1
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Yamagata A, Ito K, Suzuki T, Dohmae N, Terada T, Shirouzu M. Structural basis for antiepileptic drugs and botulinum neurotoxin recognition of SV2A. Nat Commun 2024; 15:3027. [PMID: 38637505 PMCID: PMC11026379 DOI: 10.1038/s41467-024-47322-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 03/26/2024] [Indexed: 04/20/2024] Open
Abstract
More than one percent of people have epilepsy worldwide. Levetiracetam (LEV) is a successful new-generation antiepileptic drug (AED), and its derivative, brivaracetam (BRV), shows improved efficacy. Synaptic vesicle glycoprotein 2a (SV2A), a putative membrane transporter in the synaptic vesicles (SVs), has been identified as a target of LEV and BRV. SV2A also serves as a receptor for botulinum neurotoxin (BoNT), which is the most toxic protein and has paradoxically emerged as a potent reagent for therapeutic and cosmetic applications. Nevertheless, no structural analysis on AEDs and BoNT recognition by full-length SV2A has been available. Here we describe the cryo-electron microscopy structures of the full-length SV2A in complex with the BoNT receptor-binding domain, BoNT/A2 HC, and either LEV or BRV. The large fourth luminal domain of SV2A binds to BoNT/A2 HC through protein-protein and protein-glycan interactions. LEV and BRV occupy the putative substrate-binding site in an outward-open conformation. A propyl group in BRV creates additional contacts with SV2A, explaining its higher binding affinity than that of LEV, which was further supported by label-free spectral shift assay. Numerous LEV derivatives have been developed as AEDs and positron emission tomography (PET) tracers for neuroimaging. Our work provides a structural framework for AEDs and BoNT recognition of SV2A and a blueprint for the rational design of additional AEDs and PET tracers.
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Affiliation(s)
- Atsushi Yamagata
- Laboratory for Protein Functional and Structural Biology, RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, Japan.
| | - Kaori Ito
- Laboratory for Protein Functional and Structural Biology, RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, Japan
| | - Takehiro Suzuki
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama, Japan
| | - Naoshi Dohmae
- Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama, Japan
| | - Tohru Terada
- Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Mikako Shirouzu
- Laboratory for Protein Functional and Structural Biology, RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, Japan
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2
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Wang S, Wang D, Shen WT, Kai M, Yu Y, Peng Y, Xian N, Fang RH, Gao W, Zhang L. Protein-Loaded Cellular Nanosponges for Dual-Biomimicry Neurotoxin Countermeasure. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2309635. [PMID: 37990378 DOI: 10.1002/smll.202309635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Indexed: 11/23/2023]
Abstract
Neurotoxins present a substantial threat to human health and security as they disrupt and damage the nervous system. Their potent and structurally diverse nature poses challenges in developing effective countermeasures. In this study, a unique nanoparticle design that combines dual-biomimicry mechanisms to enhance the detoxification efficacy of neurotoxins is introduced. Using saxitoxin (STX), one of the deadliest neurotoxins, and its natural binding protein saxiphilin (Sxph) as a model system, human neuronal membrane-coated and Sxph-loaded metal-organic framework (MOF) nanosponges (denoted "Neuron-MOF/Sxph-NS") are successfully developed. The resulting Neuron-MOF/Sxph-NS exhibit a biomimetic design that not only emulates host neurons for function-based detoxification through the neuronal membrane coating, but also mimics toxin-resistant organisms by encapsulating the Sxph protein within the nanoparticle core. The comprehensive in vitro assays, including cell osmotic swelling, calcium flux, and cytotoxicity assays, demonstrate the improved detoxification efficacy of Neuron-MOF/Sxph-NS. Furthermore, in mouse models of STX intoxication, the application of Neuron-MOF/Sxph-NS shows significant survival benefits in both therapeutic and prophylactic regimens, without any apparent acute toxicity. Overall, the development of Neuron-MOF/Sxph-NS represents an important advancement in neurotoxin detoxification, offering promising potential for treating injuries and diseases caused by neurotoxins and addressing the current limitations in neurotoxin countermeasures.
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Affiliation(s)
- Shuyan Wang
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, CA, 92093, USA
| | - Dan Wang
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, CA, 92093, USA
| | - Wei-Ting Shen
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, CA, 92093, USA
| | - Mingxuan Kai
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, CA, 92093, USA
| | - Yiyan Yu
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, CA, 92093, USA
| | - Yifei Peng
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, CA, 92093, USA
| | - Nianfei Xian
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, CA, 92093, USA
| | - Ronnie H Fang
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, CA, 92093, USA
| | - Weiwei Gao
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, CA, 92093, USA
| | - Liangfang Zhang
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, CA, 92093, USA
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Harris RA, Flint A, Blondin Brosseau M, Weedmark K, Austin JW. Complete genomes of Clostridium botulinum type B(F) isolates associated with a 1995 foodborne botulism outbreak from commercial pâté reveals a recombination event disrupting the ntnh gene. Microb Genom 2024; 10:001169. [PMID: 38175697 PMCID: PMC10868621 DOI: 10.1099/mgen.0.001169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 12/08/2023] [Indexed: 01/05/2024] Open
Abstract
Foodborne botulism is a neuroparalytic disease caused by ingestion of foods contaminated with botulinum neurotoxin (BoNT), produced by Clostridium botulinum. In 1995 a husband and wife from Québec, Canada, were hospitalized for several months with prolonged muscle paralysis after ingesting a commercial pâté de campagne. Examination of faecal samples from both patients and the pâté produced viable Group I (proteolytic) C. botulinum type B from each of the three samples. Whole genome sequencing revealed that all three isolates contain identical bont/B5 and bont/F2 genes encoded on a plasmid. Both faecal isolate genomes were identical in chromosome and plasmid length, as well as gene content. The genome of the pâté isolate was nearly identical to that of the faecal isolates with the notable difference of a missing 13-gene insertion on the bont/B5 cluster disrupting the ntnh gene. Examination of the insertion revealed several mobile genetic elements that participate in recombination.
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Affiliation(s)
| | - Annika Flint
- Bureau of Microbial Hazards, Health Canada, Ottawa, Ontario, Canada
| | | | - Kelly Weedmark
- Bureau of Microbial Hazards, Health Canada, Ottawa, Ontario, Canada
| | - John W. Austin
- Bureau of Microbial Hazards, Health Canada, Ottawa, Ontario, Canada
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4
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Leka O, Wu Y, Zanetti G, Furler S, Reinberg T, Marinho J, Schaefer JV, Plückthun A, Li X, Pirazzini M, Kammerer RA. A DARPin promotes faster onset of botulinum neurotoxin A1 action. Nat Commun 2023; 14:8317. [PMID: 38110403 PMCID: PMC10728214 DOI: 10.1038/s41467-023-44102-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 11/30/2023] [Indexed: 12/20/2023] Open
Abstract
In this study, we characterize Designed Ankyrin Repeat Proteins (DARPins) as investigative tools to probe botulinum neurotoxin A1 (BoNT/A1) structure and function. We identify DARPin-F5 that completely blocks SNAP25 substrate cleavage by BoNT/A1 in vitro. X-ray crystallography reveals that DARPin-F5 inhibits BoNT/A1 activity by interacting with a substrate-binding region between the α- and β-exosite. This DARPin does not block substrate cleavage of BoNT/A3, indicating that DARPin-F5 is a subtype-specific inhibitor. BoNT/A1 Glu-171 plays a critical role in the interaction with DARPin-F5 and its mutation to Asp, the residue found in BoNT/A3, results in a loss of inhibition of substrate cleavage. In contrast to the in vitro results, DARPin-F5 promotes faster substrate cleavage of BoNT/A1 in primary neurons and muscle tissue by increasing toxin translocation. Our findings could have important implications for the application of BoNT/A1 in therapeutic areas requiring faster onset of toxin action combined with long persistence.
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Affiliation(s)
- Oneda Leka
- Laboratory of Biomolecular Research, Division of Biology, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - Yufan Wu
- Laboratory of Biomolecular Research, Division of Biology, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - Giulia Zanetti
- Department of Biomedical Sciences, University of Padova, 35121, Padova, Italy
| | - Sven Furler
- Department of Biochemistry, University of Zurich, 8057, Zurich, Switzerland
| | - Thomas Reinberg
- Department of Biochemistry, University of Zurich, 8057, Zurich, Switzerland
| | - Joana Marinho
- Department of Biochemistry, University of Zurich, 8057, Zurich, Switzerland
| | - Jonas V Schaefer
- Department of Biochemistry, University of Zurich, 8057, Zurich, Switzerland
| | - Andreas Plückthun
- Department of Biochemistry, University of Zurich, 8057, Zurich, Switzerland
| | - Xiaodan Li
- Laboratory of Biomolecular Research, Division of Biology, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - Marco Pirazzini
- Department of Biomedical Sciences, University of Padova, 35121, Padova, Italy
| | - Richard A Kammerer
- Laboratory of Biomolecular Research, Division of Biology, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland.
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5
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Lu J, Jiang Y, Guo J, Chen L, Liu F, Li Z, Liu X, Du P, Yu Y, Wang R, Yang Z. A human bispecific antibody neutralizes botulinum neurotoxin serotype A. Sci Rep 2023; 13:20806. [PMID: 38012220 PMCID: PMC10681988 DOI: 10.1038/s41598-023-48008-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 11/21/2023] [Indexed: 11/29/2023] Open
Abstract
Botulinum neurotoxin (BoNT) shows high lethality and toxicity, marking it as an important biological threat. The only effective post-exposure therapy is botulinum antitoxin; however, such products have great potential for improvement. To prevent or treat BoNT, monoclonal antibodies (mAbs) are promising agents. Herein, we aimed to construct a bispecific antibody (termed LUZ-A1-A3) based on the anti-BoNT/A human monoclonal antibodies (HMAb) A1 and A3. LUZ-A1-A3 binds to the Hc and L-HN domains of BoNT/A, displaying potent neutralization activity against BoNT/A (124 × higher than that of HMAb A1 or HMAb A3 alone and 15 × higher than that of the A1 + A3 combination). LUZ-A1-A3 provided effective protection against BoNT/A in an in vivo mouse model. Mice were protected from infection with 500 × LD50 of BoNT/A by LUZ-A1-A3 from up to 7 days before intraperitoneal administration of BoNT/A. We also demonstrated the effective therapeutic capacity of LUZ-A1-A3 against BoNT/A in a mouse model. LUZ-A1-A3 (5 μg/mouse) neutralized 20 × LD50 of BoNT/A at 3 h after intraperitoneal BoNT/A administration and complete neutralized 20 × LD50 of BoNT/A at 0.5 h after intraperitoneal BoNT/A administration. Thus, LUZ-A1-A3 is a promising agent for the pre-exposure prophylaxis and post-exposure treatment of BoNT/A.
