1
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Hoyt KM, Barr JR, Hopkins AO, Dykes JK, Lúquez C, Kalb SR. Validation of a clinical assay for botulinum neurotoxins through mass spectrometric detection. J Clin Microbiol 2024; 62:e0162923. [PMID: 38687021 PMCID: PMC11237762 DOI: 10.1128/jcm.01629-23] [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: 12/04/2023] [Accepted: 04/02/2024] [Indexed: 05/02/2024] Open
Abstract
Botulism is a paralytic disease due to the inhibition of acetylcholine exocytosis at the neuromuscular junction, which can be lethal if left untreated. Botulinum neurotoxins (BoNTs) are produced by some spore-forming Clostridium bacteria. The current confirmatory assay to test for BoNTs in clinical specimens is the gold-standard mouse bioassay. However, an Endopep-MS assay method has been developed to detect BoNTs in clinical samples using benchtop mass spectrometric detection. This work demonstrates the validation of the Endopep-MS method for clinical specimens with the intent of method distribution in public health laboratories. The Endopep-MS assay was validated by assessing the sensitivity, robustness, selectivity, specificity, and reproducibility. The limit of detection was found to be equivalent to or more sensitive than the mouse bioassay. Specificity studies determined no cross-reactivity between the different serotypes and no false positives from an exclusivity panel of culture supernatants of enteric disease organisms and non-toxigenic strains of Clostridium. Inter-serotype specificity testing with 19 BoNT subtypes was 100% concordant with the expected results, accurately determining the presence of the correct serotype and the absence of incorrect serotypes. Additionally, a panel of potential interfering substances was used to test selectivity. Finally, clinical studies included clinical specimen stability and reproducibility, which was found to be 99.9% from a multicenter evaluation study. The multicenter validation study also included a clinical validation study, which yielded a 99.4% correct determination rate. Use of the Endopep-MS method will improve the capacity and response time for laboratory confirmation of botulism in public health laboratories.
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Affiliation(s)
- Kaitlin M. Hoyt
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - John R. Barr
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - André O. Hopkins
- Division of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Janet K. Dykes
- Division of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Carolina Lúquez
- Division of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Suzanne R. Kalb
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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2
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Ibrahim H, Retailleau K, Hornby F, Maignel J, Beard M, Daly DM. A Novel Catalytically Inactive Construct of Botulinum Neurotoxin A (BoNT/A) Directly Inhibits Visceral Sensory Signalling. Toxins (Basel) 2024; 16:30. [PMID: 38251246 PMCID: PMC10820156 DOI: 10.3390/toxins16010030] [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: 12/01/2023] [Revised: 12/30/2023] [Accepted: 01/03/2024] [Indexed: 01/23/2024] Open
Abstract
Botulinum neurotoxin A (BoNT/A) is a potent neurotoxin that silences cholinergic neurotransmission through the cleavage of the synaptic protein SNAP-25. Previous studies have shown that, in addition to its paralytic effects, BoNT/A can inhibit sensory nerve activity. The aim of this study was to identify how BoNT/A inhibits afferent signalling from the bladder. To investigate the role of SNAP-25 cleavage in the previously reported BoNT/A-dependent inhibition of sensory signalling, we developed a recombinant form of BoNT/A with an inactive light chain, rBoNT/A (0), unable to paralyse muscle. We also developed recombinant light chain (LC)-domain-only proteins to better understand the entry mechanisms, as the heavy chain (HC) of the protein is responsible for the internalisation of the light chain. We found that, despite a lack of catalytic activity, rBoNT/A (0) potently inhibited the afferent responses to bladder distension to a greater degree than catalytically active rBoNT/A. This was also clear from the testing of the LC-only proteins, as the inactive rLC/A (0) protein inhibited afferent responses significantly more than the active rLC/A protein. Immunohistochemistry for cleaved SNAP-25 was negative, and purinergic and nitrergic antagonists partially and totally reversed the sensory inhibition, respectively. These data suggest that the BoNT/A inhibition of sensory nerve activity in this assay is not due to the classical well-characterised 'double-receptor' mechanism of BoNT/A, is independent of SNAP25 cleavage and involves nitrergic and purinergic signalling mechanisms.
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Affiliation(s)
- Hodan Ibrahim
- School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston Campus, Preston PR1 2HE, UK
- Ipsen, Abingdon OX14 4RY, UK; (F.H.); (M.B.)
| | | | | | | | | | - Donna Marie Daly
- School of Pharmacy and Biomedical Sciences, University of Central Lancashire, Preston Campus, Preston PR1 2HE, UK
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Gregory KS, Hall PR, Onuh JP, Mojanaga OO, Liu SM, Acharya KR. Crystal Structure of the Catalytic Domain of a Botulinum Neurotoxin Homologue from Enterococcus faecium: Potential Insights into Substrate Recognition. Int J Mol Sci 2023; 24:12721. [PMID: 37628902 PMCID: PMC10454453 DOI: 10.3390/ijms241612721] [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: 06/28/2023] [Revised: 07/25/2023] [Accepted: 08/10/2023] [Indexed: 08/27/2023] Open
Abstract
Clostridium botulinum neurotoxins (BoNTs) are the most potent toxins known, causing the deadly disease botulism. They function through Zn2+-dependent endopeptidase cleavage of SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins, preventing vesicular fusion and subsequent neurotransmitter release from motor neurons. Several serotypes of BoNTs produced by Clostridium botulinum (BoNT/A-/G and/X) have been well-characterised over the years. However, a BoNT-like gene (homologue of BoNT) was recently identified in the non-clostridial species, Enterococcus faecium, which is the leading cause of hospital-acquired multi-drug resistant infections. Here, we report the crystal structure of the catalytic domain of a BoNT homologue from Enterococcus faecium (LC/En) at 2.0 Å resolution. Detailed structural analysis in comparison with the full-length BoNT/En AlphaFold2-predicted structure, LC/A (from BoNT/A), and LC/F (from BoNT/F) revealed putative subsites and exosites (including loops 1-5) involved in recognition of LC/En substrates. LC/En also appears to possess a conserved autoproteolytic cleavage site whose function is yet to be established.
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Affiliation(s)
- Kyle S. Gregory
- Department of Life Sciences, University of Bath, Claverton Down, Bath BA2 7AY, UK; (K.S.G.); (P.-R.H.); (J.P.O.); (O.O.M.)
| | - Peter-Rory Hall
- Department of Life Sciences, University of Bath, Claverton Down, Bath BA2 7AY, UK; (K.S.G.); (P.-R.H.); (J.P.O.); (O.O.M.)
| | - Jude Prince Onuh
- Department of Life Sciences, University of Bath, Claverton Down, Bath BA2 7AY, UK; (K.S.G.); (P.-R.H.); (J.P.O.); (O.O.M.)
| | - Otsile O. Mojanaga
- Department of Life Sciences, University of Bath, Claverton Down, Bath BA2 7AY, UK; (K.S.G.); (P.-R.H.); (J.P.O.); (O.O.M.)
| | - Sai Man Liu
- Protein Sciences Department, Ipsen Bioinnovation Limited, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK;
| | - K. Ravi Acharya
- Department of Life Sciences, University of Bath, Claverton Down, Bath BA2 7AY, UK; (K.S.G.); (P.-R.H.); (J.P.O.); (O.O.M.)
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4
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Liu Q, Gao Y, Cong H, Liao L. Ultrasound-assisted intravesical botulinum toxin A delivery attenuates acetic acid-induced bladder hyperactivity in rats. Front Pharmacol 2023; 14:1214145. [PMID: 37554988 PMCID: PMC10406439 DOI: 10.3389/fphar.2023.1214145] [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: 04/29/2023] [Accepted: 07/07/2023] [Indexed: 08/10/2023] Open
Abstract
Background: Intradetrusor injection of botulinum toxin A (BTX-A) is an effective treatment for overactive bladder (OAB). However, the occurrence of adverse events associated with BTX-A injection therapy hinders its acceptance among patients and its clinical promotion. Intravesical instillation of BTX-A offers a promising alternative to injection therapy for treating OAB. Nevertheless, due to the presence of the bladder permeability barrier (BPB) and the high molecular weight of BTX-A, direct instillation is unable to penetrate the bladder urothelium. Purpose: This study aims to investigate the safety and feasibility of ultrasound-assisted intravesical delivery of BTX-A and its potential benefits in a rat model of bladder hyperactivity induced by acetic acid instillation. Methods: Hengli BTX-A and microbubbles (MB) were mixed and prepared as a novel complex. The size distribution and zeta potentials of the complex were measured. On day 1, rats' bladders were instilled with 1 mL of saline, BTX-A (20 U in 1 mL), MB, or MB-BTX-A (20 U in 1 mL) complex with or without ultrasound (US) exposure (1 MHz, 1.5 W/cm2, 50% duty cycle, sonication for 10 s with a 10-s pause for a total of 10 min). The instillations were maintained for 30 min. After 7 days, cystometry was performed by filling the bladder with saline and 0.3% acetic acid (AA). Bladders were collected, weighed, and processed for immunoblotting, enzyme-linked immunosorbent assay (ELISA), histologic, and immunofluorescence analyses. Expression and distribution of SNAP-25 and SNAP-23 were assessed using Western blot and immunofluorescence. Calcitonin gene-related peptide (CGRP) in the bladder was detected using ELISA. Results: Intercontraction intervals (ICI) decreased by 72.99%, 76.16%, and 73.96% in rats pretreated with saline, BTX-A, and US + MB, respectively. However, rats treated with US + MB + BTX-A showed a significantly reduced response to AA instillation (57.31% decrease in ICI) without affecting amplitude, baseline pressure, or threshold pressure. Rats treated with US + MB + BTX-A exhibited increased cleavage of SNAP-25 and CGRP expression compared to the control group. Conclusion: Ultrasound-assisted intravesical delivery of BTX-A, with the assistance of MB cavitation, led to cleavage of SNAP-25, inhibition of calcitonin gene-related peptide release from afferent nerve terminals, and amelioration of acetic acid-induced bladder hyperactivity. These results support ultrasound-assisted intravesical delivery as an efficient non-injection method for administering BTX-A.
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Affiliation(s)
- Qinggang Liu
- Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
- Department of Urology, China Rehabilitation Research Center, Beijing, China
- School of Health and Life Sciences, University of Health and Rehabilitation Sciences, Qingdao, Shandong, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
| | - Yi Gao
- Department of Urology, China Rehabilitation Research Center, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
| | - Huiling Cong
- Department of Urology, China Rehabilitation Research Center, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
| | - Limin Liao
- Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
- Department of Urology, China Rehabilitation Research Center, Beijing, China
- School of Health and Life Sciences, University of Health and Rehabilitation Sciences, Qingdao, Shandong, China
- China Rehabilitation Science Institute, Beijing, China
- Beijing Key Laboratory of Neural Injury and Rehabilitation, Beijing, China
- School of Rehabilitation, Capital Medical University, Beijing, China
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Abstract
Investigation of fungal biology has been frequently motivated by the fact that many fungal species are important plant and animal pathogens. Such efforts have contributed significantly toward our understanding of fungal pathogenic lifestyles (virulence factors and strategies) and the interplay with host immune systems. In parallel, work on fungal allorecognition systems leading to the characterization of fungal regulated cell death determinants and pathways, has been instrumental for the emergent concept of fungal immunity. The uncovered evolutionary trans-kingdom parallels between fungal regulated cell death pathways and innate immune systems incite us to reflect further on the concept of a fungal immune system. Here, I briefly review key findings that have shaped the fungal immunity paradigm, providing a perspective on what I consider its most glaring knowledge gaps. Undertaking to fill such gaps would establish firmly the fungal immune system inside the broader field of comparative immunology.
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Affiliation(s)
- Asen Daskalov
- State Key Laboratory for Managing Biotic and Chemical Treats to the Quality and Safety of Agro-products, Institute of Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
- ImmunoConcEpT, CNRS UMR 5164, University of Bordeaux, Bordeaux, France
- Corresponding author
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6
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Ueda H. Non-Vesicular Release of Alarmin Prothymosin α Complex Associated with Annexin-2 Flop-Out. Cells 2023; 12:1569. [PMID: 37371039 DOI: 10.3390/cells12121569] [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: 05/09/2023] [Accepted: 06/05/2023] [Indexed: 06/29/2023] Open
Abstract
Nuclear protein prothymosin α (ProTα) is a unique member of damage-associated molecular patterns (DAMPs)/alarmins. ProTα prevents neuronal necrosis by causing a cell death mode switch in serum-starving or ischemic/reperfusion models in vitro and in vivo. Underlying receptor mechanisms include Toll-like receptor 4 (TLR4) and Gi-coupled receptor. Recent studies have revealed that the mode of the fatal stress-induced extracellular release of nuclear ProTα from cortical neurons in primary cultures, astrocytes and C6 glioma cells has two steps: ATP loss-induced nuclear release and the Ca2+-mediated formation of a multiple protein complex and its extracellular release. Under the serum-starving condition, ProTα is diffused from the nucleus throughout the cell due to the ATP loss-induced impairment of importin α-mediated nuclear transport. Subsequent mechanisms are all Ca2+-dependent. They include the formation of a protein complex with ProTα, S100A13, p40 Syt-1 and Annexin A2 (ANXA2); the fusion of the protein complex to the plasma membrane via p40 Syt-1-Stx-1 interaction; and TMEM16F scramblase-mediated ANXA2 flop-out. Subsequently, the protein complex is extracellularly released, leaving ANXA2 on the outer cell surface. The ANXA2 is then flipped in by a force of ATP8A2 activity, and the non-vesicular release of protein complex is repeated. Thus, the ANXA2 flop-out could play key roles in a new type of non-vesicular and non-classical release for DAMPs/alarmins, which is distinct from the modes conducted via gasdermin D or mixed-lineage kinase domain-like pseudokinase pores.
