurotoxins interchain disulfide bond reduction prevents the peripheral neuroparalysis of botulism. Biochem Pharmacol 2015; 98:522-30. [PMID: 26449594 DOI: 10.1016/j.bcp.2015.09.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 09/29/2015] [Indexed: 12/18/2022]
Abstract
Botulinum neurotoxins (BoNTs) form a growing family of metalloproteases with a unique specificity either for VAMP, SNAP25 or syntaxin. The BoNTs are grouped in seven different serotypes indicated by letters from A to G. These neurotoxins enter the cytosol of nerve terminals via a 100 kDa chain which binds to the presynaptic membrane and assists the translocation of a 50 kDa metalloprotease chain. These two chains are linked by a single disulfide bridge which plays an essential role during the entry of the metalloprotease chain in the cytosol, but thereafter it has to be reduced to free the proteolytic activity. Its reduction is mediated by thioredoxin which is continuously regenerated by its reductase. Here we show that inhibitors of thioredoxin reductase or of thioredoxin prevent the specific proteolysis of VAMP by the four VAMP-specific BoNTs: type B, D, F and G. These compounds are effective not only in primary cultures of neurons, but also in preventing the in vivo mouse limb neuroparalysis. In addition, one of these inhibitors, Ebselen, largely protects mice from the death caused by a systemic injection. Together with recent results obtained with BoNTs specific for SNAP25 and syntaxin, the present data demonstrate the essential role of the thioredoxin-thioredoxin reductase system in reducing the interchain disulfide during the nerve intoxication mechanism of all serotypes. Therefore its inhibitors should be considered for a possible use to prevent botulism and for treating infant botulism.
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Affiliation(s)
- Giulia Zanetti
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Domenico Azarnia Tehran
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Marcon Pirazzini
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Thomas Binz
- Institut für Biochemie, OE 4310, Medizinische Hochschule Hannover, 30623 Hannover, Germany
| | - Clifford C Shone
- Public Health England, Porton Down, Salisbury, Wiltshire SP4 OJG, UK
| | - Silvia Fillo
- Histology and Molecular Biology Section, Army Medical and Veterinary Research Center, Via Santo Stefano Rotondo 4, 00184 Rome, Italy
| | - Florigio Lista
- Histology and Molecular Biology Section, Army Medical and Veterinary Research Center, Via Santo Stefano Rotondo 4, 00184 Rome, Italy
| | - Ornella Rossetto
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy
| | - Cesare Montecucco
- Dipartimento di Scienze Biomediche, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy; Istituto CNR di Neuroscienze, Università di Padova, Via U. Bassi 58/B, 35121 Padova, Italy.
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Rummel A. The long journey of botulinum neurotoxins into the synapse. Toxicon 2015; 107:9-24. [PMID: 26363288 DOI: 10.1016/j.toxicon.2015.09.009] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 08/27/2015] [Accepted: 09/08/2015] [Indexed: 01/09/2023]
Abstract
Botulinum neurotoxins (BoNT) cause the disease botulism, a flaccid paralysis of the muscle. They are also very effective, widely used medicines applied locally in sub-nanogram quantities. BoNTs are released together with several non-toxic, associated proteins as progenitor toxin complexes (PCT) by Clostridium botulinum to become highly potent oral poisons ingested via contaminated food. They block the neurotransmission in susceptible animals and humans already in nanogram quantities due to their specific ability to enter motoneurons and to cleave only selected neuronal proteins involved in neuroexocytosis. BoNTs have developed a sophisticated strategy to passage the gastrointestinal tract and to be absorbed in the intestine of the host to finally attack neurons. A non-toxic non-hemagglutinin (NTNHA) forms a binary complex with BoNT to protect it from gastrointestinal degradation. This binary M-PTC is one component of the bi-modular 14-subunit ∼760 kDa large progenitor toxin complex. The other component is the structurally and functionally independent dodecameric hemagglutinin (HA) complex which facilitates the absorption on the intestinal epithelium by glycan binding. Subsequent to its transcytosis the HA complex disrupts the tight junction of the intestinal barrier from the basolateral side by binding to E-cadherin. Now, the L-PTC can also enter the circulation by paracellular routes in much larger quantities. From here, the dissociated BoNTs reach the neuromuscular junction and accumulate via interaction with polysialo gangliosides, complex glycolipids, on motoneurons at the neuromuscular junction. Subsequently, additional specific binding to luminal segments of synaptic vesicles proteins like SV2 and synaptotagmin leads to their uptake. Finally, the neurotoxins shut down the synaptic vesicle cycle, which they had exploited before to enter their target cells, via specific cleavage of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins, which constitute the core components of the cellular membrane fusion machinery.