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Affiliation(s)
- Jiansheng Lu
- Laboratory of Protein Engineering, Beijing Institute of Biotechnology, Beijing, China
| | - Yujia Jiang
- Laboratory of Protein Engineering, Beijing Institute of Biotechnology, Beijing, China
| | - Jiazheng Guo
- Laboratory of Protein Engineering, Beijing Institute of Biotechnology, Beijing, China
| | - Lei Chen
- Laboratory of Protein Engineering, Beijing Institute of Biotechnology, Beijing, China
| | - Fujia Liu
- Laboratory of Protein Engineering, Beijing Institute of Biotechnology, Beijing, China
| | - Zhiying Li
- Laboratory of Protein Engineering, Beijing Institute of Biotechnology, Beijing, China
| | - Xuyang Liu
- Laboratory of Protein Engineering, Beijing Institute of Biotechnology, Beijing, China
| | - Peng Du
- Laboratory of Protein Engineering, Beijing Institute of Biotechnology, Beijing, China
| | - Yunzhou Yu
- Laboratory of Protein Engineering, Beijing Institute of Biotechnology, Beijing, China.
| | - Rong Wang
- Laboratory of Protein Engineering, Beijing Institute of Biotechnology, Beijing, China.
| | - Zhixin Yang
- Laboratory of Protein Engineering, Beijing Institute of Biotechnology, Beijing, China.
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6
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Garvey M. Foodborne Clostridioides Species: Pathogenicity, Virulence and Biocontrol Options. Microorganisms 2023; 11:2483. [PMID: 37894141 PMCID: PMC10609181 DOI: 10.3390/microorganisms11102483] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 09/22/2023] [Accepted: 10/02/2023] [Indexed: 10/29/2023] Open
Abstract
Clostridioides species possess many virulence factors and alarming levels of muti-drug resistance which make them a significant risk to public health safety and a causative agent of livestock disease. Clostridioides result in serious systemic and gastrointestinal diseases such as myonecrosis, colitis, food poisoning and gastroenteritis. As foodborne pathogens, Clostridioides species are associated with significant incidences of morbidity and mortality where the application of broad-spectrum antibiotics predisposes patients to virulent Clostridioides colonisation. As part of the One Health approach, there is an urgent need to eliminate the use of antibiotics in food production to safeguard animals, humans and the environment. Alternative options are warranted to control foodborne pathogens at all stages of food production. Antimicrobial peptides and bacteriophages have demonstrated efficacy against Clostridioides species and may offer antimicrobial biocontrol options. The bacteriocin nisin, for example, has been implemented as a biopreservative for the control of Listeria, Staphylococcus and Clostridia species in food. Bacteriophage preparations have also gained recognition for the antibacterial action against highly virulent bacterial species including foodborne pathogens. Studies are warranted to mitigate the formulation and administration limitations associated with the application of such antimicrobials as biocontrol strategies. This review outlines foodborne Clostridioides species, their virulence factors, and potential biocontrol options for application in food production.
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Affiliation(s)
- Mary Garvey
- Department of Life Science, Atlantic Technological University, Ash Lane, F91 YW50 Sligo, Ireland;
- Centre for Precision Engineering, Materials and Manufacturing Research (PEM), Atlantic Technological University, F91 YW50 Sligo, Ireland
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7
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Tepp WH, Bradshaw M, Gardner AP, Kaufman RL, Barbieri JT, Pellett S. Botulinum Neurotoxin A4 Has a 1000-Fold Reduced Potency Due to Three Single Amino Acid Alterations in the Protein Receptor Binding Domain. Int J Mol Sci 2023; 24:5690. [PMID: 36982762 PMCID: PMC10055998 DOI: 10.3390/ijms24065690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 03/10/2023] [Accepted: 03/14/2023] [Indexed: 03/19/2023] Open
Abstract
Botulinum neurotoxin subtype A4 (BoNT/A4) is ~1000-fold less potent than BoNT/A1. This study addresses the basis for low BoNT/A4 potency. Utilizing BoNT/A1-A4 and BoNT/A4-A1 Light Chain-Heavy Chain (LC-HC) chimeras, HC-A4 was responsible for low BoNT/A4 potency. Earlier studies showed BoNT/A1-receptor binding domain (Hcc) bound a β-strand peptide (556-564) and glycan-N559 within Luminal Domain 4 (LD4) of SV2C, the BoNT/A protein receptor. Relative to BoNT/A1, the Hcc of BoNT/A4 possesses two amino acid variants (D1141 and N1142) within the β-peptide binding interface and one amino acid variant (R1292) located near the SV2C glycan-N559. Introduction of BoNT/A4 β-strand peptide variant (D1141 and N1142) into BoNT/A1 reduced toxin potency 30-fold, and additional introduction of the BoNT/A4 glycan-N559 variant (D1141, N1142, and R1292) further reduced toxin potency to approach BoNT/A4. While introduction of BoNT/A1 glycan-N559 variant (G1292) into BoNT/A4 did not alter toxin potency, additional introduction of BoNT/A1 β-strand peptide variants (G1141, S1142, and G1292) resulted in potency approaching BoNT/A1 potency. Thus, outcomes from these functional and modeling studies indicate that in rodent models, disruption of Hcc -SV2C β-peptide and -glycan-N559 interactions mediate low BoNT/A4 potency, while in human motor neurons, disruption of Hcc-SV2C β-peptide alone mediates low BoNT/A4 potency, which link to a species-specific variation at SV2C563.
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Affiliation(s)
- William H. Tepp
- Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA
| | - Marite Bradshaw
- Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA
| | - Alexander P. Gardner
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, WI 53226, USA (J.T.B.)
| | - Rebecca L. Kaufman
- Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA
| | - Joseph T. Barbieri
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, WI 53226, USA (J.T.B.)
| | - Sabine Pellett
- Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA
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8
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Molecular Diversity of BoNT-Producing Clostridia—A Still-Emerging and Challenging Problem. DIVERSITY 2023. [DOI: 10.3390/d15030392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
The diversity of BoNT-producing Clostridia is still a worrying problem for specialists who explore the evolutionary and taxonomic diversity of C. botulinum. It is also a problem for epidemiologists and laboratory staff conducting investigations into foodborne botulism in humans and animals, because their genetic and phenotypic heterogeneity cause complications in choosing the proper analytical tools and in reliably interpreting results. Botulinum neurotoxins (BoNTs) are produced by several bacterial groups that meet all the criteria of distinct species. Despite this, the historical designation of C. botulinum as the one species that produces botulinum toxins is still exploited. New genetic tools such as whole-genome sequencing (WGS) indicate horizontal gene transfer and the occurrence of botulinum gene clusters that are not limited only to Clostridium spp., but also to Gram-negative aerobic species. The literature data regarding the mentioned heterogeneity of BoNT-producing Clostridia indicate the requirement to reclassify C. botulinum species and other microorganisms able to produce BoNTs or possessing botulinum-like gene clusters. The aim of this study was to present the problem of the diversity of BoNT-producing Clostridia over time and new trends toward obtaining a reliable classification of these microorganisms, based on a complex review of the literature.
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9
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Košenina S, Stenmark P. Crystal structure of the OrfX1-OrfX3 complex from the PMP1 neurotoxin gene cluster. FEBS Lett 2023; 597:515-523. [PMID: 36403098 DOI: 10.1002/1873-3468.14542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 11/10/2022] [Indexed: 11/21/2022]
Abstract
Paraclostridial mosquitocidal protein 1 (PMP1) is a member of the clostridial neurotoxin (CNT) family, which includes botulinum and tetanus neurotoxins. PMP1 has unique selectivity for anopheline mosquitos and is the only known member of the family that targets insects. PMP1 is encoded in an orfX gene cluster, which in addition to the toxin, consists of OrfX1, OrfX2, OrfX3, P47 and NTNH, which have been shown to aid in PMP1 toxicity. We here show that OrfX1 and OrfX3 form a complex and present its structure at 2.7 Å. The OrfX1-OrfX3 complex mimics the structure of full-length OrfX2 and belongs to the lipid-binding TULIP protein superfamily. With this report, the structures of all proteins encoded in the orfX gene cluster of CNTs are now determined.
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Affiliation(s)
- Sara Košenina
- Department of Biochemistry and Biophysics, Stockholm University, Sweden
| | - Pål Stenmark
- Department of Biochemistry and Biophysics, Stockholm University, Sweden
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10
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A Comprehensive Structural Analysis of Clostridium botulinum Neurotoxin A Cell-Binding Domain from Different Subtypes. Toxins (Basel) 2023; 15:toxins15020092. [PMID: 36828407 PMCID: PMC9966434 DOI: 10.3390/toxins15020092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/11/2023] [Accepted: 01/16/2023] [Indexed: 01/20/2023] Open
Abstract
Botulinum neurotoxins (BoNTs) cause flaccid neuromuscular paralysis by cleaving one of the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complex proteins. BoNTs display high affinity and specificity for neuromuscular junctions, making them one of the most potent neurotoxins known to date. There are seven serologically distinct BoNTs (serotypes BoNT/A to BoNT/G) which can be further divided into subtypes (e.g., BoNT/A1, BoNT/A2…) based on small changes in their amino acid sequence. Of these, BoNT/A1 and BoNT/B1 have been utilised to treat various diseases associated with spasticity and hypersecretion. There are potentially many more BoNT variants with differing toxicological profiles that may display other therapeutic benefits. This review is focused on the structural analysis of the cell-binding domain from BoNT/A1 to BoNT/A6 subtypes (HC/A1 to HC/A6), including features such as a ganglioside binding site (GBS), a dynamic loop, a synaptic vesicle glycoprotein 2 (SV2) binding site, a possible Lys-Cys/Cys-Cys bridge, and a hinge motion between the HCN and HCC subdomains. Characterising structural features across subtypes provides a better understanding of how the cell-binding domain functions and may aid the development of novel therapeutics.