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Affiliation(s)
- Hiroshi Ueda
- Department and Institute of Pharmacology, National Defense Medical Center, Nei-hu, Taipei 114201, Taiwan
- Department of Pharmacology and Therapeutic Innovation, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8521, Japan
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7
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Fang Y, Chang AY, Verma D, Miyashita SI, Eszterhas S, Lee PG, Shen Y, Davis LR, Dong M, Bailey-Kellogg C, Griswold KE. Functional Deimmunization of Botulinum Neurotoxin Protease Domain via Computationally Driven Library Design and Ultrahigh-Throughput Screening. ACS Synth Biol 2023; 12:153-163. [PMID: 36623275 PMCID: PMC9872818 DOI: 10.1021/acssynbio.2c00426] [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: 08/05/2022] [Indexed: 01/11/2023]
Abstract
Botulinum neurotoxin serotype A (BoNT/A) is a widely used cosmetic agent that also has diverse therapeutic applications; however, adverse antidrug immune responses and associated loss of efficacy have been reported in clinical uses. Here, we describe computational design and ultrahigh-throughput screening of a massive BoNT/A light-chain (BoNT/A-LC) library optimized for reduced T cell epitope content and thereby dampened immunogenicity. We developed a functional assay based on bacterial co-expression of BoNT/A-LC library members with a Förster resonance energy transfer (FRET) sensor for BoNT/A-LC enzymatic activity, and we employed high-speed fluorescence-activated cell sorting (FACS) to identify numerous computationally designed variants having wild-type-like enzyme kinetics. Many of these variants exhibited decreased immunogenicity in humanized HLA transgenic mice and manifested in vivo paralytic activity when incorporated into full-length toxin. One variant achieved near-wild-type paralytic potency and a 300% reduction in antidrug antibody response in vivo. Thus, we have achieved a striking level of BoNT/A-LC functional deimmunization by combining computational library design and ultrahigh-throughput screening. This strategy holds promise for deimmunizing other biologics with complex superstructures and mechanisms of action.
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Affiliation(s)
- Yongliang Fang
- Thayer
School of Engineering, Dartmouth, Hanover, New Hampshire 03755, United States
- Department
of Urology, Boston Children’s Hospital, Boston, Massachusetts 02115, United States
- Department
of Microbiology and Department of Surgery, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Andrew Y. Chang
- Thayer
School of Engineering, Dartmouth, Hanover, New Hampshire 03755, United States
| | - Deeptak Verma
- Department
of Computer Science, Dartmouth, Hanover, New Hampshire 03755, United States
| | - Shin-Ichiro Miyashita
- Department
of Urology, Boston Children’s Hospital, Boston, Massachusetts 02115, United States
- Department
of Microbiology and Department of Surgery, Harvard Medical School, Boston, Massachusetts 02115, United States
- Department
of Food, Aroma and Cosmetic Chemistry, Tokyo
University of Agriculture, 196 Yasaka, Abashiri 099-2493, Japan
| | - Susan Eszterhas
- Thayer
School of Engineering, Dartmouth, Hanover, New Hampshire 03755, United States
| | - Pyung-Gang Lee
- Department
of Urology, Boston Children’s Hospital, Boston, Massachusetts 02115, United States
- Department
of Microbiology and Department of Surgery, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Yi Shen
- Department
of Urology, Boston Children’s Hospital, Boston, Massachusetts 02115, United States
- Department
of Microbiology and Department of Surgery, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Lydia R. Davis
- Thayer
School of Engineering, Dartmouth, Hanover, New Hampshire 03755, United States
| | - Min Dong
- Department
of Urology, Boston Children’s Hospital, Boston, Massachusetts 02115, United States
- Department
of Microbiology and Department of Surgery, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Chris Bailey-Kellogg
- Department
of Computer Science, Dartmouth, Hanover, New Hampshire 03755, United States
| | - Karl E. Griswold
- Thayer
School of Engineering, Dartmouth, Hanover, New Hampshire 03755, United States
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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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Rupp DC, Canty D, Rhéaume C, Sondergaard B, Niño C, Broide RS, Brideau-Andersen AD. A Preclinical Study Comparing the Activity and Potency of OnabotulinumtoxinA and PrabotulinumtoxinA. Clin Cosmet Investig Dermatol 2023; 16:581-591. [PMID: 36923693 PMCID: PMC10008670 DOI: 10.2147/ccid.s397999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 02/27/2023] [Indexed: 03/18/2023]
Abstract
Objective The goal of this study was to compare the unit-to-unit biological activity of the vacuum-dried formulation of prabotulinumtoxinA (prabotA) and onabotulinumtoxinA (onabotA) in preclinical assays. Methods Reconstituted 100 U vials of prabotA and onabotA were tested in 3 distinct assays: plate-capture light chain activity (PC-LCA), measuringlight chain enzymatic activity after recovery of toxin from reconstituted product using a proprietary toxin capture step; cell-based potency assay (CBPA), measuring the intoxication steps of binding, translocation, and light chain activity (synaptosomal-associated protein 25 [SNAP25] cleavage); and mouse Digit Abduction Score (DAS), evaluating muscle paresis. Each assay tested 3 separate prabotA and onabotA lots on several independent test dates. Results Multiple orthogonal assays established that when assessed on a unit-to-unit basis, the biological activity of prabotA is lower than that of onabotA. In the PC-LCA and CBPA assays, onabotA displayed 1.51 ± 0.14-fold higher (mean ± SD) and 1.33 ± 0.07-fold higher (mean of pooled lots ± SEM) activity than prabotA, respectively. Similarly, the mouse DAS data showed that onabotA had 1.4 ± 0.1-fold higher (mean ± SEM) potency than prabotA. Results of all 3 assays demonstrated differences in potency, efficacy, and duration of action between onabotA and prabotA on a unit-to-unit basis. Conclusion Preclinical assays established differences in the biological activity of onabotA and prabotA, supporting that the units of biological activity are not interchangeable.
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Affiliation(s)
- David C Rupp
- Allergan Aesthetics, an AbbVie Company, Irvine, CA, USA
| | - David Canty
- Allergan Aesthetics, an AbbVie Company, Irvine, CA, USA
| | | | | | - Celina Niño
- Allergan Aesthetics, an AbbVie Company, Irvine, CA, USA
| | - Ron S Broide
- Allergan Aesthetics, an AbbVie Company, Irvine, CA, USA
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BoNT/A in the Urinary Bladder-More to the Story than Silencing of Cholinergic Nerves. Toxins (Basel) 2022; 14:toxins14010053. [PMID: 35051030 PMCID: PMC8780360 DOI: 10.3390/toxins14010053] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 12/23/2021] [Accepted: 12/27/2021] [Indexed: 02/06/2023] Open
Abstract
Botulinum neurotoxin (BoNT/A) is an FDA and NICE approved second-line treatment for overactive bladder (OAB) in patients either not responsive or intolerant to anti-cholinergic drugs. BoNT/A acts to weaken muscle contraction by blocking release of the neurotransmitter acetyl choline (ACh) at neuromuscular junctions. However, this biological activity does not easily explain all the observed effects in clinical and non-clinical studies. There are also conflicting reports of expression of the BoNT/A protein receptor, SV2, and intracellular target protein, SNAP-25, in the urothelium and bladder. This review presents the current evidence of BoNT/A’s effect on bladder sensation, potential mechanisms by which it might exert these effects and discusses recent advances in understanding the action of BoNT in bladder tissue.
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11
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Vaidyanathan VV, Binz T. Ability of human SNAP-23 to generate high molecular weight SDS-resistant ternary SNARE complexes is influenced by C-terminal coil content. Biochem Biophys Rep 2021; 28:101150. [PMID: 34703905 PMCID: PMC8524102 DOI: 10.1016/j.bbrep.2021.101150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 08/23/2021] [Accepted: 09/21/2021] [Indexed: 11/26/2022] Open
Abstract
Using in vitro protein complex formation assay, ability of SNAP-25 isoforms to generate SDS-resistant ternary SNARE complexes with Syntaxin-1 and VAMP-2 was investigated. Major SNAP-25 family proteins were found to generate heat-resistant ternary complexes with varying efficiency. Compared to human SNAP-25, its non-neuronal counterparts SNAP-23 and SNAP-29 formed lower amounts of ternary complexes. Changing Pro182 in human SNAP-23 to Arg182 (SNAP-23 P182R) improved its ability to bind partners and form complexes. In silico analysis of C-terminal helical content in various SNAP-25 family members showed that except human SNAP-23, all others displayed secondary α-helical conformation. We also report that human SNAP-29 is resistant to the proteolytic action of botulinum neurotoxin A even when applied at large concentration. Human SNAP-23 forms reduced amounts of ternary SNARE complexes than human SNAP-25. SNAP-25 family proteins show varying levels of secondary structure at the C-terminus. C-terminal coil content influences neurotoxin sensitivity and ability to form stable ternary SNARE complexes.
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Affiliation(s)
| | - Thomas Binz
- Institute of Cellular Biochemistry, Hannover Medical School, Hannover, 30625, Germany
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12
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Turner LD, Nielsen AL, Lin L, Pellett S, Sugane T, Olson ME, Johnson EA, Janda KD. Irreversible inhibition of BoNT/A protease: proximity-driven reactivity contingent upon a bifunctional approach. RSC Med Chem 2021; 12:960-969. [PMID: 34223161 PMCID: PMC8221255 DOI: 10.1039/d1md00089f] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/03/2021] [Indexed: 12/27/2022] Open
Abstract
Botulinum neurotoxin A (BoNT/A) is categorized as a Tier 1 bioterrorism agent and persists within muscle neurons for months, causing paralysis. A readily available treatment that abrogates BoNT/A's toxicity and longevity is a necessity in the event of a widespread BoNT/A attack and for clinical treatment of botulism, yet remains an unmet need. Herein, we describe a comprehensive warhead screening campaign of bifunctional hydroxamate-based inhibitors for the irreversible inhibition of the BoNT/A light chain (LC). Using the 2,4-dichlorocinnamic hydroxamic acid (DCHA) metal-binding pharmacophore modified with a pendent warhead, a total of 37 compounds, possessing 13 distinct warhead types, were synthesized and evaluated for time-dependent inhibition against the BoNT/A LC. Iodoacetamides, maleimides, and an epoxide were found to exhibit time-dependent inhibition and their k GSH measured as a description of reactivity. The epoxide exhibited superior time-dependent inhibition over the iodoacetamides, despite reacting with glutathione (GSH) 51-fold slower. The proximity-driven covalent bond achieved with the epoxide inhibitor was contingent upon the vital hydroxamate-Zn2+ anchor in placing the warhead in an optimal position for reaction with Cys165. Monofunctional control compounds exemplified the necessity of the bifunctional approach, and Cys165 modification was confirmed through high-resolution mass spectrometry (HRMS) and ablation of time-dependent inhibitory activity against a C165A variant. Compounds were also evaluated against BoNT/A-intoxicated motor neuron cells, and their cell toxicity, serum stability, and selectivity against matrix metalloproteinases (MMPs) were characterized. The bifunctional approach allows the use of less intrinsically reactive electrophiles to intercept Cys165, thus expanding the toolbox of potential warheads for selective irreversible BoNT/A LC inhibition. We envision that this dual-targeted strategy is amenable to other metalloproteases that also possess non-catalytic cysteines proximal to the active-site metal center.