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Affiliation(s)
- Andreas Rummel
- Institut für Toxikologie, Medizinische Hochschule Hannover, 30623 Hannover, Germany.
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Fan Y, Dong J, Lou J, Wen W, Conrad F, Geren IN, Garcia-Rodriguez C, Smith TJ, Smith LA, Ho M, Pires-Alves M, Wilson BA, Marks JD. Monoclonal Antibodies that Inhibit the Proteolytic Activity of Botulinum Neurotoxin Serotype/B. Toxins (Basel) 2015; 7:3405-23. [PMID: 26343720 PMCID: PMC4591640 DOI: 10.3390/toxins7093405] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 08/10/2015] [Accepted: 08/18/2015] [Indexed: 12/19/2022] Open
Abstract
Existing antibodies (Abs) used to treat botulism cannot enter the cytosol of neurons and bind to botulinum neurotoxin (BoNT) at its site of action, and thus cannot reverse paralysis. However, Abs targeting the proteolytic domain of the toxin could inhibit the proteolytic activity of the toxin intracellularly and potentially reverse intoxication, if they could be delivered intracellularly. As such, antibodies that neutralize toxin activity could serve as potent inhibitory cargos for therapeutic antitoxins against botulism. BoNT serotype B (BoNT/B) contains a zinc endopeptidase light chain (LC) domain that cleaves synaoptobrevin-2, a SNARE protein responsible for vesicle fusion and acetylcholine vesicle release. To generate monoclonal Abs (mAbs) that could reverse paralysis, we targeted the protease domain for Ab generation. Single-chain variable fragment (scFv) libraries from immunized mice or humans were displayed on yeast, and 19 unique BoNT/B LC-specific mAbs isolated by fluorescence-activated cell sorting (FACS). The equilibrium dissociation constants (KD) of these mAbs for BoNT/B LC ranged from 0.24 nM to 14.3 nM (mean KD 3.27 nM). Eleven mAbs inhibited BoNT/B LC proteolytic activity. The fine epitopes of selected mAbs were identified by alanine-scanning mutagenesis, revealing that inhibitory mAbs bound near the active site, substrate-binding site or the extended substrate-binding site. The results provide mAbs that could prove useful for intracellular reversal of paralysis and identify epitopes that could be targeted by small molecules inhibitors.
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Affiliation(s)
- Yongfeng Fan
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
| | - Jianbo Dong
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
| | - Jianlong Lou
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
| | - Weihua Wen
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
| | - Fraser Conrad
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
| | - Isin N Geren
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
| | - Consuelo Garcia-Rodriguez
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
| | - Theresa J Smith
- Molecular and Translational Sciences Division, United States Army Medical Institute of Infectious Diseases, Fort Detrick, MD 21702, USA.
| | - Leonard A Smith
- Medical Countermeasures Technology, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702-5011, USA.
| | - Mengfei Ho
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Melissa Pires-Alves
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Brenda A Wilson
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - James D Marks
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
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Inhibiting oral intoxication of botulinum neurotoxin A complex by carbohydrate receptor mimics. Toxicon 2015; 107:43-9. [PMID: 26272706 DOI: 10.1016/j.toxicon.2015.08.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 08/04/2015] [Indexed: 12/21/2022]
Abstract
Botulinum neurotoxins (BoNTs) cause the disease botulism manifested by flaccid paralysis that could be fatal to humans and animals. Oral ingestion of the toxin with contaminated food is one of the most common routes for botulism. BoNT assembles with several auxiliary proteins to survive in the gastrointestinal tract and is subsequently transported through the intestinal epithelium into the general circulation. Several hemagglutinin proteins form a multi-protein complex (HA complex) that recognizes host glycans on the intestinal epithelial cell surface to facilitate BoNT absorption. Blocking carbohydrate binding to the HA complex could significantly inhibit the oral toxicity of BoNT. Here, we identify lactulose, a galactose-containing non-digestible sugar commonly used to treat constipation, as a prototype inhibitor against oral BoNT/A intoxication. As revealed by a crystal structure, lactulose binds to the HA complex at the same site where the host galactose-containing carbohydrate receptors bind. In vitro assays using intestinal Caco-2 cells demonstrated that lactulose inhibits HA from compromising the integrity of the epithelial cell monolayers and blocks the internalization of HA. Furthermore, co-administration of lactulose significantly protected mice against BoNT/A oral intoxication in vivo. Taken together, these data encourage the development of carbohydrate receptor mimics as a therapeutic intervention to prevent BoNT oral intoxication.
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