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11
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Wang D, Ai X, Duan Y, Xian N, Fang RH, Gao W, Zhang L. Neuronal Cellular Nanosponges for Effective Detoxification of Neurotoxins. ACS NANO 2022; 16:19145-19154. [PMID: 36354967 DOI: 10.1021/acsnano.2c08319] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Neurotoxins attack and destruct the nervous system, which can cause serious health problems and security threats. Existing detoxification approaches, such as antibodies and small molecule antidotes, rely on neurotoxin's molecular structure as design cues and require toxin-specific development for each type of toxins. However, the enormous diversity of neurotoxins makes such structure-based development of antitoxin particularly challenging and inefficient. Here, we report on the development and use of neuronal membrane-coated nanosponges (denoted "Neuron-NS") as an effective approach to detoxifying neurotoxins. Specifically, Neuron-NS act as neuron decoys to lure neurotoxins, bind with and neutralize the toxins, and thus block them from attacking the host neuron cells. These nanosponges detoxify neurotoxins regardless of their molecular structures and therefore can overcome the challenge posed by toxin structural diversity. In the study, we fabricate Neuron-NS by coating the membrane of Neuro-2a cells onto polymeric cores. Meanwhile, we select tetrodotoxin (TTX) as a model neurotoxin and demonstrate the detoxification efficacy of the Neuron-NS in a cytotoxicity assay, a calcium flux assay, and a cell osmotic swelling assay in vitro. Additionally, in mouse models of TTX intoxication, the Neuron-NS significantly enhance mouse survival in therapeutic and prophylactic regimens without showing acute toxicity. Overall, the Neuron-NS contribute to the current detoxification arsenal with the potential to treat various injuries and diseases caused by neurotoxins.
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Affiliation(s)
- Dan Wang
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, California 92093, United States
| | - Xiangzhao Ai
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, California 92093, United States
| | - Yaou Duan
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, California 92093, United States
| | - Nianfei Xian
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, California 92093, United States
| | - Ronnie H Fang
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, California 92093, United States
| | - Weiwei Gao
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, California 92093, United States
| | - Liangfang Zhang
- Department of NanoEngineering and Chemical Engineering Program, University of California San Diego, La Jolla, California 92093, United States
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12
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Advances in Clostridial and Related Neurotoxins. Int J Mol Sci 2022; 23:ijms232214076. [PMID: 36430554 PMCID: PMC9697359 DOI: 10.3390/ijms232214076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 11/10/2022] [Indexed: 11/18/2022] Open
Abstract
The huge advances in genomics and molecular biology in the past two decades have made now an exciting time to study bacterial toxins, in particular, the most potent bacterial toxin known to humankind, botulinum neurotoxins (BoNTs) [...].
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13
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Bowe BK, Wentz TG, Gregg BM, Tepp WH, Schill KM, Sharma S, Pellett S. Genomic Diversity, Competition, and Toxin Production by Group I and II Clostridium botulinum Strains Used in Food Challenge Studies. Microorganisms 2022; 10:1895. [PMID: 36296172 PMCID: PMC9611418 DOI: 10.3390/microorganisms10101895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 09/16/2022] [Accepted: 09/17/2022] [Indexed: 11/16/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) produced by the bacteria Clostridium botulinum are the causative agent of human and animal botulism, a rare but serious and potentially deadly intoxication. Foodborne botulism is caused by the consumption of foods containing BoNTs, which results from contamination of foods with C. botulinum spores and toxin production by the bacteria during growth within the food. Validation of the safety of food products is essential in preventing foodborne botulism, however, limited guidance and standards exist for the selection of strains used in C. botulinum food challenge studies. Sequencing and genomics studies have revealed that C. botulinum is a large, diverse, and polyphyletic species, with physiologic and growth characteristics studied only in a few representatives. Little is known about potential growth competition or effects on toxin production between C. botulinum strains. In this study, we investigated an applied cocktail of ten C. botulinum strains, seven Group I and three Group II. Whole genome SNP alignments revealed that this strain cocktail encompasses the major clades of the Group I and II C. botulinum species. While growth competition appears to exist between several of the strains, the cocktail as a whole resulted in high levels of BoNT production.
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Affiliation(s)
- Brooke Kathryn Bowe
- Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
- Food Research Institute, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
| | - Travis Gwynn Wentz
- Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
| | - Brieana Marie Gregg
- Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
| | - William Howard Tepp
- Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
| | - Kristin Marie Schill
- Food Research Institute, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
| | - Shashi Sharma
- Division of Microbiology, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Sabine Pellett
- Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
- Food Research Institute, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
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14
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Gregory KS, Mahadeva TB, Liu SM, Acharya KR. Structural Features of Clostridium botulinum Neurotoxin Subtype A2 Cell Binding Domain. Toxins (Basel) 2022; 14:toxins14050356. [PMID: 35622602 PMCID: PMC9146395 DOI: 10.3390/toxins14050356] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 05/17/2022] [Accepted: 05/18/2022] [Indexed: 12/14/2022] Open
Abstract
Botulinum neurotoxins (BoNT) are a group of clostridial toxins that cause the potentially fatal neuroparalytic disease botulism. Although highly toxic, BoNTs are utilized as therapeutics to treat a range of neuromuscular conditions. Several serotypes (BoNT/A-/G, /X) have been identified with vastly differing toxicological profiles. Each serotype can be further sub-categorised into subtypes due to subtle variations in their protein sequence. These minor changes have been attributed to differences in both the duration of action and potency for BoNT/A subtypes. BoNTs are composed of three domains—a cell-binding domain, a translocation domain, and a catalytic domain. In this paper, we present the crystal structures of the botulinum neurotoxin A2 cell binding domain, both alone and in complex with its receptor ganglioside GD1a at 1.63 and 2.10 Å, respectively. The analysis of these structures reveals a potential redox-dependent Lys-O-Cys bridge close to the ganglioside binding site and a hinge motion between the HCN and HCC subdomains. Furthermore, we make a detailed comparison with the previously reported HC/A2:SV2C structure for a comprehensive structural analysis of HC/A2 receptor binding.
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Affiliation(s)
- Kyle S. Gregory
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK; (K.S.G.); (T.B.M.)
| | - Tejaswini B. Mahadeva
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK; (K.S.G.); (T.B.M.)
| | - Sai Man Liu
- Protein Sciences Department, Ipsen Bioinnovation Limited, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK;
| | - K. Ravi Acharya
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK; (K.S.G.); (T.B.M.)
- Correspondence: ; Tel.: +44-(0)1225-386238
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15
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Li Z, Lu J, Tan X, Wang R, Xu Q, Yu Y, Yang Z. Functional EL-HN Fragment as a Potent Candidate Vaccine for the Prevention of Botulinum Neurotoxin Serotype E. Toxins (Basel) 2022; 14:toxins14020135. [PMID: 35202162 PMCID: PMC8880310 DOI: 10.3390/toxins14020135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/08/2022] [Accepted: 02/10/2022] [Indexed: 11/21/2022] Open
Abstract
Clostridium botulinum produces botulinum neurotoxin (BoNT), which is the most toxic known protein and the causative agent of human botulism. BoNTs have similar structures and functions, comprising three functional domains: catalytic domain (L), translocation domain (HN), and receptor-binding domain (Hc). In the present study, BoNT/E was selected as a model toxin to further explore the immunological significance of each domain. The EL-HN fragment (L and HN domains of BoNT/E) retained the enzymatic activity without in vivo neurotoxicity. Extensive investigations showed EL-HN functional fragment had the highest protective efficacy and contained some functional neutralizing epitopes. Further experiments demonstrated the EL-HN provided a superior protective effect compared with the EHc or EHc and EL-HN combination. Thus, the EL-HN played an important role in immune protection against BoNT/E and could provide an excellent platform for the design of botulinum vaccines and neutralizing antibodies. The EL-HN has the potential to replace EHc or toxoid as the optimal immunogen for the botulinum vaccine.
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Affiliation(s)
- Zhen Li
- Beijing Institute of Biotechnology, Beijing 100071, China; (Z.L.); (J.L.); (X.T.); (R.W.)
- Institute of Life Science and Biotechnology, Beijing Jiaotong University, Beijing 100044, China
| | - Jiansheng Lu
- Beijing Institute of Biotechnology, Beijing 100071, China; (Z.L.); (J.L.); (X.T.); (R.W.)
| | - Xiao Tan
- Beijing Institute of Biotechnology, Beijing 100071, China; (Z.L.); (J.L.); (X.T.); (R.W.)
- Institute of Life Science and Biotechnology, Beijing Jiaotong University, Beijing 100044, China
| | - Rong Wang
- Beijing Institute of Biotechnology, Beijing 100071, China; (Z.L.); (J.L.); (X.T.); (R.W.)
| | - Qing Xu
- Institute of Life Science and Biotechnology, Beijing Jiaotong University, Beijing 100044, China
- Correspondence: (Q.X.); (Y.Y.); (Z.Y.)
| | - Yunzhou Yu
- Beijing Institute of Biotechnology, Beijing 100071, China; (Z.L.); (J.L.); (X.T.); (R.W.)
- Correspondence: (Q.X.); (Y.Y.); (Z.Y.)
| | - Zhixin Yang
- Beijing Institute of Biotechnology, Beijing 100071, China; (Z.L.); (J.L.); (X.T.); (R.W.)
- Correspondence: (Q.X.); (Y.Y.); (Z.Y.)