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Affiliation(s)
- Lewis D Turner
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), Scripps Research 10550 N Torrey Pines Road La Jolla CA 92037 USA
| | - Alexander L Nielsen
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), Scripps Research 10550 N Torrey Pines Road La Jolla CA 92037 USA
- Center for Biopharmaceuticals & Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen Universitetsparken 2 DK-2100 Copenhagen Denmark
| | - Lucy Lin
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), Scripps Research 10550 N Torrey Pines Road La Jolla CA 92037 USA
| | - Sabine Pellett
- Department of Bacteriology, University of Wisconsin 1550 Linden Drive Madison WI 53706 USA
| | - Takashi Sugane
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), Scripps Research 10550 N Torrey Pines Road La Jolla CA 92037 USA
| | - Margaret E Olson
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), Scripps Research 10550 N Torrey Pines Road La Jolla CA 92037 USA
- College of Pharmacy, Roosevelt University Schaumburg IL 60173 USA
| | - Eric A Johnson
- Department of Bacteriology, University of Wisconsin 1550 Linden Drive Madison WI 53706 USA
| | - Kim D Janda
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), Scripps Research 10550 N Torrey Pines Road La Jolla CA 92037 USA
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13
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C20orf204, a hepatocellular carcinoma-specific protein interacts with nucleolin and promotes cell proliferation. Oncogenesis 2021; 10:31. [PMID: 33731669 PMCID: PMC7969625 DOI: 10.1038/s41389-021-00320-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 02/23/2021] [Accepted: 02/26/2021] [Indexed: 11/16/2022] Open
Abstract
In most human cancers, a large number of proteins with driver mutations are involved in tumor development, implying that multiple fine tuners are involved in cancer formation and/or maintenance. A useful strategy for cancer therapy may therefore be to target multiple cancer type-specific fine tuners. Furthermore, genome-wide association studies of tumor samples have identified a large number of long noncoding (lnc)RNA associated with various types of tumor. In this context we have previously found that C20orf204 (a splice variant of Linc00176) RNA contains a 189 amino acid (AA) long open reading frame (C20orf204-189AA) that is expressed predominantly in hepatocellular carcinoma (HCC). We report here that a protein, C20orf204-189AA, was detected in the nucleus of 14 out of 20 primary HCC, but not in control livers. Strikingly, overexpression of C20orf204-189AA enhanced cell proliferation and ribosomal RNA transcription. C20orf204-189AA is co-localized, and interacted with nucleolin via the C-terminal and with ribosomal RNA via the N-terminal domain. Furthermore, the expression of C20orf204-189AA upregulates the protein level of nucleolin. Nucleolin and C20orf204 mRNA levels in HCC are correlated with tumor differentiation grade and patient survival, suggesting that C20orf204-189AA is a cancer type-specific fine tuner in some HCC that presents itself for potential targeting therapy and cancer biomarker. Thus, cancer cells exhibit remarkable transcriptome alterations partly by adopting cancer-specific splicing isoforms of noncoding RNAs and may participate in tumor development.
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14
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Mehlmann LM, Uliasz TF, Lowther KM. SNAP23 is required for constitutive and regulated exocytosis in mouse oocytes†. Biol Reprod 2020; 101:338-346. [PMID: 31201423 DOI: 10.1093/biolre/ioz106] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 04/17/2019] [Accepted: 06/10/2019] [Indexed: 12/25/2022] Open
Abstract
Mammalian oocytes are stored in the ovary for prolonged periods, and arrested in meiotic prophase. During this period, their plasma membranes are constantly being recycled by endocytosis and exocytosis. However, the function of this membrane turnover is unknown. Here, we investigated the requirement for exocytosis in the maintenance of meiotic arrest. Using Trim-away, a newly developed method for rapidly and specifically depleting proteins in oocytes, we have identified the SNARE protein, SNAP23, to be required for meiotic arrest. Degradation of SNAP23 causes premature meiotic resumption in follicle-enclosed oocytes. The reduction in SNAP23 is associated with loss of gap junction communication between the oocyte and surrounding follicle cells. Reduction of SNAP23 protein also inhibits regulated exocytosis in response to a Ca2+ stimulus (cortical granule exocytosis), as measured by lectin staining and cleavage of ZP2. Our results show an essential role for SNAP23 in two key processes that occur in mouse oocytes and eggs.
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Affiliation(s)
- Lisa M Mehlmann
- Department of Cell Biology, UConn Health, Farmington, Connecticut, USA
| | - Tracy F Uliasz
- Department of Cell Biology, UConn Health, Farmington, Connecticut, USA
| | - Katie M Lowther
- Department of Cell Biology, UConn Health, Farmington, Connecticut, USA
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15
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Involvement of SNARE Protein Interaction for Non-classical Release of DAMPs/Alarmins Proteins, Prothymosin Alpha and S100A13. Cell Mol Neurobiol 2020; 41:1817-1828. [PMID: 32856232 DOI: 10.1007/s10571-020-00950-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 08/19/2020] [Indexed: 12/30/2022]
Abstract
Prothymosin alpha (ProTα) is involved in multiple cellular processes. Upon serum-free stress, ProTα lacking a signal peptide sequence is non-classically released from C6 glioma cells as a complex with Ca2+-binding cargo protein S100A13. Thus, ProTα and S100A13 are conceived to be members of damage-associated molecular patterns (DAMPs)/alarmins. However, it remains to be determined whether stress-induced release of ProTα and S100A13 involves SNARE proteins in the mechanisms underlying membrane tethering of the multiprotein complex. In the present study, we used C6 glioma cells as a model of ProTα release. In pull-down assay, p40 synaptotagmin-1 (Syt-1), a vesicular SNARE, formed a hetero-oligomeric complex with homodimeric S100A13 in a Ca2+-dependent manner. The interaction between p40 Syt-1 and S100A13 was also Ca2+-dependent in surface plasmon resonance (SPR). Immunoprecipitation using conditioned medium (CM) revealed that p40 Syt-1 was co-released with ProTα and S100A13 upon serum-free stress. In in situ proximity ligation assay (PLA), Syt-1 interacted with S100A13 upon serum-free stress in C6 glioma cells. The intracellular delivery of anti-Syt-1 IgG blocked serum free-induced release of ProTα and S100A13. Serum free-induced ProTα-EGFP release was significantly blocked by botulinum neurotoxin/C1 (BoNT/C1), which cleaves target SNARE syntaxin-1 (Stx-1). In immunocytochemistry, the cellular loss of ProTα-EGFP, S100A13, and Syt-1 was also blocked by BoNT/C1. Furthermore, the intracellular delivery of anti-Stx-1 IgG or Stx-1 siRNA treatment blocked Syt-1, S100A13 and ProTα release from C6 glioma cells. All these findings suggest that SNARE proteins play roles in stress-induced non-classical release of DAMPs/alarmins proteins, ProTα and S100A13 from C6 glioma cells.
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16
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Mechanism of Action of Botulinum Toxin A in Treatment of Functional Urological Disorders. Toxins (Basel) 2020; 12:toxins12020129. [PMID: 32085522 PMCID: PMC7077222 DOI: 10.3390/toxins12020129] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 02/03/2020] [Accepted: 02/14/2020] [Indexed: 12/03/2022] Open
Abstract
Intravesical botulinum toxin (BoNT) injection is effective in reducing urgency and urinary incontinence. It temporarily inhibits the detrusor muscle contraction by blocking the release of acetylcholine (Ach) from the preganglionic and postganglionic nerves in the efferent nerves. BoNT-A also blocks ATP release from purinergic efferent nerves in the detrusor muscle. In afferent nerves, BoNT-A injection markedly reduces the urothelial ATP release and increases nitric oxide (NO) release from the urothelium. BoNT-A injection in the urethra or bladder has been developed in the past few decades as the treatment method for detrusor sphincter dyssyndergia, incontinence due to neurogenic or idiopathic detrusor overactivity, sensory disorders, including bladder hypersensitivity, overactive bladder, and interstitial cystitis/chronic pelvic pain syndrome. Although the FDA only approved BoNT-A injection treatment for neurogenic detrusor overactivity and for refractory overactive bladder, emerging clinical trials have demonstrated the benefits of BoNT-A treatment in functional urological disorders. Cautious selection of patients and urodynamic evaluation for confirmation of diagnosis are crucial to maximize the successful outcomes of BoNT-A treatment.
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17
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Che Y, Siprashvili Z, Kovalski JR, Jiang T, Wozniak G, Elcavage L, Khavari PA. KRAS regulation by small non-coding RNAs and SNARE proteins. Nat Commun 2019; 10:5118. [PMID: 31712554 PMCID: PMC6848142 DOI: 10.1038/s41467-019-13106-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 10/13/2019] [Indexed: 12/30/2022] Open
Abstract
KRAS receives and relays signals at the plasma membrane (PM) where it transmits extracellular growth factor signals to downstream effectors. SNORD50A/B were recently found to bind KRAS and inhibit its tumorigenic action by unknown mechanisms. KRAS proximity protein labeling was therefore undertaken in SNORD50A/B wild-type and knockout cells, revealing that SNORD50A/B RNAs shape the composition of proteins proximal to KRAS, notably by inhibiting KRAS proximity to the SNARE vesicular transport proteins SNAP23, SNAP29, and VAMP3. To remain enriched on the PM, KRAS undergoes cycles of endocytosis, solubilization, and vesicular transport to the PM. Here we report that SNAREs are essential for the final step of this process, with KRAS localization to the PM facilitated by SNAREs but antagonized by SNORD50A/B. Antagonism between SNORD50A/B RNAs and specific SNARE proteins thus controls KRAS localization, signaling, and tumorigenesis, and disrupting SNARE-enabled KRAS function represents a potential therapeutic opportunity in KRAS-driven cancer.
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Affiliation(s)
- Yonglu Che
- Program in Epithelial Biology, Stanford University, Stanford, CA, 94305, USA
- Program in Cancer Biology, Stanford University, Stanford, CA, 94305, USA
| | - Zurab Siprashvili
- Program in Epithelial Biology, Stanford University, Stanford, CA, 94305, USA
- Program in Cancer Biology, Stanford University, Stanford, CA, 94305, USA
| | - Joanna R Kovalski
- Program in Epithelial Biology, Stanford University, Stanford, CA, 94305, USA
- Program in Cancer Biology, Stanford University, Stanford, CA, 94305, USA
| | - Tiffany Jiang
- Program in Epithelial Biology, Stanford University, Stanford, CA, 94305, USA
| | - Glenn Wozniak
- Program in Epithelial Biology, Stanford University, Stanford, CA, 94305, USA
| | - Lara Elcavage
- Program in Epithelial Biology, Stanford University, Stanford, CA, 94305, USA
| | - Paul A Khavari
- Program in Epithelial Biology, Stanford University, Stanford, CA, 94305, USA.
- Program in Cancer Biology, Stanford University, Stanford, CA, 94305, USA.
- VA Palo Alto Healthcare System, Palo Alto, CA, 94304, USA.
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18
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Construction of functional chimeras of syntaxin-1A and its yeast orthologue, and their application to the yeast cell-based assay for botulinum neurotoxin serotype C. Biochim Biophys Acta Gen Subj 2019; 1863:129396. [PMID: 31302181 DOI: 10.1016/j.bbagen.2019.07.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 06/14/2019] [Accepted: 07/10/2019] [Indexed: 11/23/2022]
Abstract
BACKGROUND Botulinum neurotoxins (BoNTs) prevent synaptic transmission because they hydrolyze synaptic N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs). BoNT serotype C (BoNT/C) targets syntaxin-1A and SNAP-25, and is expected to be applied to cosmetic and therapeutic uses. SNAREs are evolutionally conserved proteins and in yeast a syntaxin-1A orthologue Sso1 is involved in exocytosis. The substrate specificity of BoNT/C is strict and it cannot cleave Sso1. METHODS Domain swapping and mutational screenings were performed to generate functional chimeras SNAREs of syntaxin-1A and Sso1. Such chimeras are expressed in yeast cells and assessed whether they are susceptible to BoNT/C digestion. RESULTS The Sso1 and syntaxin-1A chimera (Sso1/STX1A), in which the SNARE domain in Sso1 was replaced with that of syntaxin-1A, was not functional in yeast. The functional incompatibility of Sso1/STX1A was attributable to its accumulation in the ER. We found several mutations that could release Sso1/STX1A from the ER to make the chimera functional in yeast. Yeast cells harboring the mutant chimeras grew similarly to wild-type cells. However, unlike wild-type, yeast harboring the mutant chimeras exhibited a severe growth defect upon expression of BoNT/C. Results of further domain swapping analyses suggest that Sso1 is not digested by BoNT/C because it lacks a binding region to BoNT/C (α-exosite-binding region). CONCLUSIONS We obtained functional Sso1/STX1A chimeras, which can be applied to a yeast cell-based BoNT/C assay. BoNT/C can recognize these chimeras in a similar manner to syntaxin-1A. GENERAL SIGNIFICANCE The yeast cell-based BoNT/C assay would be useful to characterize and engineer BoNT/C.