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16
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Wentz TG, Tremblay BJM, Bradshaw M, Doxey AC, Sharma SK, Sauer JD, Pellett S. Endogenous CRISPR-Cas Systems in Group I Clostridium botulinum and Clostridium sporogenes Do Not Directly Target the Botulinum Neurotoxin Gene Cluster. Front Microbiol 2022; 12:787726. [PMID: 35222299 PMCID: PMC8865420 DOI: 10.3389/fmicb.2021.787726] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/27/2021] [Indexed: 12/28/2022] Open
Abstract
Most strains of proteolytic group I Clostridium botulinum (G1 C. botulinum) and some strains of Clostridium sporogenes possess genes encoding botulinum neurotoxin (BoNT), a potent neuroparalytic agent. Within G1 C. botulinum, conserved bont gene clusters of three major toxin serotypes (bont/A/B/F) can be found on conjugative plasmids and/or within chromosomal pathogenicity islands. CRISPR-Cas systems enable site-specific targeting of previously encountered mobile genetic elements (MGE) such as plasmids and bacteriophage through the creation of a spacer library complementary to protospacers within the MGEs. To examine whether endogenous CRISPR-Cas systems restrict the transfer of bont gene clusters across strains we conducted a bioinformatic analysis profiling endogenous CRISPR-Cas systems from 241 G1 C. botulinum and C. sporogenes strains. Approximately 6,200 CRISPR spacers were identified across the strains and Type I-B, III-A/B/D cas genes and CRISPR array features were identified in 83% of the strains. Mapping the predicted spacers against the masked strain and RefSeq plasmid dataset identified 56,000 spacer-protospacer matches. While spacers mapped heavily to targets within bont(+) plasmids, no protospacers were identified within the bont gene clusters. These results indicate the toxin is not a direct target of CRISPR-Cas but the plasmids predominantly responsible for its mobilization are. Finally, while the presence of a CRISPR-Cas system did not reliably indicate the presence or absence of a bont gene cluster, comparative genomics across strains indicates they often occupy the same hypervariable loci common to both species, potentially suggesting similar mechanisms are involved in the acquisition and curation of both genomic features.
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Affiliation(s)
- Travis G. Wentz
- Microbiology Doctoral Training Program, University of Wisconsin–Madison, Madison, WI, United States,Division of Microbiology, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD, United States,Department of Bacteriology, University of Wisconsin–Madison, Madison, WI, United States
| | | | - Marite Bradshaw
- Department of Bacteriology, University of Wisconsin–Madison, Madison, WI, United States
| | - Andrew C. Doxey
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Shashi K. Sharma
- Division of Microbiology, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD, United States
| | - John-Demian Sauer
- Department of Medical Microbiology and Immunology, University of Wisconsin–Madison, Madison, WI, United States
| | - Sabine Pellett
- Department of Bacteriology, University of Wisconsin–Madison, Madison, WI, United States,*Correspondence: Sabine Pellett,
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17
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Current Developments in Diagnostic Assays for Laboratory Confirmation and Investigation of Botulism. J Clin Microbiol 2021; 60:e0013920. [PMID: 34586891 DOI: 10.1128/jcm.00139-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Detection of botulinum neurotoxin or isolation of the toxin producing organism is required for the laboratory confirmation of botulism in clinical specimens. In an effort to reduce animal testing required by the gold standard method of botulinum neurotoxin detection, the mouse bioassay, many technologies have been developed to detect and characterize the causative agent of botulism. Recent advancements in these technologies have led to improvements in technical performance of diagnostic assays; however, many emerging assays have not been validated for the detection of all serotypes in complex clinical and environmental matrices. Improvements to culture protocols, endopeptidase-based assays, and a variety of immunological and molecular methods have provided laboratories with a variety of testing options to evaluate and incorporate into their testing algorithms. While significant advances have been made to improve these assays, additional work is necessary to evaluate these methods in various clinical matrices and to establish standardized criteria for data analysis and interpretation.
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18
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Abstract
Botulinum neurotoxins (BoNTs) are the most toxic substances known to humankind and are the causative agents of the neuroparalytic disease botulism. Despite the overall importance of BoNTs in public health and safety, as a bioterrorism concern, and in pharmaceutical development, little is known about the molecular mechanisms mediating BoNT stability and degradation in various environments. Previous studies using Clostridium botulinum strain ATCC 3502 revealed that high levels of arginine (20 g/liter) repressed BoNT production approximately 1,000-fold. In the present study, the mechanisms of toxin reduction in arginine-enriched cultures of C. botulinum strain Hall A-hyper, which we have previously genetically manipulated using ClosTron technology, were explored. Cultures were grown in toxin production medium (TPM) and TPM enriched with arginine. Cultures were analyzed for growth (optical density at 600 nm [OD600]), changes in pH, and BoNT formation and stability. Our data indicate that arginine enrichment of C. botulinum strain Hall A-hyper cultures results in a pH shift that induces pH-dependent posttranslational control mechanisms. We further show that independent of arginine, maintenance of an acidic culture pH during growth of C. botulinum strain Hall A-hyper plays a central role in toxin stability and that an extracellular metalloprotease produced by the culture results in BoNT degradation at pH levels between ⁓6.5 and 8.0. IMPORTANCE Botulinum neurotoxin (BoNT) is a public health and bioterrorism concern as well as an important and widely used pharmaceutical, yet the regulation of its synthesis by BoNT-producing clostridia is not well understood. This paper highlights the role of environmentally controlled posttranslational regulatory mechanisms influencing processing and stability of biologically active BoNTs produced by C. botulinum. The results of this work will help enhance public health and safety measures and our ability to evaluate safety risks of novel BoNTs and improve production and quality of BoNTs for pharmaceutical use.
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19
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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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20
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Brunt J, van Vliet AHM, Carter AT, Stringer SC, Amar C, Grant KA, Godbole G, Peck MW. Diversity of the Genomes and Neurotoxins of Strains of Clostridium botulinum Group I and Clostridium sporogenes Associated with Foodborne, Infant and Wound Botulism. Toxins (Basel) 2020; 12:toxins12090586. [PMID: 32932818 PMCID: PMC7551954 DOI: 10.3390/toxins12090586] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 09/02/2020] [Accepted: 09/08/2020] [Indexed: 12/23/2022] Open
Abstract
Clostridium botulinum Group I and Clostridium sporogenes are closely related bacteria responsible for foodborne, infant and wound botulism. A comparative genomic study with 556 highly diverse strains of C. botulinum Group I and C. sporogenes (including 417 newly sequenced strains) has been carried out to characterise the genetic diversity and spread of these bacteria and their neurotoxin genes. Core genome single-nucleotide polymorphism (SNP) analysis revealed two major lineages; C. botulinum Group I (most strains possessed botulinum neurotoxin gene(s) of types A, B and/or F) and C. sporogenes (some strains possessed a type B botulinum neurotoxin gene). Both lineages contained strains responsible for foodborne, infant and wound botulism. A new C. sporogenes cluster was identified that included five strains with a gene encoding botulinum neurotoxin sub-type B1. There was significant evidence of horizontal transfer of botulinum neurotoxin genes between distantly related bacteria. Population structure/diversity have been characterised, and novel associations discovered between whole genome lineage, botulinum neurotoxin sub-type variant, epidemiological links to foodborne, infant and wound botulism, and geographic origin. The impact of genomic and physiological variability on the botulism risk has been assessed. The genome sequences are a valuable resource for future research (e.g., pathogen biology, evolution of C. botulinum and its neurotoxin genes, improved pathogen detection and discrimination), and support enhanced risk assessments and the prevention of botulism.
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Affiliation(s)
- Jason Brunt
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (A.T.C.); (S.C.S.)
- Correspondence: (J.B.); (M.W.P.)
| | - Arnoud H. M. van Vliet
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7AL, UK;
| | - Andrew T. Carter
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (A.T.C.); (S.C.S.)
| | - Sandra C. Stringer
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (A.T.C.); (S.C.S.)
| | - Corinne Amar
- Gastrointestinal Pathogens Unit, National Infection Service, Public Health England, London NW9 5EQ, UK; (C.A.); (K.A.G.); (G.G.)
| | - Kathie A. Grant
- Gastrointestinal Pathogens Unit, National Infection Service, Public Health England, London NW9 5EQ, UK; (C.A.); (K.A.G.); (G.G.)
| | - Gauri Godbole
- Gastrointestinal Pathogens Unit, National Infection Service, Public Health England, London NW9 5EQ, UK; (C.A.); (K.A.G.); (G.G.)
| | - Michael W. Peck
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (A.T.C.); (S.C.S.)
- Correspondence: (J.B.); (M.W.P.)
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21
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Brunt J, van Vliet AHM, Stringer SC, Carter AT, Lindström M, Peck MW. Pan-Genomic Analysis of Clostridium botulinum Group II (Non-Proteolytic C. botulinum) Associated with Foodborne Botulism and Isolated from the Environment. Toxins (Basel) 2020; 12:E306. [PMID: 32397147 PMCID: PMC7291236 DOI: 10.3390/toxins12050306] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 12/21/2022] Open
Abstract
The neurotoxin formed by Clostridium botulinum Group II is a major cause of foodborne botulism, a deadly intoxication. This study aims to understand the genetic diversity and spread of C. botulinum Group II strains and their neurotoxin genes. A comparative genomic study has been conducted with 208 highly diverse C. botulinum Group II strains (180 newly sequenced strains isolated from 16 countries over 80 years, 28 sequences from Genbank). Strains possessed a single type B, E, or F neurotoxin gene or were closely related strains with no neurotoxin gene. Botulinum neurotoxin subtype variants (including novel variants) with a unique amino acid sequence were identified. Core genome single-nucleotide polymorphism (SNP) analysis identified two major lineages-one with type E strains, and the second dominated by subtype B4 strains with subtype F6 strains. This study revealed novel details of population structure/diversity and established relationships between whole-genome lineage, botulinum neurotoxin subtype variant, association with foodborne botulism, epidemiology, and geographical source. Additionally, the genome sequences represent a valuable resource for the research community (e.g., understanding evolution of C. botulinum and its neurotoxin genes, dissecting key aspects of C. botulinum Group II biology). This may contribute to improved risk assessments and the prevention of foodborne botulism.
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Affiliation(s)
- Jason Brunt
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (S.C.S.); (A.T.C.)
| | - Arnoud H. M. van Vliet
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7AL, UK;
| | - Sandra C. Stringer
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (S.C.S.); (A.T.C.)
| | - Andrew T. Carter
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (S.C.S.); (A.T.C.)
| | - Miia Lindström
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, 00014 Helsinki, Finland;
| | - Michael W. Peck
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (S.C.S.); (A.T.C.)
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22
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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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23
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The Novel Clostridial Neurotoxin Produced by Strain IBCA10-7060 Is Immunologically Equivalent to BoNT/HA. Toxins (Basel) 2019; 12:toxins12010009. [PMID: 31877649 PMCID: PMC7020490 DOI: 10.3390/toxins12010009] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/07/2019] [Accepted: 12/12/2019] [Indexed: 11/16/2022] Open
Abstract
Background: Botulinum neurotoxins (BoNTs) comprise seven agreed-on serotypes, A through G. In 2014, a novel chimeric neurotoxin produced by clostridial strain IBCA10-7060 was reported as BoNT/H, with subsequent names of BoNT/FA or BoNT/HA based on sequence homology of the N-terminus to BoNT/F, the C-terminus to BoNT/A and neutralization studies. The purpose of this study was to define the immunologic identity of the novel BoNT. Methods: monoclonal antibodies (mAbs) to the novel BoNT/H N-terminus were generated by antibody repertoire cloning and yeast display after immunization with BoNT/H LC-HN or BoNT/F LC-HN. Results: 21 unique BoNT/H LC-HN mAbs were obtained; 15 from the BoNT/H LC-HN immunized library (KD 0.78 nM to 182 nM) and six from the BoNT/F-immunized libraries (KD 20.5 nM to 1490 nM). A total of 15 of 21 mAbs also bound catalytically inactive BoNT/H holotoxin. The mAbs bound nine non-overlapping epitopes on the BoNT/H LC-HN. None of the mAbs showed binding to BoNT serotypes A-G, nor any of the seven subtypes of BoNT/F, except for one mAb that weakly bound BoNT/F5. Conclusions: The results, combined with the chimeric structure and neutralization by anti-A, but not anti-F antitoxin indicate that immunologically the novel BoNT is BoNT/HA. This determination has significant implications for existing countermeasures and potential vulnerabilities.
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Martínez-Carranza M, Blasco P, Gustafsson R, Dong M, Berntsson RPA, Widmalm G, Stenmark P. Synaptotagmin Binding to Botulinum Neurotoxins. Biochemistry 2019; 59:491-498. [PMID: 31809018 DOI: 10.1021/acs.biochem.9b00554] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Botulinum neurotoxins (BoNTs) are exceptionally toxic proteins that cause paralysis but are also extensively used as treatment for various medical conditions. Most BoNTs bind two receptors on neuronal cells, namely, a ganglioside and a protein receptor. Differences in the sequence between the protein receptors from different species can impact the binding affinity and toxicity of the BoNTs. Here we have investigated how BoNT/B, /DC, and /G, all three toxins that utilize synaptotagmin I and II (Syt-I and Syt-II, respectively) as their protein receptors, bind to Syt-I and -II of mouse/rat, bovine, and human origin by isothermal titration calorimetry analysis. BoNT/G had the highest affinity for human Syt-I, and BoNT/DC had the highest affinity for bovine Syt-II. As expected, BoNT/B, /DC, and /G showed very low levels of binding to human Syt-II. Furthermore, we carried out saturation transfer difference (STD) and STD-TOCSY NMR experiments that revealed the region of the Syt peptide in direct contact with BoNT/G, which demonstrate that BoNT/G recognizes the Syt peptide in a model similar to that in the established BoNT/B-Syt-II complex. Our analyses also revealed that regions outside the Syt peptide's toxin-binding region are important for the helicity of the peptide and, therefore, the binding affinity.
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Affiliation(s)
| | - Pilar Blasco
- Department of Organic Chemistry , Stockholm University , SE-106 91 Stockholm , Sweden
| | - Robert Gustafsson
- Department of Biochemistry and Biophysics , Stockholm University , SE-106 91 Stockholm , Sweden
| | - Min Dong
- Department of Urology, Boston's Children Hospital, and Department of Microbiology and Immunology and Department of Surgery , Harvard Medical School , Boston , Massachusetts 02115 , United States
| | - Ronnie Per-Arne Berntsson
- Department of Medical Biochemistry and Biophysics , Umeå University , SE-90187 Umeå , Sweden.,Wallenberg Centre for Molecular Medicine , Umeå University , SE-90187 Umeå , Sweden
| | - Göran Widmalm
- Department of Organic Chemistry , Stockholm University , SE-106 91 Stockholm , Sweden
| | - 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
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Pellett S, Tepp WH, Johnson EA. Critical Analysis of Neuronal Cell and the Mouse Bioassay for Detection of Botulinum Neurotoxins. Toxins (Basel) 2019; 11:E713. [PMID: 31817843 PMCID: PMC6950160 DOI: 10.3390/toxins11120713] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 11/12/2019] [Accepted: 11/22/2019] [Indexed: 12/14/2022] Open
Abstract
Botulinum Neurotoxins (BoNTs) are a large protein family that includes the most potent neurotoxins known to humankind. BoNTs delivered locally in humans at low doses are widely used pharmaceuticals. Reliable and quantitative detection of BoNTs is of paramount importance for the clinical diagnosis of botulism, basic research, drug development, potency determination, and detection in clinical, environmental, and food samples. Ideally, a definitive assay for BoNT should reflect the activity of each of the four steps in nerve intoxication. The in vivo mouse bioassay (MBA) is the 'gold standard' for the detection of BoNTs. The MBA is sensitive, robust, semi-quantitative, and reliable within its sensitivity limits. Potential drawbacks with the MBA include assay-to-assay potency variations, especially between laboratories, and false positives or negatives. These limitations can be largely avoided by careful planning and performance. Another detection method that has gained importance in recent years for research and potency determination of pharmaceutical BoNTs is cell-based assays, as these assays can be highly sensitive, quantitative, human-specific, and detect fully functional holotoxins at physiologically relevant concentrations. A myriad of other in vitro BoNT detection methods exist. This review focuses on critical factors and assay limitations of the mouse bioassay and cell-based assays for BoNT detection.
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Affiliation(s)
| | | | - Eric A. Johnson
- Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA; (S.P.); (W.H.T.)
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Moritz MS, Tepp WH, Inzalaco HN, Johnson EA, Pellett S. Comparative functional analysis of mice after local injection with botulinum neurotoxin A1, A2, A6, and B1 by catwalk analysis. Toxicon 2019; 167:20-28. [PMID: 31181297 PMCID: PMC6688953 DOI: 10.1016/j.toxicon.2019.06.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 05/20/2019] [Accepted: 06/03/2019] [Indexed: 01/10/2023]
Abstract
Botulinum neurotoxins (BoNTs) are potent neurotoxins and are the causative agent of botulism, as well as valuable pharmaceuticals. BoNTs are divided into seven serotypes that comprise over 40 reported subtypes. BoNT/A1 and BoNT/B1 are currently the only subtypes approved for pharmaceutical use in the USA. While several other BoNT subtypes including BoNT/A2 and/A6 have been proposed as promising pharmaceuticals, detailed characterization using in vivo assays are essential to determine their pharmaceutical characteristics compared to the currently used BoNT/A1 and/B1. Several methods for studying BoNTs in mice are being used, but no objective and quantitative assay for assessment of functional outcomes after injection has been described. Here we describe the use of CatWalk XT as a new analytical tool for the objective and quantitative analysis of the paralytic effect after local intramuscular injection of BoNT subtypes A1, A2, A6, and B1. Catwalk is a sophisticated gait and locomotion analysis system that quantitatively analyzes a rodent's paw print dimensions and footfall patterns while traversing a glass plate during unforced walk. Significant changes were observed in several gait parameters in mice after local intramuscular injection of all tested BoNT subtypes, however, no changes were observed in mice injected intraperitoneally with the same BoNTs. While a clear difference in time to peak paralysis was observed between BoNT/A1 and/B1, injection of all four toxins resulted in a deficit in the injected limb with the other limbs functionally compensating and with no qualitative differences between the four BoNT subtypes. The presented data demonstrate the utility of CatWalk as a tool for functional outcomes after local BoNT injection through its ability to collect large amounts of quantitative data and objectively analyze sensitive changes in static and dynamic gait parameters.
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Affiliation(s)
- Molly S Moritz
- University of Wisconsin-Madison, Dept. of Bacteriology, USA
| | - William H Tepp
- University of Wisconsin-Madison, Dept. of Bacteriology, USA
| | | | - Eric A Johnson
- University of Wisconsin-Madison, Dept. of Bacteriology, USA
| | - Sabine Pellett
- University of Wisconsin-Madison, Dept. of Bacteriology, USA.
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Revitt-Mills SA, Vidor CJ, Watts TD, Lyras D, Rood JI, Adams V. Virulence Plasmids of the Pathogenic Clostridia. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0034-2018. [PMID: 31111816 PMCID: PMC11257192 DOI: 10.1128/microbiolspec.gpp3-0034-2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Indexed: 12/12/2022] Open
Abstract
The clostridia cause a spectrum of diseases in humans and animals ranging from life-threatening tetanus and botulism, uterine infections, histotoxic infections and enteric diseases, including antibiotic-associated diarrhea, and food poisoning. The symptoms of all these diseases are the result of potent protein toxins produced by these organisms. These toxins are diverse, ranging from a multitude of pore-forming toxins to phospholipases, metalloproteases, ADP-ribosyltransferases and large glycosyltransferases. The location of the toxin genes is the unifying theme of this review because with one or two exceptions they are all located on plasmids or on bacteriophage that replicate using a plasmid-like intermediate. Some of these plasmids are distantly related whilst others share little or no similarity. Many of these toxin plasmids have been shown to be conjugative. The mobile nature of these toxin genes gives a ready explanation of how clostridial toxin genes have been so widely disseminated both within the clostridial genera as well as in the wider bacterial community.