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19
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Real-Time Monitoring of a Botulinum Neurotoxin Using All-Carbon Nanotube-Based Field-Effect Transistor Devices. SENSORS 2018; 18:s18124235. [PMID: 30513867 PMCID: PMC6308983 DOI: 10.3390/s18124235] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 11/23/2018] [Accepted: 11/27/2018] [Indexed: 02/01/2023]
Abstract
The possibility of exposure to botulinum neurotoxin (BoNT), a powerful and potential bioterrorism agent, is considered to be ever increasing. The current gold-standard assay, live-mouse lethality, exhibits high sensitivity but has limitations including long assay times, whereas other assays evince rapidity but lack factors such as real-time monitoring or portability. In this study, we aimed to devise a novel detection system that could detect BoNT at below-nanomolar concentrations in the form of a stretchable biosensor. We used a field-effect transistor with a p-type channel and electrodes, along with a channel comprising aligned carbon nanotube layers to detect the type E light chain of BoNT (BoNT/E-Lc). The detection of BoNT/E-Lc entailed observing the cleavage of a unique peptide and the specific bonding between BoNT/E-Lc and antibody BoNT/E-Lc (Anti-BoNT/E-Lc). The unique peptide was cleaved by 60 pM BoNT/E-Lc; notably, 52 fM BoNT/E-Lc was detected within 1 min in the device with the antibody in the bent state. These results demonstrated that an all-carbon nanotube-based device (all-CNT-based device) could be produced without a complicated fabrication process and could be used as a biosensor with high sensitivity, suggesting its potential development as a wearable BoNT biosensor.
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20
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Lam KH, Sikorra S, Weisemann J, Maatsch H, Perry K, Rummel A, Binz T, Jin R. Structural and biochemical characterization of the protease domain of the mosaic botulinum neurotoxin type HA. Pathog Dis 2018; 76:4982781. [PMID: 29688327 DOI: 10.1093/femspd/fty044] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 04/20/2018] [Indexed: 11/13/2022] Open
Abstract
The extreme toxicity of botulinum neurotoxins (BoNTs) relies on their specific cleavage of SNARE proteins, which eventually leads to muscle paralysis. One newly identified mosaic toxin, BoNT/HA (aka H or FA), cleaves VAMP-2 at a unique position between residues L54 and E55, but the molecular basis underlying VAMP-2 recognition of BoNT/HA remains poorly characterized. Here, we report a ∼2.09 Å resolution crystal structure of the light chain protease domain of BoNT/HA (LC/HA). Structural comparison between LC/HA and LC of BoNT/F1 (LC/F1) reveals distinctive hydrophobic and electrostatic features near the active sites, which may explain their different VAMP-2 cleavage sites. When compared to BoNT/F5 that cleaves VAMP-2 at the same site as BoNT/HA, LC/HA displays higher affinity for VAMP-2, which could be caused by their different surface charge properties surrounding a VAMP-2 exosite-binding cleft. Furthermore, systematic mutagenesis studies on VAMP-2 and structural modeling demonstrate that residues R47 to K59 spanning the cleavage site in VAMP-2 may adopt a novel extended conformation when interacting with LC/HA and LC/F5. Taken together, our structure provides new insights into substrate recognition of BoNT/HA and paves the way for rational design of small molecule or peptide inhibitors against LC/HA.
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Affiliation(s)
- Kwok-Ho Lam
- Department of Physiology and Biophysics, University of California, Irvine, CA 92697 USA
| | - Stefan Sikorra
- Institut für Zellbiochemie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
| | - Jasmin Weisemann
- Institut für Toxikologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
| | - Hannah Maatsch
- Institut für Zellbiochemie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
| | - Kay Perry
- NE-CAT and Department of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Andreas Rummel
- Institut für Toxikologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
| | - Thomas Binz
- Institut für Zellbiochemie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
| | - Rongsheng Jin
- Department of Physiology and Biophysics, University of California, Irvine, CA 92697 USA
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21
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Fonfria E, Elliott M, Beard M, Chaddock JA, Krupp J. Engineering Botulinum Toxins to Improve and Expand Targeting and SNARE Cleavage Activity. Toxins (Basel) 2018; 10:toxins10070278. [PMID: 29973505 PMCID: PMC6071219 DOI: 10.3390/toxins10070278] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 06/29/2018] [Accepted: 07/01/2018] [Indexed: 12/14/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are highly successful protein therapeutics. Over 40 naturally occurring BoNTs have been described thus far and, of those, only 2 are commercially available for clinical use. Different members of the BoNT family present different biological properties but share a similar multi-domain structure at the molecular level. In nature, BoNTs are encoded by DNA in producing clostridial bacteria and, as such, are amenable to recombinant production through insertion of the coding DNA into other bacterial species. This, in turn, creates possibilities for protein engineering. Here, we review the production of BoNTs by the natural host and also recombinant production approaches utilised in the field. Applications of recombinant BoNT-production include the generation of BoNT-derived domain fragments, the creation of novel BoNTs with improved performance and enhanced therapeutic potential, as well as the advancement of BoNT vaccines. In this article, we discuss site directed mutagenesis, used to affect the biological properties of BoNTs, including approaches to alter their binding to neurons and to alter the specificity and kinetics of substrate cleavage. We also discuss the target secretion inhibitor (TSI) platform, in which the neuronal binding domain of BoNTs is substituted with an alternative cellular ligand to re-target the toxins to non-neuronal systems. Understanding and harnessing the potential of the biological diversity of natural BoNTs, together with the ability to engineer novel mutations and further changes to the protein structure, will provide the basis for increasing the scope of future BoNT-based therapeutics.
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Affiliation(s)
- Elena Fonfria
- Ipsen Bioinnovation, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK.
| | - Mark Elliott
- Ipsen Bioinnovation, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK.
| | - Matthew Beard
- Ipsen Bioinnovation, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK.
| | - John A Chaddock
- Ipsen Bioinnovation, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK.
| | - Johannes Krupp
- Ipsen Innovation, 5 Avenue du Canada, 91940 Les Ulis, France.
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22
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Light Chain Diversity among the Botulinum Neurotoxins. Toxins (Basel) 2018; 10:toxins10070268. [PMID: 30004421 PMCID: PMC6070880 DOI: 10.3390/toxins10070268] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 06/19/2018] [Accepted: 06/21/2018] [Indexed: 12/30/2022] Open
Abstract
Botulinum neurotoxins (BoNT) are produced by several species of clostridium. There are seven immunologically unique BoNT serotypes (A⁻G). The Centers for Disease Control classifies BoNTs as 'Category A' select agents and are the most lethal protein toxins for humans. Recently, BoNT-like proteins have also been identified in several non-clostridia. BoNTs are di-chain proteins comprised of an N-terminal zinc metalloprotease Light Chain (LC) and a C-terminal Heavy Chain (HC) which includes the translocation and receptor binding domains. The two chains are held together by a disulfide bond. The LC cleaves Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs). The cleavage of SNAREs inhibits the fusion of synaptic vesicles to the cell membrane and the subsequent release of acetylcholine, which results in flaccid paralysis. The LC controls the catalytic properties and the duration of BoNT action. This review discusses the mechanism for LC catalysis, LC translocation, and the basis for the duration of LC action. Understanding these properties of the LC may expand the applications of BoNT as human therapies.
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23
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Mansfield MJ, Doxey AC. Genomic insights into the evolution and ecology of botulinum neurotoxins. Pathog Dis 2018; 76:4978416. [PMID: 29684130 DOI: 10.1093/femspd/fty040] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 04/17/2018] [Indexed: 11/14/2022] Open
Affiliation(s)
- Michael J Mansfield
- Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Andrew C Doxey
- Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
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Backhaus P, Langenhan T, Neuser K. Effects of transgenic expression of botulinum toxins in Drosophila. J Neurogenet 2017; 30:22-31. [PMID: 27276193 DOI: 10.3109/01677063.2016.1166223] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Clostridial neurotoxins (botulinum toxins and tetanus toxin) disrupt neurotransmitter release by cleaving neuronal SNARE proteins. We generated transgenic flies allowing for conditional expression of different botulinum toxins and evaluated their potential as tools for the analysis of synaptic and neuronal network function in Drosophila melanogaster by applying biochemical assays and behavioral analysis. On the biochemical level, cleavage assays in cultured Drosophila S2 cells were performed and the cleavage efficiency was assessed via western blot analysis. We found that each botulinum toxin cleaves its Drosophila SNARE substrate but with variable efficiency. To investigate the cleavage efficiency in vivo, we examined lethality, larval peristaltic movements and vision dependent motion behavior of adult Drosophila after tissue-specific conditional botulinum toxin expression. Our results show that botulinum toxin type B and botulinum toxin type C represent effective alternatives to established transgenic effectors, i.e. tetanus toxin, interfering with neuronal and non-neuronal cell function in Drosophila and constitute valuable tools for the analysis of synaptic and network function.
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Affiliation(s)
- Philipp Backhaus
- a Department of Neurophysiology , Institute of Physiology, University of Würzburg , Würzburg , Germany
| | - Tobias Langenhan
- a Department of Neurophysiology , Institute of Physiology, University of Würzburg , Würzburg , Germany
| | - Kirsa Neuser
- a Department of Neurophysiology , Institute of Physiology, University of Würzburg , Würzburg , Germany ;,b Carl-Ludwig-Institute for Physiology, Medical Faculty , University of Leipzig , Leipzig , Germany
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25
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Carle S, Pirazzini M, Rossetto O, Barth H, Montecucco C. High Conservation of Tetanus and Botulinum Neurotoxins Cleavage Sites on Human SNARE Proteins Suggests That These Pathogens Exerted Little or No Evolutionary Pressure on Humans. Toxins (Basel) 2017; 9:toxins9120404. [PMID: 29257047 PMCID: PMC5744124 DOI: 10.3390/toxins9120404] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 12/14/2017] [Accepted: 12/15/2017] [Indexed: 01/07/2023] Open
Abstract
The Genome Aggregation Database presently contains >120,000 human genomes. We searched in this database for the presence of mutations at the sites of tetanus (TeNT) and botulinum neurotoxins (BoNTs) cleavages of the three SNARE proteins: VAMP, SNAP-25 and Syntaxin. These mutations could account for some of the BoNT/A resistant patients. At the same time, this approach was aimed at testing the possibility that TeNT and BoNT may have acted as selective agents in the development of resistance to tetanus or botulism. We found that mutations of the SNARE proteins are very rare and concentrated outside the SNARE motif required for the formation of the SNARE complex involved in neuroexocytosis. No changes were found at the BoNT cleavage sites of VAMP and syntaxins and only one very rare mutation was found in the essential C-terminus region of SNAP-25, where Arg198 was replaced with a Cys residue. This is the P1’ cleavage site for BoNT/A and the P1 cleavage site for BoNT/C. We found that the Arg198Cys mutation renders SNAP-25 resistant to BoNT/A. Nonetheless, its low frequency (1.8 × 10−5) indicates that mutations of SNAP-25 at the BoNT/A cleavage site are unlikely to account for the existence of BoNT/A resistant patients. More in general, the present findings indicate that tetanus and botulinum neurotoxins have not acted as selective agents during human evolution as it appears to have been the case for tetanus in rats and chicken.
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Affiliation(s)
- Stefan Carle
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
| | - Marco Pirazzini
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy.
| | - Ornella Rossetto
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy.
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
| | - Cesare Montecucco
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/B, 35131 Padova, Italy.
- Institute for Neuroscience, National Research Council, Via Ugo Bassi 58/B, 35131 Padova, Italy.
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Michaeli L, Gottfried I, Bykhovskaia M, Ashery U. Phosphatidylinositol (4, 5)-bisphosphate targets double C2 domain protein B to the plasma membrane. Traffic 2017; 18:825-839. [PMID: 28941037 DOI: 10.1111/tra.12528] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 09/18/2017] [Accepted: 09/18/2017] [Indexed: 01/05/2023]
Abstract
Double C2 domain protein B (DOC2B) is a high-affinity Ca2+ sensor that translocates from the cytosol to the plasma membrane (PM) and promotes vesicle priming and fusion. However, the molecular mechanism underlying its translocation and targeting to the PM in living cells is not completely understood. DOC2B interacts in vitro with the PM components phosphatidylserine, phosphatidylinositol (4, 5)-bisphosphate [PI(4, 5)P2 ] and target SNAREs (t-SNAREs). Here, we show that PI(4, 5)P2 hydrolysis at the PM of living cells abolishes DOC2B translocation, whereas manipulations of t-SNAREs and other phosphoinositides have no effect. Moreover, we were able to redirect DOC2B to intracellular membranes by synthesizing PI(4, 5)P2 in those membranes. Molecular dynamics simulations and mutagenesis in the calcium and PI(4, 5)P2 -binding sites strengthened our findings, demonstrating that both calcium and PI(4, 5)P2 are required for the DOC2B-PM association and revealing multiple PI(4, 5)P2 -C2B interactions. In addition, we show that DOC2B translocation to the PM is ATP-independent and occurs in a diffusion-like manner. Our data suggest that the Ca2+ -triggered translocation of DOC2B is diffusion-driven and aimed at PI(4, 5)P2 -containing membranes.