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Affiliation(s)
- Sarah A Revitt-Mills
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Callum J Vidor
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Thomas D Watts
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Dena Lyras
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Julian I Rood
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Vicki Adams
- Infection and Immunity Program, Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
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Poulain B, Popoff MR. Why Are Botulinum Neurotoxin-Producing Bacteria So Diverse and Botulinum Neurotoxins So Toxic? Toxins (Basel) 2019; 11:toxins11010034. [PMID: 30641949 PMCID: PMC6357194 DOI: 10.3390/toxins11010034] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 01/03/2019] [Accepted: 01/09/2019] [Indexed: 12/15/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are the most lethal toxins among all bacterial, animal, plant and chemical poisonous compounds. Although a great effort has been made to understand their mode of action, some questions are still open. Why, and for what benefit, have environmental bacteria that accidentally interact with their host engineered so diverse and so specific toxins targeting one of the most specialized physiological processes, the neuroexocytosis of higher organisms? The extreme potency of BoNT does not result from only one hyperactive step, but in contrast to other potent lethal toxins, from multi-step activity. The cumulative effects of the different steps, each having a limited effect, make BoNTs the most potent lethal toxins. This is a unique mode of evolution of a toxic compound, the high potency of which results from multiple steps driven by unknown selection pressure, targeting one of the most critical physiological process of higher organisms.
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Affiliation(s)
- Bernard Poulain
- Institut des Neurosciences Cellulaires et Intégratives, (INCI)-CNRS, UPR 3212 Strasbourg, France.
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Evander Emeltan Tjoa S, Maria Vianney Y, Emantoko Dwi Putra S. In silico mutagenesis: decreasing the immunogenicity of botulinum toxin type A. J Biomol Struct Dyn 2018; 37:4767-4778. [PMID: 30558486 DOI: 10.1080/07391102.2018.1559100] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Botulinum toxin serotype A is a prominent therapeutic enzyme, for both clinical and cosmetic uses. Since this protein is produced by bacteria, it exhibits an allergenic effect when subjected to human therapy. Protein mutagenesis is one method to improve the characteristics of protein. However, in silico study is needed to give suggestion of which amino acid should be mutated. Hence, a lot of money and time can be saved. This study initially screened which residue of the Botulinum toxin serotype A is B-cell epitopes both linearly and conformationally. By overlapping the B-cell epitopes with the excluded conserve sequence, seven residues were allowed to be mutated. There were two proposed muteins showing a reduction in the antigenicity probability: ΔE147, E510F, T1062F, ΔE1080, N1089M and ΔQ1090; and ΔE147, E510F, T1062F, E1080W, N1089M and ΔQ1090. Molecular dynamics simulation of the 3D proposed muteins indicated an increase of flexibility in both muteins compared to that in the native protein. Both muteins have lower antigenicity. In addition, they are similar in structure, stability and functionality compared to the native protein.
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Affiliation(s)
| | - Yoanes Maria Vianney
- Faculty of Biotechnology, University of Surabaya , Surabaya , East Java , Indonesia
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Tam CC, Flannery AR, Cheng LW. A Rapid, Sensitive, and Portable Biosensor Assay for the Detection of Botulinum Neurotoxin Serotype A in Complex Food Matrices. Toxins (Basel) 2018; 10:toxins10110476. [PMID: 30445734 PMCID: PMC6266793 DOI: 10.3390/toxins10110476] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 11/09/2018] [Accepted: 11/12/2018] [Indexed: 12/14/2022] Open
Abstract
Botulinum neurotoxin (BoNT) intoxication can lead to the disease botulism, characterized by flaccid muscle paralysis that can cause respiratory failure and death. Due to the significant morbidity and mortality costs associated with BoNTs high toxicity, developing highly sensitive, rapid, and field-deployable assays are critically important to protect the nation’s food supply against either accidental or intentional contamination. We report here that the B-cell based biosensor assay CANARY® (Cellular Analysis and Notification of Antigen Risks and Yields) Zephyr detects BoNT/A holotoxin at limits of detection (LOD) of 10.0 ± 2.5 ng/mL in assay buffer. Milk matrices (whole milk, 2% milk and non-fat milk) with BoNT/A holotoxin were detected at similar levels (7.4–7.9 ng/mL). BoNT/A complex was positive in carrot, orange, and apple juices at LODs of 32.5–75.0 ng/mL. The detection of BoNT/A complex in solid complex foods (ground beef, smoked salmon, green bean baby puree) ranged from 14.8 ng/mL to 62.5 ng/mL. Detection of BoNT/A complex in the viscous liquid egg matrix required dilution in assay buffer and gave a LOD of 171.9 ± 64.7 ng/mL. These results show that the CANARY® Zephyr assay can be a highly useful qualitative tool in environmental and food safety surveillance programs.
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Affiliation(s)
- Christina C Tam
- Foodborne Toxin Detection and Prevention Research Unit, Western Regional Research Center, Agricultural Research Services, United States Department of Agriculture, 800 Buchanan Street, Albany, CA 94710, USA.
| | | | - Luisa W Cheng
- Foodborne Toxin Detection and Prevention Research Unit, Western Regional Research Center, Agricultural Research Services, United States Department of Agriculture, 800 Buchanan Street, Albany, CA 94710, USA.
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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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Chellapandi P, Prisilla A. PCR-based molecular diagnosis of botulism (types C and D) outbreaks in aquatic birds. ANN MICROBIOL 2018. [DOI: 10.1007/s13213-018-1390-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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Benoit RM. Botulinum Neurotoxin Diversity from a Gene-Centered View. Toxins (Basel) 2018; 10:E310. [PMID: 30071587 PMCID: PMC6115791 DOI: 10.3390/toxins10080310] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 07/24/2018] [Accepted: 07/30/2018] [Indexed: 12/16/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) rank amongst the most potent toxins known. The factors responsible for the emergence of the many known and yet unknown BoNT variants remain elusive. It also remains unclear why anaerobic bacteria that are widely distributed in our environment and normally do not pose a threat to humans, produce such deadly toxins. Even the possibility of accidental toxicity to humans has not been excluded. Here, I review the notion that BoNTs may have specifically evolved to target vertebrates. Considering the extremely complex molecular architecture of the toxins, which enables them to reach the bloodstream, to recognize and enter neurons, and to block neurotransmitter release, it seems highly unlikely that BoNT toxicity to vertebrates is a coincidence. The carcass⁻maggot cycle provides a plausible explanation for a natural role of the toxins: to enable mass reproduction of bacteria, spores, and toxins, using toxin-unaffected invertebrates, such as fly maggots, as the vectors. There is no clear correlation between toxigenicity and a selective advantage of clostridia in their natural habitat. Possibly, non-toxigenic strains profit from carcasses resulting from the action of toxigenic strains. Alternatively, a gene-centered view of toxin evolution would also explain this observation. Toxin-coding mobile genetic elements may have evolved as selfish genes, promoting their own propagation, similar to commensal viruses, using clostridia and other bacteria as the host. Research addressing the role of BoNTs in nature and the origin of toxin variability goes hand in hand with the identification of new toxin variants and the design of improved toxin variants for medical applications. These research directions may also reveal yet unknown natural antidotes against these extremely potent neurotoxins.
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Affiliation(s)
- Roger M Benoit
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institute, Villigen CH-5232, Switzerland.
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Webb RP. Engineering of Botulinum Neurotoxins for Biomedical Applications. Toxins (Basel) 2018; 10:toxins10060231. [PMID: 29882791 PMCID: PMC6024800 DOI: 10.3390/toxins10060231] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 06/01/2018] [Accepted: 06/05/2018] [Indexed: 01/15/2023] Open
Abstract
Botulinum neurotoxins (BoNTs) have been used as therapeutic agents in the clinical treatment of a wide array of neuromuscular and autonomic neuronal transmission disorders. These toxins contain three functional domains that mediate highly specific neuronal cell binding, internalization and cytosolic delivery of proteolytic enzymes that cleave proteins integral to the exocytosis of neurotransmitters. The exceptional cellular specificity, potency and persistence within the neuron that make BoNTs such effective toxins, also make them attractive models for derivatives that have modified properties that could potentially expand their therapeutic repertoire. Advances in molecular biology techniques and rapid DNA synthesis have allowed a wide variety of novel BoNTs with alternative functions to be assessed as potential new classes of therapeutic drugs. This review examines how the BoNTs have been engineered in an effort to produce new classes of therapeutic molecules to address a wide array of disorders.
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Affiliation(s)
- Robert P Webb
- The Division of Molecular and Translational Sciences, United States Army Medical Research Institute for Infectious Diseases, Fort Detrick, MD 21702, USA.
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The orphan germinant receptor protein GerXAO (but not GerX3b) is essential for L-alanine induced germination in Clostridium botulinum Group II. Sci Rep 2018; 8:7060. [PMID: 29728678 PMCID: PMC5935672 DOI: 10.1038/s41598-018-25411-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 04/20/2018] [Indexed: 12/27/2022] Open
Abstract
Clostridium botulinum is an anaerobic spore forming bacterium that produces the potent botulinum neurotoxin that causes a severe and fatal neuro-paralytic disease of humans and animals (botulism). C. botulinum Group II is a psychrotrophic saccharolytic bacterium that forms spores of moderate heat resistance and is a particular hazard in minimally heated chilled foods. Spore germination is a fundamental process that allows the spore to transition to a vegetative cell and typically involves a germinant receptor (GR) that responds to environmental signals. Analysis of C. botulinum Group II genomes shows they contain a single GR cluster (gerX3b), and an additional single gerA subunit (gerXAO). Spores of C. botulinum Group II strain Eklund 17B germinated in response to the addition of L-alanine, but did not germinate following the addition of exogenous Ca2+-DPA. Insertional inactivation experiments in this strain unexpectedly revealed that the orphan GR GerXAO is essential for L-alanine stimulated germination. GerX3bA and GerX3bC affected the germination rate but were unable to induce germination in the absence of GerXAO. No role could be identified for GerX3bB. This is the first study to identify the functional germination receptor of C. botulinum Group II.