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Affiliation(s)
- Lirin Michaeli
- Department of Neurobiology, Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, Israel
| | - Irit Gottfried
- Department of Neurobiology, Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, Israel
| | | | - Uri Ashery
- Department of Neurobiology, Faculty of Life Sciences, Tel-Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv, Israel
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Yadirgi G, Stickings P, Rajagopal S, Liu Y, Sesardic D. Immuno-detection of cleaved SNAP-25 from differentiated mouse embryonic stem cells provides a sensitive assay for determination of botulinum A toxin and antitoxin potency. J Immunol Methods 2017; 451:90-99. [PMID: 28943257 DOI: 10.1016/j.jim.2017.09.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 09/19/2017] [Accepted: 09/20/2017] [Indexed: 01/12/2023]
Abstract
Botulinum toxin type A is a causative agent of human botulism. Due to high toxicity and ease of production it is classified by the Centres for Disease Control and Prevention as a category A bioterrorism agent. The same serotype, BoNT/A, is also the most widely used in pharmaceutical preparations for treatment of a diverse range of neuromuscular disorders. Traditionally, animals are used to confirm the presence and activity of toxin and to establish neutralizing capabilities of countermeasures in toxin neutralization tests. Cell based assays for BoNT/A have been reported as the most viable alternative to animal models, since they are capable of reflecting all key steps (binding, translocation, internalization and cleavage of intracellular substrate) involved in toxin activity. In this paper we report preliminary development of a simple immunochemical method for specifically detecting BoNT/A cleaved intracellular substrate, SNAP-25, in cell lysates of neurons derived from mouse embryonic stem cells. The assay offers sensitivity of better than 0.1LD50/ml (3fM) which is not matched by other functional assays, including the mouse bioassay, and provides serotype specificity for quantitative detection of BoNT/A and anti-BoNT/A antitoxin. Subject to formal validation, the method described here could potentially be used as a substitute for the mouse bioassay to measure potency and consistency of therapeutic products.
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Affiliation(s)
- G Yadirgi
- Division of Bacteriology, National Institute for Biological Standards and Control, a center of the Medicines and Healthcare Products Regulatory Agency, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.
| | - P Stickings
- Division of Bacteriology, National Institute for Biological Standards and Control, a center of the Medicines and Healthcare Products Regulatory Agency, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.
| | - S Rajagopal
- Division of Bacteriology, National Institute for Biological Standards and Control, a center of the Medicines and Healthcare Products Regulatory Agency, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.
| | - Y Liu
- Division of Bacteriology, National Institute for Biological Standards and Control, a center of the Medicines and Healthcare Products Regulatory Agency, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.
| | - D Sesardic
- Division of Bacteriology, National Institute for Biological Standards and Control, a center of the Medicines and Healthcare Products Regulatory Agency, South Mimms, Potters Bar, Hertfordshire EN6 3QG, UK.
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Genetically engineered red cells expressing single domain camelid antibodies confer long-term protection against botulinum neurotoxin. Nat Commun 2017; 8:423. [PMID: 28871080 PMCID: PMC5583347 DOI: 10.1038/s41467-017-00448-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 06/08/2017] [Indexed: 12/12/2022] Open
Abstract
A short half-life in the circulation limits the application of therapeutics such as single-domain antibodies (VHHs). We utilize red blood cells to prolong the circulatory half-life of VHHs. Here we present VHHs against botulinum neurotoxin A (BoNT/A) on the surface of red blood cells by expressing chimeric proteins of VHHs with Glycophorin A or Kell. Mice whose red blood cells carry the chimeric proteins exhibit resistance to 10,000 times the lethal dose (LD50) of BoNT/A, and transfusion of these red blood cells into naive mice affords protection for up to 28 days. We further utilize an improved CD34+ culture system to engineer human red blood cells that express these chimeric proteins. Mice transfused with these red blood cells are resistant to highly lethal doses of BoNT/A. We demonstrate that engineered red blood cells expressing VHHs can provide prolonged prophylactic protection against bacterial toxins without inducing inhibitory immune responses and illustrates the potentially broad translatability of our strategy for therapeutic applications. The therapeutic use of single-chain antibodies (VHHs) is limited by their short half-life in the circulation. Here the authors engineer mouse and human red blood cells to express VHHs against botulinum neurotoxin A (BoNT/A) on their surface and show that an infusion of these cells into mice confers long lasting protection against a high dose of BoNT/A.
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29
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Zanetti G, Sikorra S, Rummel A, Krez N, Duregotti E, Negro S, Henke T, Rossetto O, Binz T, Pirazzini M. Botulinum neurotoxin C mutants reveal different effects of syntaxin or SNAP-25 proteolysis on neuromuscular transmission. PLoS Pathog 2017; 13:e1006567. [PMID: 28800600 PMCID: PMC5568444 DOI: 10.1371/journal.ppat.1006567] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 08/23/2017] [Accepted: 08/03/2017] [Indexed: 11/30/2022] Open
Abstract
Botulinum neurotoxin serotype C (BoNT/C) is a neuroparalytic toxin associated with outbreaks of animal botulism, particularly in birds, and is the only BoNT known to cleave two different SNARE proteins, SNAP-25 and syntaxin. BoNT/C was shown to be a good substitute for BoNT/A1 in human dystonia therapy because of its long lasting effects and absence of neuromuscular damage. Two triple mutants of BoNT/C, namely BoNT/C S51T/R52N/N53P (BoNT/C α-51) and BoNT/C L200W/M221W/I226W (BoNT/C α-3W), were recently reported to selectively cleave syntaxin and have been used here to evaluate the individual contribution of SNAP-25 and syntaxin cleavage to the effect of BoNT/C in vivo. Although BoNT/C α-51 and BoNT/C α-3W toxins cleave syntaxin with similar efficiency, we unexpectedly found also cleavage of SNAP-25, although to a lesser extent than wild type BoNT/C. Interestingly, the BoNT/C mutants exhibit reduced lethality compared to wild type toxin, a result that correlated with their residual activity against SNAP-25. In spite of this, a local injection of BoNT/C α-51 persistently impairs neuromuscular junction activity. This is due to an initial phase in which SNAP-25 cleavage causes a complete blockade of neurotransmission, and to a second phase of incomplete impairment ascribable to syntaxin cleavage. Together, these results indicate that neuroparalysis of BoNT/C at the neuromuscular junction is due to SNAP-25 cleavage, while the proteolysis of syntaxin provides a substantial, but incomplete, neuromuscular impairment. In light of this evidence, we discuss a possible clinical use of BoNT/C α-51 as a botulinum neurotoxin endowed with a wide safety margin and a long lasting effect. The seven established Botulinum Neurotoxins serotypes (BoNT/A to G) and the many BoNT subtypes, the causative agents of botulism, are the most poisonous substances known (lethal doses in the low ng/kg range). Due to their toxicological properties, BoNTs are Janus-faced toxins: potent pathogenic factors and potential bioterrorism agents as well as safe and efficacious therapeutics. BoNTs exert their neuroparalytic action by cleaving SNARE proteins, either SNAP-25 or synaptobrevin/VAMP, which mediate neurotransmitter release at the neuromuscular junction; BoNT/C is the only serotype shown to cleave SNAP-25 and syntaxin-1 in vitro. Our study shows for the first time that this parallel cleavage also occurs in vivo. By using mutated toxins reported to be syntaxin-selective, we found that SNAP-25 proteolysis at the neuromuscular junction is the key determinant of BoNT/C lethality as it completely blocks nerve-muscle transmission. Conversely, syntaxin-1 cleavage only attenuates nerve terminal activity without inactivating the synapse, leading to only a partial decrease of neuromuscular functionality. As a result, the BoNT/C mutants have dramatically reduced lethality, but still modulate neuromuscular junction activity upon intramuscular injection. This aspect is particularly relevant considering the possible use of syntaxin-specific BoNT/C derivatives to improve the present clinical utilization of BoNTs.
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Affiliation(s)
- Giulia Zanetti
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Stefan Sikorra
- Institut für Zellbiochemie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Andreas Rummel
- Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Nadja Krez
- Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Elisa Duregotti
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Samuele Negro
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Tina Henke
- Institut für Zellbiochemie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Ornella Rossetto
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Thomas Binz
- Institut für Zellbiochemie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Marco Pirazzini
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- * E-mail:
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30
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Wang D, Baudys J, Hoyt KM, Barr JR, Kalb SR. Further optimization of peptide substrate enhanced assay performance for BoNT/A detection by MALDI-TOF mass spectrometry. Anal Bioanal Chem 2017; 409:4779-4786. [PMID: 28573317 PMCID: PMC5519644 DOI: 10.1007/s00216-017-0421-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 05/04/2017] [Accepted: 05/16/2017] [Indexed: 02/07/2023]
Abstract
Rapid and sensitive detection of botulinum neurotoxins (BoNTs), which cause botulism, is essential in a public health emergency or bioterrorism event. We have previously developed a mass spectrometry (MS)-based functional method, Endopep-MS assay, for the fast detection and differentiation of all BoNT serotypes by affinity enriching the toxin and detecting the serotype-specific cleavage products of peptide substrates derived from the in vivo targets. To improve the performance of the Endopep-MS assay, we report here the further optimization of the peptide substrate for the detection of serotype A botulinum neurotoxins. An increased substrate cleavage was achieved by extending the original peptide N-terminus with optimized amino acid sequence, increasing the detection sensitivity of the method. In addition, the resistance of the substrate to nonspecific hydrolysis was dramatically improved by selectively substituting amino acids at the scissile bond and various other positions of the extended peptide. Moreover, incorporating the N-terminal hydrophobic residues dramatically improved the relative intensity of the cleavage products in the mass spectra. This allowed easy detection of the cleavage products, further enhancing the performance of the assay. The limit of detection for spiked serum sample was enhanced from 0.5 to 0.1 mouseLD50 and from 0.5 to 0.2 mouseLD50 for spiked stool. Mass spectra of optimized and old peptide substrates with BoNT/A ![]()
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Affiliation(s)
- Dongxia Wang
- National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway, NE, Atlanta, GA, 30341, USA
| | - Jakub Baudys
- National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway, NE, Atlanta, GA, 30341, USA
| | - Kaitlin M Hoyt
- National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway, NE, Atlanta, GA, 30341, USA
| | - John R Barr
- National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway, NE, Atlanta, GA, 30341, USA
| | - Suzanne R Kalb
- National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway, NE, Atlanta, GA, 30341, USA.
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Pirazzini M, Rossetto O, Eleopra R, Montecucco C. Botulinum Neurotoxins: Biology, Pharmacology, and Toxicology. Pharmacol Rev 2017; 69:200-235. [PMID: 28356439 PMCID: PMC5394922 DOI: 10.1124/pr.116.012658] [Citation(s) in RCA: 410] [Impact Index Per Article: 58.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The study of botulinum neurotoxins (BoNT) is rapidly progressing in many aspects.
Novel BoNTs are being discovered owing to next generation sequencing, but their
biologic and pharmacological properties remain largely unknown. The molecular
structure of the large protein complexes that the toxin forms with accessory
proteins, which are included in some BoNT type A1 and B1 pharmacological
preparations, have been determined. By far the largest effort has been dedicated to
the testing and validation of BoNTs as therapeutic agents in an ever increasing
number of applications, including pain therapy. BoNT type A1 has been also exploited
in a variety of cosmetic treatments, alone or in combination with other agents, and
this specific market has reached the size of the one dedicated to the treatment of
medical syndromes. The pharmacological properties and mode of action of BoNTs have
shed light on general principles of neuronal transport and protein-protein
interactions and are stimulating basic science studies. Moreover, the wide array of
BoNTs discovered and to be discovered and the production of recombinant BoNTs endowed
with specific properties suggest novel uses in therapeutics with increasing
disease/symptom specifity. These recent developments are reviewed here to provide an
updated picture of the biologic mechanism of action of BoNTs, of their increasing use
in pharmacology and in cosmetics, and of their toxicology.
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Affiliation(s)
- Marco Pirazzini
- Department of Biomedical Sciences, University of Padova, Italy (M.P., O.R., C.M.); Neurologic Department, University-Hospital S. Maria della Misericordia, Udine, Italy (R.E.); and Consiglio Nazionale delle Ricerche, Institute of Neuroscience, University of Padova, Italy (C.M.)
| | - Ornella Rossetto
- Department of Biomedical Sciences, University of Padova, Italy (M.P., O.R., C.M.); Neurologic Department, University-Hospital S. Maria della Misericordia, Udine, Italy (R.E.); and Consiglio Nazionale delle Ricerche, Institute of Neuroscience, University of Padova, Italy (C.M.)
| | - Roberto Eleopra
- Department of Biomedical Sciences, University of Padova, Italy (M.P., O.R., C.M.); Neurologic Department, University-Hospital S. Maria della Misericordia, Udine, Italy (R.E.); and Consiglio Nazionale delle Ricerche, Institute of Neuroscience, University of Padova, Italy (C.M.)
| | - Cesare Montecucco
- Department of Biomedical Sciences, University of Padova, Italy (M.P., O.R., C.M.); Neurologic Department, University-Hospital S. Maria della Misericordia, Udine, Italy (R.E.); and Consiglio Nazionale delle Ricerche, Institute of Neuroscience, University of Padova, Italy (C.M.)
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32
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Santos TC, Wierda K, Broeke JH, Toonen RF, Verhage M. Early Golgi Abnormalities and Neurodegeneration upon Loss of Presynaptic Proteins Munc18-1, Syntaxin-1, or SNAP-25. J Neurosci 2017; 37:4525-4539. [PMID: 28348137 PMCID: PMC6596660 DOI: 10.1523/jneurosci.3352-16.2017] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Revised: 02/07/2017] [Accepted: 03/07/2017] [Indexed: 11/21/2022] Open
Abstract
The loss of presynaptic proteins Munc18-1, syntaxin-1, or SNAP-25 is known to produce cell death, but the underlying features have not been compared experimentally. Here, we investigated these features in cultured mouse CNS and DRG neurons. Side-by-side comparisons confirmed massive cell death, before synaptogenesis, within 1-4 DIV upon loss of t-SNAREs (syntaxin-1, SNAP-25) or Munc18-1, but not v-SNAREs (synaptobrevins/VAMP1/2/3 using tetanus neurotoxin (TeNT), also in TI-VAMP/VAMP7 knock-out (KO) neurons). A condensed cis-Golgi was the first abnormality observed upon Munc18-1 or SNAP-25 loss within 3 DIV. This phenotype was distinct from the Golgi fragmentation observed in apoptosis. Cell death was too rapid after syntaxin-1 loss to study Golgi abnormalities. Syntaxin-1 and Munc18-1 depend on each other for normal cellular levels. We observed that endogenous syntaxin-1 accumulates at the Golgi of Munc18-1 KO neurons. However, expression of a non-neuronal Munc18 isoform that does not bind syntaxin-1, Munc18-3, in Munc18-1 KO neurons prevented cell death and restored normal cis-Golgi morphology, but not synaptic transmission or syntaxin-1 targeting. Finally, we observed that DRG neurons are the only Munc18-1 KO neurons that do not degenerate in vivo or in vitro In these neurons, cis-Golgi abnormalities were less severe, with no changes in Golgi shape. Together, these data demonstrate that cell death upon Munc18-1, syntaxin-1, or SNAP-25 loss occurs via a degenerative pathway unrelated to the known synapse function of these proteins and involving early cis-Golgi abnormalities, distinct from apoptosis.SIGNIFICANCE STATEMENT This study provides new insights in a neurodegeneration pathway triggered by the absence of specific proteins involved in synaptic transmission (syntaxin-1, Munc18-1, SNAP-25), whereas other proteins involved in the same molecular process (synaptobrevins, Munc13-1/2) do not cause degeneration. Massive cell death occurs in cultured neurons upon depleting syntaxin-1, Munc18-1, and/or SNAP-25, well before synapse formation. This study characterizes several relevant cellular phenotypes, especially early cis-Golgi abnormalities, distinct from abnormalities observed during apoptosis, and rules out several other phenotypes as causal (defects in syntaxin-1 targeting and synaptic transmission). As proteins, such as syntaxin-1, Munc18-1, or SNAP-25, modulate α-synuclein neuropathy and/or are dysregulated in Alzheimer's disease, understanding this type of neurodegeneration may provide new links between synaptic defects and neurodegeneration in humans.
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Affiliation(s)
| | | | - Jurjen H Broeke
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV Amsterdam, The Netherlands
| | | | - Matthijs Verhage
- Department of Functional Genomics and
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research, VU University Amsterdam and VU Medical Center, 1081 HV Amsterdam, The Netherlands
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Jorgačevski J, Potokar M, Kreft M, Guček A, Mothet JP, Zorec R. Astrocytic Vesicle-based Exocytosis in Cultures and Acutely Isolated Hippocampal Rodent Slices. J Neurosci Res 2017; 95:2152-2158. [PMID: 28370180 DOI: 10.1002/jnr.24051] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 02/02/2017] [Accepted: 02/22/2017] [Indexed: 01/05/2023]
Abstract
Astrocytes are excitable neural cells that contribute to brain information processing via bidirectional communication with neurons. This involves the release of gliosignaling molecules that affect synapses patterning and activity. Mechanisms mediating the release of these molecules likely consist of non-vesicular and vesicular-based mechanisms. It is the vesicle-based regulated exocytosis that is an evolutionary more complex process. It is well established that the release of gliosignaling molecules has profound effects on information processing in different brain regions (e.g., hippocampal astrocytes contribute to long-term potentiation [LTP]), which has traditionally been considered as one of the cellular mechanisms underlying learning and memory. However, the paradigm of vesicle-based regulated release of gliosignaling molecules from astrocytes is still far from being unanimously accepted. One of the most important questions is to what extent can the conclusions obtained from cultured astrocytes be translated to in vivo conditions. Here, we overview the properties of vesicle mobility and their fusion with the plasma membrane in cultured astrocytes and compare these parameters to those recorded in astrocytes from acute brain hippocampal slices. The results from both experimental models are similar, which validates experiments on isolated astrocytes and further supports arguments in favor of in vivo vesicle-based exocytotic release of gliosignaling molecules. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Jernej Jorgačevski
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia.,Celica Biomedical, Tehnološki Park 24, 1000, Ljubljana, Slovenia
| | - Maja Potokar
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia.,Celica Biomedical, Tehnološki Park 24, 1000, Ljubljana, Slovenia
| | - Marko Kreft
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia.,Celica Biomedical, Tehnološki Park 24, 1000, Ljubljana, Slovenia.,Department of Biology, Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000, Ljubljana, Slovenia
| | - Alenka Guček
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia
| | - Jean-Pierre Mothet
- Team Gliotransmission and Synaptopathies, Aix-Marseille Université, CNRS, CRN2M UMR7286, Marseille, France
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia.,Celica Biomedical, Tehnološki Park 24, 1000, Ljubljana, Slovenia
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Guček A, Jorgačevski J, Singh P, Geisler C, Lisjak M, Vardjan N, Kreft M, Egner A, Zorec R. Dominant negative SNARE peptides stabilize the fusion pore in a narrow, release-unproductive state. Cell Mol Life Sci 2016; 73:3719-31. [PMID: 27056575 PMCID: PMC11108528 DOI: 10.1007/s00018-016-2213-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 03/05/2016] [Accepted: 03/29/2016] [Indexed: 01/18/2023]
Abstract
Key support for vesicle-based release of gliotransmitters comes from studies of transgenic mice with astrocyte-specific expression of a dominant-negative domain of synaptobrevin 2 protein (dnSNARE). To determine how this peptide affects exocytosis, we used super-resolution stimulated emission depletion microscopy and structured illumination microscopy to study the anatomy of single vesicles in astrocytes. Smaller vesicles contained amino acid and peptidergic transmitters and larger vesicles contained ATP. Discrete increases in membrane capacitance, indicating single-vesicle fusion, revealed that astrocyte stimulation increases the frequency of predominantly transient fusion events in smaller vesicles, whereas larger vesicles transitioned to full fusion. To determine whether this reflects a lower density of SNARE proteins in larger vesicles, we treated astrocytes with botulinum neurotoxins D and E, which reduced exocytotic events of both vesicle types. dnSNARE peptide stabilized the fusion-pore diameter to narrow, release-unproductive diameters in both vesicle types, regardless of vesicle diameter.
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Affiliation(s)
- Alenka Guček
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - Jernej Jorgačevski
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, University of Ljubljana, 1000, Ljubljana, Slovenia
- Celica BIOMEDICAL, 1000, Ljubljana, Slovenia
| | - Priyanka Singh
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - Claudia Geisler
- Department of Optical Nanoscopy, Laser-Laboratory Göttingen e.V., 37077, Göttingen, Germany
| | - Marjeta Lisjak
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - Nina Vardjan
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, University of Ljubljana, 1000, Ljubljana, Slovenia
- Celica BIOMEDICAL, 1000, Ljubljana, Slovenia
| | - Marko Kreft
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, University of Ljubljana, 1000, Ljubljana, Slovenia
- Celica BIOMEDICAL, 1000, Ljubljana, Slovenia
- Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - Alexander Egner
- Department of Optical Nanoscopy, Laser-Laboratory Göttingen e.V., 37077, Göttingen, Germany
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, University of Ljubljana, 1000, Ljubljana, Slovenia.
- Celica BIOMEDICAL, 1000, Ljubljana, Slovenia.
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Pero R, Coretti L, Lembo F. Botulinum Toxin A for Controlling Obesity. Toxins (Basel) 2016; 8:E281. [PMID: 27681739 PMCID: PMC5086641 DOI: 10.3390/toxins8100281] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 09/20/2016] [Accepted: 09/20/2016] [Indexed: 01/09/2023] Open
Abstract
Rapid growth of the overweight population and the number of obese individuals in recent decades suggests that current strategies based on diet, exercise, and pharmacological knowledge are not sufficient to address this epidemic. Obesity is the result of a high caloric intake and energy storage, not counterbalanced by an equally important energy expense. Botulinum toxin type A (BoNT-A) use is rapidly expanding to include treatment of a variety of ophthalmological, gastrointestinal, urological, orthopedic, dermatological, secretory, painful, and cosmetic disorders. Many studies evaluating the effect of BoNT-A in gastric antrum e/o fundus for the treatment of obesity have been published. This treatment modality was based on the observation that gastric injection of BoNT-A in laparatomized rats induced a significant reduction of food intake and body weight. These studies have been published yielding debated results. Differences in the selection of patients, the doses of BoNT-A, the method of administration of the toxin, and the instruments of evaluation of some parameters among these studies may be the cause. In this review, it will study the state-of-the-art use of BoNT-A in obesity basic science models and review the clinical evidence on the therapeutic applications of BoNT-A for obesity.
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Affiliation(s)
- Raffaela Pero
- Department of Molecular Medicine and Medical Biotechnology, University of Naples "Federico II", Naples 80131, Italy.
| | - Lorena Coretti
- Department of Molecular Medicine and Medical Biotechnology, University of Naples "Federico II", Naples 80131, Italy.
| | - Francesca Lembo
- Dipartimento di Farmacia, Università degli Studi di Napoli "Federico II", via D. Montesano 47, Naples 80131, Italy.
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Kasula R, Chai YJ, Bademosi AT, Harper CB, Gormal RS, Morrow IC, Hosy E, Collins BM, Choquet D, Papadopulos A, Meunier FA. The Munc18-1 domain 3a hinge-loop controls syntaxin-1A nanodomain assembly and engagement with the SNARE complex during secretory vesicle priming. J Cell Biol 2016; 214:847-58. [PMID: 27646276 PMCID: PMC5037406 DOI: 10.1083/jcb.201508118] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Accepted: 08/24/2016] [Indexed: 12/12/2022] Open
Abstract
Kasula et al. use single-molecule imaging to reveal the diffusional signature for the SNARE proteins Munc18-1 and syntaxin-1A during secretory vesicle priming. The authors show that a conformational change in the Munc18-1 domain 3a hinge-loop regulates engagement of syntaxin-1A in the SNARE complex. Munc18-1 and syntaxin-1A control SNARE-dependent neuroexocytosis and are organized in nanodomains on the plasma membrane of neurons and neurosecretory cells. Deciphering the intra- and intermolecular steps via which they prepare secretory vesicles (SVs) for fusion is key to understanding neuronal and hormonal communication. Here, we demonstrate that expression of a priming-deficient mutant lacking 17 residues of the domain 3a hinge-loop (Munc18-1Δ317-333) in PC12 cells engineered to knockdown Munc18-1/2 markedly prolonged SV docking. Single-molecule analysis revealed nonhomogeneous diffusion of Munc18-1 and syntaxin-1A in and out of partially overlapping nanodomains. Whereas Munc18-1WT mobility increased in response to stimulation, syntaxin-1A became less mobile. These Munc18-1 and syntaxin-1A diffusional switches were blocked by the expression of Munc18-1Δ317-333, suggesting that a conformational change in the Munc18-1 hinge-loop controls syntaxin-1A and subsequent SNARE complex assembly. Accordingly, syntaxin-1A confinement was prevented by expression of botulinum neurotoxin type E. The Munc18-1 domain 3a hinge-loop therefore controls syntaxin-1A engagement into SNARE complex formation during priming.