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Abstract
Botulinum neurotoxin (BoNT) is the causative agent of botulism and a widely used pharmaceutical to treat a variety of neurological diseases. BoNTs are 150-kDa protein toxins organized into heavy chain (HC) and light chain (LC) domains linked by a disulfide bond. The HC selectively binds to neurons and aids cell entry of the enzymatically active LC. There are seven immunological BoNT serotypes (A to G); each serotype includes genetic variants, termed subtypes. Only two subtypes, BoNT/A1 and BoNT/B1, are currently used as therapeutics. BoNT serotype A (BoNT/A) subtypes A2 to A8 show distinct potency, duration of action, and pathology relative to BoNT/A1. Specifically, BoNT/A3 possesses shorter duration of action and elicits distinct symptoms in mice at high toxin doses. In this report, we analyzed the roles of LC and HC of BoNT/A3 for duration of action, neuronal cell entry, and mouse pathology by using clostridium-derived recombinant hybrid BoNTs consisting of reciprocal LC and HC (BoNTA1/A3 and BoNTA3/A1). Hybrid toxins were processed in their expression host to a dichain BoNT consisting of LC and HC linked via a disulfide bond. The LC and HC defined BoNT potency in mice and BoNT toxicity for cultured neuronal cells, while the LC defined the duration of BoNT action in cell and mouse models. Protein alignment identified a previously unrecognized region within the LC subtype A3 (LC/A3) relative to the other LC serotype A (LC/A) subtypes (low primary acid homology [LPH]) that correlated to intracellular LC localization. This study shows the utility of recombinant hybrid BoNTs with new therapeutic potential, while remaining sensitive to antitoxins and therapies to native BoNT. Botulinum neurotoxins are the most potent protein toxins for humans and potential bioterrorism threats, but they are also widely used as pharmaceuticals. Within the large family of BoNTs, only two subtypes are currently used as pharmaceuticals, with a large number of BoNT subtypes remaining as untapped potential sources for unique pharmaceuticals. Here, two recombinant hybrid toxins were engineered, consisting of domains from two BoNT subtypes that possess distinct duration of action and activity in human neurons and mice. We define the functional domains responsible for BoNT action and demonstrate creation of functional hybrid BoNTs with new therapeutic potential, while remaining sensitive to antitoxins and therapies to native BoNT.
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Brunt J, Carter AT, Stringer SC, Peck MW. Identification of a novel botulinum neurotoxin gene cluster in Enterococcus. FEBS Lett 2018; 592:310-317. [PMID: 29323697 PMCID: PMC5838542 DOI: 10.1002/1873-3468.12969] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 12/28/2017] [Accepted: 01/02/2018] [Indexed: 01/02/2023]
Abstract
The deadly neurotoxins of Clostridium botulinum (BoNTs) comprise eight serotypes (A-G; X). The neurotoxin gene cluster encoding BoNT and its accessory proteins includes an operon containing an ntnh gene upstream of the boNT gene. Another operon contains either ha (haemagglutinin) or orfX genes (of unknown function). Here we describe a novel boNT gene cluster from Enterococcus sp. 3G1_DIV0629, with a typical ntnh gene and an uncommon orfX arrangement. The neurotoxin (designated putative eBoNT/J) contains a metallopeptidase zinc-binding site, a translocation domain and a target cell attachment domain. Structural properties of the latter suggest a novel targeting mechanism with consequent implications for application by the pharmaceutical industry. This is the first complete boNT gene cluster identified in a non-clostridial genome.
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Affiliation(s)
- Jason Brunt
- Gut Health and Food SafetyQuadram InstituteNorwichUK
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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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Abstract
Though seemingly distinct and autonomous, emerging evidence suggests there is a bidirectional interaction between the intestinal microbiota and the brain. This crosstalk may play a substantial role in neurologic diseases, including anxiety, depression, autism, multiple sclerosis, Parkinson's disease, and, potentially, Alzheimer's disease. Long hypothesized by Metchnikoff and others well over 100 years ago, investigations into the mind-microbe axis is now seeing a rapid resurgence of research. If specific pathways and mechanisms of interaction are understood, it could have broad therapeutic potential, as the microbiome is environmentally acquired and can be modified to promote health. This review will discuss immune, endocrine, and neural system pathways that interconnect the gut microbiota to central nervous system and discuss how these findings might be applied to neurologic disease.
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Affiliation(s)
- Laura M Cox
- Ann Romney Center for Neurologic Diseases, Brigham & Women's Hospital, Harvard Medical School, 60 Fenwood Road, Boston, MA, 02446, USA
| | - Howard L Weiner
- Ann Romney Center for Neurologic Diseases, Brigham & Women's Hospital, Harvard Medical School, 60 Fenwood Road, Boston, MA, 02446, USA.
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41
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Pellett S, Tepp WH, Lin G, Johnson EA. Substrate cleavage and duration of action of botulinum neurotoxin type FA ("H, HA"). Toxicon 2017; 147:38-46. [PMID: 29273248 PMCID: PMC5911199 DOI: 10.1016/j.toxicon.2017.12.048] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 12/15/2017] [Accepted: 12/18/2017] [Indexed: 12/12/2022]
Abstract
Botulinum neurotoxin (BoNT) type FA is the only known naturally occurring chimeric BoNT of domains of BoNT/A and BoNT/F. BoNT/FA consists of an F5-like light chain (LC), a unique heavy chain (HC) translocation domain, and a HC receptor binding domain similar to BoNT/A1. Previous analyses of purified BoNT/FA have indicated a 5-10-fold greater potency in cultured human or rat neurons as compared to BoNT/A1 and a 400-500-fold greater potency compared to BoNT/B1. However, in vivo potency in mice was about 5-fold lower than BoNT/A1 or/B1. In this report, species specificity was examined by cell-based assays using primary neurons from mice and examining VAMP1 and 2 cleavage. The data indicated similar potency of BoNT/FA in primary mouse spinal cord neurons as previously observed in primary rat and human induced pluripotent stem cell (hiPSC) derived neuronal cell models, and equal enzymatic cleavage of mouse VAMP1 and 2 isoforms. Since the duration of action of BoNTs is due to continuous enzymatic activity of the LC in the neuronal cytosol, BoNT/FA was expected to have a short duration of action due to its F-type LC. In this report the duration of action of BoNT/FA was compared to that of BoNT/F1,/F5, and/B1 in both hiPSC derived neurons and in the in vivo mouse model. The data indicate a duration of action of BoNT/FA similar to BoNT/B1, while BoNT/F5 had a short duration of action similar to BoNT/F1.
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Affiliation(s)
- Sabine Pellett
- Department of Bacteriology, University of Wisconsin, 1550 Linden Dr., Madison, WI 53706, USA.
| | - William H Tepp
- Department of Bacteriology, University of Wisconsin, 1550 Linden Dr., Madison, WI 53706, USA.
| | - Guangyun Lin
- Department of Bacteriology, University of Wisconsin, 1550 Linden Dr., Madison, WI 53706, USA.
| | - Eric A Johnson
- Department of Bacteriology, University of Wisconsin, 1550 Linden Dr., Madison, WI 53706, USA.
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42
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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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43
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Investigating CRISPR-Cas systems in Clostridium botulinum via bioinformatics tools. INFECTION GENETICS AND EVOLUTION 2017; 54:355-373. [DOI: 10.1016/j.meegid.2017.06.027] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 06/19/2017] [Accepted: 06/27/2017] [Indexed: 12/22/2022]
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44
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Vaccines against Botulism. Toxins (Basel) 2017; 9:toxins9090268. [PMID: 28869493 PMCID: PMC5618201 DOI: 10.3390/toxins9090268] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 08/30/2017] [Accepted: 08/30/2017] [Indexed: 12/16/2022] Open
Abstract
Botulinum neurotoxins (BoNT) cause the flaccid paralysis of botulism by inhibiting the release of acetylcholine from motor neurons. There are seven serotypes of BoNT (A-G), with limited therapies, and no FDA approved vaccine for botulism. An investigational formalin-inactivated penta-serotype-BoNT/A-E toxoid vaccine was used to vaccinate people who are at high risk of contracting botulism. However, this formalin-inactivated penta-serotype-BoNT/A-E toxoid vaccine was losing potency and was discontinued. This article reviews the different vaccines being developed to replace the discontinued toxoid vaccine. These vaccines include DNA-based, viral vector-based, and recombinant protein-based vaccines. DNA-based vaccines include plasmids or viral vectors containing the gene encoding one of the BoNT heavy chain receptor binding domains (HC). Viral vectors reviewed are adenovirus, influenza virus, rabies virus, Semliki Forest virus, and Venezuelan Equine Encephalitis virus. Among the potential recombinant protein vaccines reviewed are HC, light chain-heavy chain translocation domain, and chemically or genetically inactivated holotoxin.
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45
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Cohen JE, Wang R, Shen RF, Wu WW, Keller JE. Comparative pathogenomics of Clostridium tetani. PLoS One 2017; 12:e0182909. [PMID: 28800585 PMCID: PMC5553647 DOI: 10.1371/journal.pone.0182909] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 07/26/2017] [Indexed: 01/27/2023] Open
Abstract
Clostridium tetani and Clostridium botulinum produce two of the most potent neurotoxins known, tetanus neurotoxin and botulinum neurotoxin, respectively. Extensive biochemical and genetic investigation has been devoted to identifying and characterizing various C. botulinum strains. Less effort has been focused on studying C. tetani likely because recently sequenced strains of C. tetani show much less genetic diversity than C. botulinum strains and because widespread vaccination efforts have reduced the public health threat from tetanus. Our aim was to acquire genomic data on the U.S. vaccine strain of C. tetani to better understand its genetic relationship to previously published genomic data from European vaccine strains. We performed high throughput genomic sequence analysis on two wild-type and two vaccine C. tetani strains. Comparative genomic analysis was performed using these and previously published genomic data for seven other C. tetani strains. Our analysis focused on single nucleotide polymorphisms (SNP) and four distinct constituents of the mobile genome (mobilome): a hypervariable flagellar glycosylation island region, five conserved bacteriophage insertion regions, variations in three CRISPR (clustered regularly interspaced short palindromic repeats)-Cas (CRISPR-associated) systems, and a single plasmid. Intact type IA and IB CRISPR/Cas systems were within 10 of 11 strains. A type IIIA CRISPR/Cas system was present in two strains. Phage infection histories derived from CRISPR-Cas sequences indicate C. tetani encounters phages common among commensal gut bacteria and soil-borne organisms consistent with C. tetani distribution in nature. All vaccine strains form a clade distinct from currently sequenced wild type strains when considering variations in these mobile elements. SNP, flagellar glycosylation island, prophage content and CRISPR/Cas phylogenic histories provide tentative evidence suggesting vaccine and wild type strains share a common ancestor.