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Affiliation(s)
- Ravikiran Kasula
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Ye Jin Chai
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Adekunle T Bademosi
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Callista B Harper
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Rachel S Gormal
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Isabel C Morrow
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Eric Hosy
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, 33077 Bordeaux, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5297, 33077 Bordeaux, France
| | - Brett M Collins
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Daniel Choquet
- Interdisciplinary Institute for Neuroscience, University of Bordeaux, 33077 Bordeaux, France Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5297, 33077 Bordeaux, France Bordeaux Imaging Center, Unité Mixte de Service 3420, Centre National de la Recherche Scientifique, US4 Institut National de la Santé et de la Recherche Médicale, University of Bordeaux, 33077 Bordeaux, France
| | - Andreas Papadopulos
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Frédéric A Meunier
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane, Queensland 4072, Australia
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Toft-Bertelsen TL, Ziomkiewicz I, Houy S, Pinheiro PS, Sørensen JB. Regulation of Ca2+ channels by SNAP-25 via recruitment of syntaxin-1 from plasma membrane clusters. Mol Biol Cell 2016; 27:3329-3341. [PMID: 27605709 PMCID: PMC5170865 DOI: 10.1091/mbc.e16-03-0184] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 09/01/2016] [Indexed: 12/20/2022] Open
Abstract
SNAP-25 regulates Ca2+ channels in an unknown manner. Endogenous and exogenous SNAP-25 inhibit Ca2+ currents indirectly by recruiting syntaxin-1 from clusters on the plasma membrane, thereby making it available for Ca2+ current inhibition. Thus the cell can regulate Ca2+ influx by expanding or contracting syntaxin-1 clusters. SNAP-25 regulates Ca2+ channels, with potentially important consequences for diseases involving an aberrant SNAP-25 expression level. How this regulation is executed mechanistically remains unknown. We investigated this question in mouse adrenal chromaffin cells and found that SNAP-25 inhibits Ca2+ currents, with the B-isoform being more potent than the A-isoform, but not when syntaxin-1 is cleaved by botulinum neurotoxin C. In contrast, syntaxin-1 inhibits Ca2+ currents independently of SNAP-25. Further experiments using immunostaining showed that endogenous or exogenous SNAP-25 expression recruits syntaxin-1 from clusters on the plasma membrane, thereby increasing the immunoavailability of syntaxin-1 and leading indirectly to Ca2+ current inhibition. Expression of Munc18-1, which recruits syntaxin-1 within the exocytotic pathway, does not modulate Ca2+ channels, whereas overexpression of the syntaxin-binding protein Doc2B or ubMunc13-2 increases syntaxin-1 immunoavailability and concomitantly down-regulates Ca2+ currents. Similar findings were obtained upon chemical cholesterol depletion, leading directly to syntaxin-1 cluster dispersal and Ca2+ current inhibition. We conclude that clustering of syntaxin-1 allows the cell to maintain a high syntaxin-1 expression level without compromising Ca2+ influx, and recruitment of syntaxin-1 from clusters by SNAP-25 expression makes it available for regulating Ca2+ channels. This mechanism potentially allows the cell to regulate Ca2+ influx by expanding or contracting syntaxin-1 clusters.
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Affiliation(s)
- Trine Lisberg Toft-Bertelsen
- Neurosecretion Group, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Iwona Ziomkiewicz
- Neurosecretion Group, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Sébastien Houy
- Neurosecretion Group, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Paulo S Pinheiro
- Neurosecretion Group, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Jakob B Sørensen
- Neurosecretion Group, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
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Azarnia Tehran D, Pirazzini M, Leka O, Mattarei A, Lista F, Binz T, Rossetto O, Montecucco C. Hsp90 is involved in the entry of clostridial neurotoxins into the cytosol of nerve terminals. Cell Microbiol 2016; 19. [DOI: 10.1111/cmi.12647] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 07/06/2016] [Accepted: 07/08/2016] [Indexed: 12/31/2022]
Affiliation(s)
- Domenico Azarnia Tehran
- Department of Biomedical Sciences; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
| | - Marco Pirazzini
- Department of Biomedical Sciences; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
| | - Oneda Leka
- Department of Biomedical Sciences; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
| | - Andrea Mattarei
- Department of Chemical Sciences; University of Padova; Via F. Marzolo 1 35131 Padova Italy
| | - Florigio Lista
- Histology and Molecular Biology Section; Army Medical and Veterinary Research Center; Via Santo Stefano Rotondo 4 00184 Rome Italy
| | - Thomas Binz
- Medizinische Hochschule Hannover; Institut für Physiologische Chemie OE4310; 30625 Hannover Germany
| | - Ornella Rossetto
- Department of Biomedical Sciences; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
| | - Cesare Montecucco
- Department of Biomedical Sciences; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
- National Research Institute of Neuroscience; University of Padova; Via Ugo Bassi 58/B 35121 Padova Italy
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Chatla K, Gaunt PS, Petrie-Hanson L, Ford L, Hanson LA. Zebrafish Sensitivity to Botulinum Neurotoxins. Toxins (Basel) 2016; 8:toxins8050132. [PMID: 27153088 PMCID: PMC4885047 DOI: 10.3390/toxins8050132] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 04/12/2016] [Accepted: 04/20/2016] [Indexed: 02/03/2023] Open
Abstract
Botulinum neurotoxins (BoNT) are the most potent known toxins. The mouse LD50 assay is the gold standard for testing BoNT potency, but is not sensitive enough to detect the extremely low levels of neurotoxin that may be present in the serum of sensitive animal species that are showing the effects of BoNT toxicity, such as channel catfish affected by visceral toxicosis of catfish. Since zebrafish are an important animal model for diverse biomedical and basic research, they are readily available and have defined genetic lines that facilitate reproducibility. This makes them attractive for use as an alternative bioassay organism. The utility of zebrafish as a bioassay model organism for BoNT was investigated. The 96 h median immobilizing doses of BoNT/A, BoNT/C, BoNT/E, and BoNT/F for adult male Tübingen strain zebrafish (0.32 g mean weight) at 25 °C were 16.31, 124.6, 4.7, and 0.61 picograms (pg)/fish, respectively. These findings support the use of the zebrafish-based bioassays for evaluating the presence of BoNT/A, BoNT/E, and BoNT/F. Evaluating the basis of the relatively high resistance of zebrafish to BoNT/C and the extreme sensitivity to BoNT/F may reveal unique functional patterns to the action of these neurotoxins.
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Affiliation(s)
- Kamalakar Chatla
- Department of Basic Science, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA.
| | - Patricia S Gaunt
- Thad Cochran National Warmwater Aquaculture Center, College of Veterinary Medicine, Mississippi State University, Stoneville, MS 38756, USA.
| | - Lora Petrie-Hanson
- Department of Basic Science, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA.
| | - Lorelei Ford
- Department of Basic Science, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA.
| | - Larry A Hanson
- Department of Basic Science, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762, USA.
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Galazka M, Soszynski D, Dmitruk K. Central Action of Botulinum Toxin Type A – Is It Possible? NEUROPHYSIOLOGY+ 2015. [DOI: 10.1007/s11062-015-9540-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Sikorra S, Litschko C, Müller C, Thiel N, Galli T, Eichner T, Binz T. Identification and Characterization of Botulinum Neurotoxin A Substrate Binding Pockets and Their Re-Engineering for Human SNAP-23. J Mol Biol 2015; 428:372-384. [PMID: 26523682 DOI: 10.1016/j.jmb.2015.10.024] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 10/13/2015] [Accepted: 10/25/2015] [Indexed: 11/26/2022]
Abstract
Botulinum neurotoxins (BoNTs) are highly potent bacterial proteins that block neurotransmitter release at the neuromuscular junction by cleaving SNAREs (soluble N-ethyl maleimide sensitive factor attachment protein receptors). However, their serotype A (BoNT/A) that cleaves SNAP-25 (synaptosomal-associated protein of 25 kDa) has also been an established pharmaceutical for treatment of medical conditions that rely on hyperactivity of cholinergic nerve terminals for 25 years. The expansion of its use to a variety of further medical conditions associated with hypersecretion components is prevented partly because the involved SNARE isoforms are not cleaved. Therefore, we examined by mutational analyses the reason for the resistance of human SNAP-23, an isoform of SNAP-25. We show that replacement of 10 SNAP-23 residues with their SNAP-25 counterparts effects SNAP-25-like cleavability. Conversely, transfer of each of the replaced SNAP-23 residues to SNAP-25 drastically decreased the cleavability of SNAP-25. By means of the existing SNAP-25-toxin co-crystal structure, molecular dynamics simulations, and corroborative mutagenesis studies, the appropriate binding pockets for these residues in BoNT/A were characterized. Systematic mutagenesis of two major BoNT/A binding pockets was conducted in order to adapt these pockets to corresponding amino acids of human SNAP-23. Human SNAP-23 cleaving mutants were isolated using a newly established yeast-based screening system. This method may be useful for engineering novel BoNT/A pharmaceuticals for the treatment of diseases that rely on SNAP-23-mediated hypersecretion.
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Affiliation(s)
- Stefan Sikorra
- Institut für Physiologische Chemie, OE 4310, Medizinische Hochschule Hannover, D-30623 Hannover, Germany
| | - Christa Litschko
- Institut für Physiologische Chemie, OE 4310, Medizinische Hochschule Hannover, D-30623 Hannover, Germany
| | - Carina Müller
- Institut für Physiologische Chemie, OE 4310, Medizinische Hochschule Hannover, D-30623 Hannover, Germany
| | - Nadine Thiel
- Institut für Physiologische Chemie, OE 4310, Medizinische Hochschule Hannover, D-30623 Hannover, Germany
| | - Thierry Galli
- Sorbonne Paris Cité, Université Paris Diderot, Institut Jacques Monod, CNRS UMR 7592, INSERM ERL U950, F-75013 Paris, France
| | - Timo Eichner
- Department of Biochemistry, Brandeis University, Waltham, MA 02454, USA
| | - Thomas Binz
- Institut für Physiologische Chemie, OE 4310, Medizinische Hochschule Hannover, D-30623 Hannover, Germany.
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Rummel A. The long journey of botulinum neurotoxins into the synapse. Toxicon 2015; 107:9-24. [PMID: 26363288 DOI: 10.1016/j.toxicon.2015.09.009] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 08/27/2015] [Accepted: 09/08/2015] [Indexed: 01/09/2023]
Abstract
Botulinum neurotoxins (BoNT) cause the disease botulism, a flaccid paralysis of the muscle. They are also very effective, widely used medicines applied locally in sub-nanogram quantities. BoNTs are released together with several non-toxic, associated proteins as progenitor toxin complexes (PCT) by Clostridium botulinum to become highly potent oral poisons ingested via contaminated food. They block the neurotransmission in susceptible animals and humans already in nanogram quantities due to their specific ability to enter motoneurons and to cleave only selected neuronal proteins involved in neuroexocytosis. BoNTs have developed a sophisticated strategy to passage the gastrointestinal tract and to be absorbed in the intestine of the host to finally attack neurons. A non-toxic non-hemagglutinin (NTNHA) forms a binary complex with BoNT to protect it from gastrointestinal degradation. This binary M-PTC is one component of the bi-modular 14-subunit ∼760 kDa large progenitor toxin complex. The other component is the structurally and functionally independent dodecameric hemagglutinin (HA) complex which facilitates the absorption on the intestinal epithelium by glycan binding. Subsequent to its transcytosis the HA complex disrupts the tight junction of the intestinal barrier from the basolateral side by binding to E-cadherin. Now, the L-PTC can also enter the circulation by paracellular routes in much larger quantities. From here, the dissociated BoNTs reach the neuromuscular junction and accumulate via interaction with polysialo gangliosides, complex glycolipids, on motoneurons at the neuromuscular junction. Subsequently, additional specific binding to luminal segments of synaptic vesicles proteins like SV2 and synaptotagmin leads to their uptake. Finally, the neurotoxins shut down the synaptic vesicle cycle, which they had exploited before to enter their target cells, via specific cleavage of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins, which constitute the core components of the cellular membrane fusion machinery.
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Affiliation(s)
- Andreas Rummel
- Institut für Toxikologie, Medizinische Hochschule Hannover, 30623 Hannover, Germany.
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da Silva LB, Poulsen JN, Arendt-Nielsen L, Gazerani P. Botulinum neurotoxin type A modulates vesicular release of glutamate from satellite glial cells. J Cell Mol Med 2015; 19:1900-9. [PMID: 25754332 PMCID: PMC4549040 DOI: 10.1111/jcmm.12562] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Accepted: 01/20/2015] [Indexed: 01/06/2023] Open
Abstract
This study investigated the presence of cell membrane docking proteins synaptosomal-associated protein, 25 and 23 kD (SNAP-25 and SNAP-23) in satellite glial cells (SGCs) of rat trigeminal ganglion; whether cultured SGCs would release glutamate in a time- and calcium-dependent manner following calcium-ionophore ionomycin stimulation; and if botulinum neurotoxin type A (BoNTA), in a dose-dependent manner, could block or decrease vesicular release of glutamate. SGCs were isolated from the trigeminal ganglia (TG) of adult Wistar rats and cultured for 7 days. The presence of SNAPs in TG sections and isolated SGCs were investigated using immunohistochemistry and immunocytochemistry, respectively. SGCs were stimulated with ionomycin (5 μM for 4, 8, 12 and 30 min.) to release glutamate. SGCs were then pre-incubated with BoNTA (24 hrs with 0.1, 1, 10 and 100 pM) to investigate if BoNTA could potentially block ionomycin-stimulated glutamate release. Glutamate concentrations were measured by ELISA. SNAP-25 and SNAP-23 were present in SGCs in TG sections and in cultured SGCs. Ionomycin significantly increased glutamate release from cultured SGCs 30 min. following the treatment (P < 0.001). BoNTA (100 pM) significantly decreased glutamate release (P < 0.01). Results from this study demonstrated that SGCs, when stimulated with ionomycin, released glutamate that was inhibited by BoNTA, possibly through cleavage of SNAP-25 and/or SNAP-23. These novel findings demonstrate the existence of vesicular glutamate release from SGCs, which could potentially play a role in the trigeminal sensory transmission. In addition, interaction of BoNTA with non-neuronal cells at the level of TG suggests a potential analgesic mechanism of action of BoNTA.