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Affiliation(s)
- Jonathan E. Cohen
- Laboratory of Respiratory and Special Pathogens, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Rong Wang
- Facility for Biotechnology Resources, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Rong-Fong Shen
- Facility for Biotechnology Resources, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Wells W. Wu
- Facility for Biotechnology Resources, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - James E. Keller
- Laboratory of Respiratory and Special Pathogens, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
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46
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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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47
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Tao L, Peng L, Berntsson RPA, Liu SM, Park S, Yu F, Boone C, Palan S, Beard M, Chabrier PE, Stenmark P, Krupp J, Dong M. Engineered botulinum neurotoxin B with improved efficacy for targeting human receptors. Nat Commun 2017; 8:53. [PMID: 28674381 PMCID: PMC5495808 DOI: 10.1038/s41467-017-00064-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 04/26/2017] [Indexed: 11/25/2022] Open
Abstract
Botulinum neurotoxin B is a Food and Drug Administration-approved therapeutic toxin. However, it has lower binding affinity toward the human version of its major receptor, synaptotagmin II (h-Syt II), compared to mouse Syt II, because of a residue difference. Increasing the binding affinity to h-Syt II may improve botulinum neurotoxin B’s therapeutic efficacy and reduce adverse effects. Here we utilized the bacterial adenylate cyclase two-hybrid method and carried out a saturation mutagenesis screen in the Syt II-binding pocket of botulinum neurotoxin B. The screen identifies E1191 as a key residue: replacing it with M/C/V/Q enhances botulinum neurotoxin B binding to human synaptotagmin II. Adding S1199Y/W or W1178Q as a secondary mutation further increases binding affinity. Mutant botulinum neurotoxin B containing E1191M/S1199Y exhibits ~11-fold higher efficacy in blocking neurotransmission than wild-type botulinum neurotoxin B in neurons expressing human synaptotagmin II, demonstrating that enhancing receptor binding increases the overall efficacy at functional levels. The engineered botulinum neurotoxin B provides a platform to develop therapeutic toxins with improved efficacy. Humans are less sensitive to the therapeutic effects of botulinum neurotoxin B (BoNT/B) than the animal models it is tested on due to differences between the human and the mouse receptors. Here, the authors engineer BoNT/B to improve its affinity to human receptors and enhance its therapeutic efficacy.
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Affiliation(s)
- Liang Tao
- Department of Urology, Boston Children's Hospital, Department of Microbiology and Immunobiology, Department of Surgery, Harvard Medical School, 300 Longwood Avenue, Boston, Massachusetts, 02115, USA
| | - Lisheng Peng
- Department of Urology, Boston Children's Hospital, Department of Microbiology and Immunobiology, Department of Surgery, Harvard Medical School, 300 Longwood Avenue, Boston, Massachusetts, 02115, USA.,Department of Neurology, The Third Affiliated Hospital of Sun Yat-sen University, No. 600 Tianhe Road, Guangzhou, Guangdong, 510630, China
| | - Ronnie P-A Berntsson
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, SE-106 91, Sweden.,Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, SE-901 87, Sweden
| | | | - SunHyun Park
- Department of Urology, Boston Children's Hospital, Department of Microbiology and Immunobiology, Department of Surgery, Harvard Medical School, 300 Longwood Avenue, Boston, Massachusetts, 02115, USA.,Division of Predictive Toxicological Research, Predictive model Research Center, Korea Institute of Toxicology, 141 Gajeong-ro, Yuseong-gu, Daejeon, 34114, South Korea
| | - Feifan Yu
- Department of Urology, Boston Children's Hospital, Department of Microbiology and Immunobiology, Department of Surgery, Harvard Medical School, 300 Longwood Avenue, Boston, Massachusetts, 02115, USA
| | - Christopher Boone
- Department of Urology, Boston Children's Hospital, Department of Microbiology and Immunobiology, Department of Surgery, Harvard Medical School, 300 Longwood Avenue, Boston, Massachusetts, 02115, USA
| | | | | | | | - Pål Stenmark
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, SE-106 91, Sweden.
| | - Johannes Krupp
- IPSEN Bioinnovation, Abingdon, OX14 4RY, UK. .,IPSEN Innovation, Les Ulis, 91940, France.
| | - Min Dong
- Department of Urology, Boston Children's Hospital, Department of Microbiology and Immunobiology, Department of Surgery, Harvard Medical School, 300 Longwood Avenue, Boston, Massachusetts, 02115, USA.
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48
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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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49
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Characterization of Clostridium Baratii Type F Strains Responsible for an Outbreak of Botulism Linked to Beef Meat Consumption in France. PLOS CURRENTS 2017; 9. [PMID: 29862134 PMCID: PMC5959735 DOI: 10.1371/currents.outbreaks.6ed2fe754b58a5c42d0c33d586ffc606] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Introduction: A second botulism outbreak due to Clostridium baratii occurred in France in August 2015 and included three patients who had their meal in a restaurant the same day. We report the characterization of C. baratii isolates including whole genome sequencing (WGS). Methods: Four C. baratii isolates collected in August 2015 from the outbreak 2 were analysed for toxin production and typing as well as for genetic characterization. WGS was done using using the NEBNext Ultra DNA Library Prep kit for Illumina (New England Biolabs) and sequenced on MiSeq machine (Illumina) in paired-end reads of 250 bases. The phylogenetic tree was generated based on the UPGMA method with genetic distances computed by using the Kimura two-parameter model. Evolutionary analyses were conducted in Bionumerics (V.6.6 Applied Maths). Results: Three C. baratii isolates for patient's stools and one isolate from meat produced botulinum neurotoxin (BoNT) type F and retained a bont/F7 gene in OrfX cluster. All isolates were identical according to the WGS. However, phylogeny of the core genome showed that the four C. baratii strains were distantly related to that of the previous C. baratii outbreak in France in 2014 and from the other C. baratii strains reported in databanks. Discussion: The fact that the strains isolated from the patients and meat samples were genetically identical supports that the meat used for the Bolognese sauce was responsible for this second botulism outbreak in France. These isolates were unrelated to that from the first C. baratii outbreak in France in 2014 indicating a distinct source of contamination. WGS provided robust determination of genetic relatedness and information regarding BoNT typing and toxin gene locus genomic localization.
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50
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Peck MW, Smith TJ, Anniballi F, Austin JW, Bano L, Bradshaw M, Cuervo P, Cheng LW, Derman Y, Dorner BG, Fisher A, Hill KK, Kalb SR, Korkeala H, Lindström M, Lista F, Lúquez C, Mazuet C, Pirazzini M, Popoff MR, Rossetto O, Rummel A, Sesardic D, Singh BR, Stringer SC. Historical Perspectives and Guidelines for Botulinum Neurotoxin Subtype Nomenclature. Toxins (Basel) 2017; 9:toxins9010038. [PMID: 28106761 PMCID: PMC5308270 DOI: 10.3390/toxins9010038] [Citation(s) in RCA: 187] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 01/04/2017] [Accepted: 01/07/2017] [Indexed: 11/26/2022] Open
Abstract
Botulinum neurotoxins are diverse proteins. They are currently represented by at least seven serotypes and more than 40 subtypes. New clostridial strains that produce novel neurotoxin variants are being identified with increasing frequency, which presents challenges when organizing the nomenclature surrounding these neurotoxins. Worldwide, researchers are faced with the possibility that toxins having identical sequences may be given different designations or novel toxins having unique sequences may be given the same designations on publication. In order to minimize these problems, an ad hoc committee consisting of over 20 researchers in the field of botulinum neurotoxin research was convened to discuss the clarification of the issues involved in botulinum neurotoxin nomenclature. This publication presents a historical overview of the issues and provides guidelines for botulinum neurotoxin subtype nomenclature in the future.
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Affiliation(s)
| | - Theresa J Smith
- Molecular and Translational Sciences Division, United States Army Medical Institute of Infectious Diseases, Fort Detrick, MD 21702, USA.
| | - Fabrizio Anniballi
- National Reference Centre for Botulism, Istituto Superiore di Sanita, Rome 299-00161, Italy.
| | - John W Austin
- Bureau of Microbial Hazards, Health Canada, Ottawa, ON K1A 0K9, Canada.
| | - Luca Bano
- Istituto Zooprofilattico Sperimentale delle Venezie, Treviso 31020, Italy.
| | - Marite Bradshaw
- Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA.
| | - Paula Cuervo
- Área de Microbiología, Departamento de Patología, Universidad Nacional de Cuyo, Mendoza 450001, Argentina.
| | - Luisa W Cheng
- Foodborne Toxin Detection and Prevention Research Unit, Western Regional Research Center, U.S. Department of Agriculture, Albany, CA 94710, USA.
| | - Yagmur Derman
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki 00014, Finland.
| | | | - Audrey Fisher
- Applied Physics Laboratory, Johns Hopkins University, Baltimore, MD 21218, USA.
| | - Karen K Hill
- Los Alamos National Laboratories, Los Alamos, NM 87545, USA.
| | - Suzanne R Kalb
- National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA.
| | - Hannu Korkeala
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki 00014, Finland.
| | - Miia Lindström
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki 00014, Finland.
| | - Florigio Lista
- Army Medical and Veterinary Research Center, Rome 00184, Italy.
| | - Carolina Lúquez
- National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA.
| | - Christelle Mazuet
- Institut Pasteur, Bactéries anaérobies et Toxines, Paris 75015, France.
| | - Marco Pirazzini
- Biomedical Sciences Department, University of Padova, Padova 35131, Italy.
| | - Michel R Popoff
- Institut Pasteur, Bactéries anaérobies et Toxines, Paris 75015, France.
| | - Ornella Rossetto
- Biomedical Sciences Department, University of Padova, Padova 35131, Italy.
| | - Andreas Rummel
- Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover 30623, Germany.
| | - Dorothea Sesardic
- National Institute for Biological Standards and Control, a Centre of Medicines and Healthcare Products Regulatory Agency, Hertfordshire EN6 3QG, UK.
| | - Bal Ram Singh
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA.
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