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Affiliation(s)
- Larissa Bittencourt da Silva
- Center for Sensory - Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg UniversityAalborg East, Denmark
| | - Jeppe Nørgaard Poulsen
- Center for Sensory - Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg UniversityAalborg East, Denmark
| | - Lars Arendt-Nielsen
- Center for Sensory - Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg UniversityAalborg East, Denmark
| | - Parisa Gazerani
- Center for Sensory - Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg UniversityAalborg East, Denmark
- Laboratory for Cancer Biology, Biomedicine, Department of Health Science and Technology, Faculty of Medicine, Aalborg UniversityAalborg East, Denmark
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Atassi MZ. Molecular basis of immunogenicity to botulinum neurotoxins and uses of the defined antigenic regions. Toxicon 2015; 107:50-8. [PMID: 26086358 DOI: 10.1016/j.toxicon.2015.06.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 06/11/2015] [Indexed: 12/14/2022]
Abstract
Intensive research in this laboratory over the last 19 years has aimed at understanding the molecular bases for immune recognition of botulinum neurotoxin, types A and B and the role of anti-toxin immune responses in defense against the toxin. Using 92 synthetic 19-residue peptides that overlapped by 5 residues and comprised an entire toxin (A or B) we determined the peptides' ability to bind anti-toxin Abs of human, mouse, horse and chicken. We also localized the epitopes recognized by Abs of cervical dystonia patients who developed immunoresistance to correlate toxin during treatment with BoNT/A or BoNT/B. For BoNT/A, patients' blocking Abs bound to 13 regions (5 on L and 8 on H subunit) on the surface and the response to each region was under separate MHC control. The responses were defined by the structure of the antigen and by the MHC of the host. The antigenic regions coincided or overlapped with synaptosomes (SNPS) binding regions. Antibody binding blocked the toxin's ability to bind to neuronal cells. In fact selected synthetic peptides were able to inhibit the toxin's action in vivo. A combination of three synthetic strong antigenic peptides detected blocking Abs in 88% of immunoresistant patients' sera. Administration of selected epitopes, pre-linked at their N(α) group to monomethoxyployethylene glycol, into mice with ongoing blocking anti-toxin Abs, reduced blocking Ab levels in the recipients. This may be suitable for clinical applications. Defined epitopes should also be valuable in synthetic vaccines design.
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Affiliation(s)
- M Z Atassi
- Department of Biochemistry and Molecular Biology, Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA.
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45
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Wang D, Krilich J, Baudys J, Barr JR, Kalb SR. Enhanced detection of type C botulinum neurotoxin by the Endopep-MS assay through optimization of peptide substrates. Bioorg Med Chem 2015; 23:3667-73. [PMID: 25913863 DOI: 10.1016/j.bmc.2015.04.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 03/25/2015] [Accepted: 04/03/2015] [Indexed: 10/23/2022]
Abstract
It is essential to have a simple, quick and sensitive method for the detection and quantification of botulinum neurotoxins, the most toxic substances and the causative agents of botulism. Type C botulinum neurotoxin (BoNT/C) represents one of the seven members of distinctive BoNT serotypes (A to G) that cause botulism in animals and avians. Here we report the development of optimized peptide substrates for improving the detection of BoNT/C and /CD mosaic toxins using an Endopep-MS assay, a mass spectrometry-based method that is able to rapidly and sensitively detect and differentiate all types of BoNTs by extracting the toxin with specific antibodies and detecting the unique cleavage products of peptide substrates. Based on the sequence of a short SNAP-25 peptide, we conducted optimization through a comprehensive process including length determination, terminal modification, single and multiple amino acid residue substitution, and incorporation of unnatural amino acid residues. Our data demonstrate that an optimal peptide provides a more than 200-fold improvement over the substrate currently used in the Endopep-MS assay for the detection of BoNT/C1 and /CD mosaic. Using the new substrate in a four-hour cleavage reaction, the limit of detection for the BoNT/C1 complex spiked in buffer, serum and milk samples was determined to be 0.5, 0.5 and 1mouseLD50/mL, respectively, representing a similar or higher sensitivity than that obtained by traditional mouse bioassay.
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Affiliation(s)
- Dongxia Wang
- Division of Laboratory Sciences, National Center for the Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway, Atlanta, GA 30341, United States
| | - Joan Krilich
- Division of Laboratory Sciences, National Center for the Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway, Atlanta, GA 30341, United States
| | - Jakub Baudys
- Division of Laboratory Sciences, National Center for the Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway, Atlanta, GA 30341, United States
| | - John R Barr
- Division of Laboratory Sciences, National Center for the Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway, Atlanta, GA 30341, United States
| | - Suzanne R Kalb
- Division of Laboratory Sciences, National Center for the Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway, Atlanta, GA 30341, United States.
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46
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Wang D, Krilich J, Baudys J, Barr JR, Kalb SR. Optimization of peptide substrates for botulinum neurotoxin E improves detection sensitivity in the Endopep-MS assay. Anal Biochem 2014; 468:15-21. [PMID: 25232998 DOI: 10.1016/j.ab.2014.08.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 08/20/2014] [Accepted: 08/21/2014] [Indexed: 11/17/2022]
Abstract
Botulinum neurotoxins (BoNTs) produced by Clostridium botulinum are the most poisonous substances known to humankind. It is essential to have a simple, quick, and sensitive method for the detection and quantification of botulinum toxin in various media, including complex biological matrices. Our laboratory has developed a mass spectrometry-based Endopep-MS assay that is able to rapidly detect and differentiate all types of BoNTs by extracting the toxin with specific antibodies and detecting the unique cleavage products of peptide substrates. Botulinum neurotoxin type E (BoNT/E) is a member of a family of seven distinctive BoNT serotypes (A-G) and is the causative agent of botulism in both humans and animals. To improve the sensitivity of the Endopep-MS assay, we report here the development of novel peptide substrates for the detection of BoNT/E activity through systematic and comprehensive approaches. Our data demonstrate that several optimal peptides could accomplish 500-fold improvement in sensitivity compared with the current substrate for the detection of both not-trypsin-activated and trypsin-activated BoNT/E toxin complexes. A limit of detection of 0.1 mouse LD50/ml was achieved using the novel peptide substrate in the assay to detect not-trypsin-activated BoNT/E complex spiked in serum, stool, and food samples.
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Affiliation(s)
- Dongxia Wang
- Centers for Disease Control and Prevention, Atlanta, GA 30341, USA
| | - Joan Krilich
- Battelle Memorial Institute under contract at Centers for Disease Control and Prevention, Atlanta, GA 30341, USA
| | - Jakub Baudys
- Centers for Disease Control and Prevention, Atlanta, GA 30341, USA
| | - John R Barr
- Centers for Disease Control and Prevention, Atlanta, GA 30341, USA
| | - Suzanne R Kalb
- Centers for Disease Control and Prevention, Atlanta, GA 30341, USA.
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47
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Lawrence GW, Wang J, Brin MF, Aoki KR, Wheeler L, Dolly JO. Fusion of Golgi-derived vesicles mediated by SNAP-25 is essential for sympathetic neuron outgrowth but relatively insensitive to botulinum neurotoxins in vitro. FEBS J 2014; 281:3243-60. [PMID: 24863955 DOI: 10.1111/febs.12858] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 03/28/2014] [Accepted: 05/21/2014] [Indexed: 01/12/2023]
Abstract
Sympathetic neurons ramify to innervate multiple cells in target tissues. In compartmentalized cultures of rat superior cervical ganglion neurons, cleavage of synaptosomal-associated protein of Mr = 25 000 (SNAP-25) in neurites exposed to botulinum neurotoxin type A (BoNT/A) arrested their growth and collapsed interstitial branches, but this required large, nonclinical doses. A protease-inactive mutant proved ineffective, confirming involvement of SNAP-25 in neurite extension and arborization. BoNT/C1 acted like BoNT/A, but BoNT/E caused only mild inhibition, likely due to transient SNAP-25 proteolysis. Near-total lack of susceptibility to BoNT/B or BoNT/D revealed that vesicle-associated membrane protein (VAMPs) isoforms 1-3 are not essential. Neurite length was not reduced when either BoNT/A or BoNT/C1 was applied to the somata, with no detrimental effect on neuron viability being observed. Treatments that protect cells from deprivation of nerve growth factor failed to prevent the toxin-induced loss of neurites. Inactivation of SNAP-25 caused the accumulation at neurite branch sites of Golgi-derived organelles labelled with N-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-sphingosine conjugated to bovine serum albumin, prior to the collapse of arbors. Notably, neurite growth was ~ 1000-fold less susceptible to BoNT/A than cholinergic transmission in these neurons. Accordingly, a BoNT/A acceptor synaptic vesicle protein 2 (SV2) was found to be colocalized with VAMP 1-3, but not with VAMP 7, which is implicated in the growth of neurites. In conclusion, neurites depend on SNAP-25 for extension but this is quite resistant to BoNT/A, possibly, because of a low density of SV2 at growth sites that are distant from the highly susceptible regions of neurotransmitter release.
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Affiliation(s)
- Gary W Lawrence
- International Centre for Neurotherapeutics, Dublin City University, Ireland
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48
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Kim DW, Lee SK, Ahnn J. Phenotypic effect of botulinum toxin A onCaenorhabditis elegans. Anim Cells Syst (Seoul) 2014. [DOI: 10.1080/19768354.2014.915883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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49
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Bielopolski N, Lam AD, Bar-On D, Sauer M, Stuenkel EL, Ashery U. Differential interaction of tomosyn with syntaxin and SNAP25 depends on domains in the WD40 β-propeller core and determines its inhibitory activity. J Biol Chem 2014; 289:17087-99. [PMID: 24782308 DOI: 10.1074/jbc.m113.515296] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Neuronal exocytosis depends on efficient formation of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes and is regulated by tomosyn, a SNARE-binding protein. To gain new information about tomosyn's activity, we characterized its mobility and organization on the plasma membrane (PM) in relation to other SNARE proteins and inhibition of exocytosis. By using direct stochastic optical reconstruction microscopy (dSTORM), we found tomosyn to be organized in small clusters adjacent to syntaxin clusters. In addition, we show that tomosyn is present in both syntaxin-tomosyn complexes and syntaxin-SNAP25-tomosyn complexes. Tomosyn mutants that lack residues 537-578 or 897-917 from its β-propeller core diffused faster on the PM and exhibited reduced binding to SNAP25, suggesting that these mutants shift the equilibrium between tomosyn-syntaxin-SNAP25 complexes on the PM to tomosyn-syntaxin complexes. As these deletion mutants impose less inhibition on exocytosis, we suggest that tomosyn inhibition is mediated via tomosyn-syntaxin-SNAP25 complexes and not tomosyn-syntaxin complexes. These findings characterize, for the first time, tomosyn's dynamics at the PM and its relation to its inhibition of exocytosis.
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Affiliation(s)
- Noa Bielopolski
- From the Department of Neurobiology, Life Sciences Faculty, and
| | - Alice D Lam
- the Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, and
| | - Dana Bar-On
- From the Department of Neurobiology, Life Sciences Faculty, and Sagol School of Neuroscience, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Markus Sauer
- the Department of Biotechnology and Biophysics, Julius Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Edward L Stuenkel
- the Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, and
| | - Uri Ashery
- From the Department of Neurobiology, Life Sciences Faculty, and Sagol School of Neuroscience, Tel Aviv University, 69978 Tel Aviv, Israel,
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50
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Rosen O, Feldberg L, Gura S, Zichel R. Improved detection of botulinum type E by rational design of a new peptide substrate for endopeptidase-mass spectrometry assay. Anal Biochem 2014; 456:50-2. [PMID: 24721293 DOI: 10.1016/j.ab.2014.03.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Revised: 03/26/2014] [Accepted: 03/29/2014] [Indexed: 12/01/2022]
Abstract
Botulinum neurotoxins (BoNTs) are the most toxic substances known to humans. Endopeptidase-mass spectrometry (Endopep-MS) is used as a specific and rapid in vitro assay to detect BoNTs. In this assay, immunocaptured toxin cleaves a serotype-specific peptide substrate, and the cleavage products are then detected by MS. To further improve the sensitivity of the assay, we report here the rational design of a new substrate peptide for the detection of botulinum neurotoxin type E (BoNT/E). Our strategy was based on previously reported structural interactions integrated with analysis method efficiency considerations. Integration of the newly designed substrate has led to a more than one order of magnitude increased sensitivity of the assay.
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Affiliation(s)
- Osnat Rosen
- Department of Biotechnology, Israel Institute for Biological Research, Ness Ziona 7410001, Israel
| | - Liron Feldberg
- Department of Analytical Chemistry, Israel Institute for Biological Research, Ness Ziona 7410001, Israel
| | - Sigalit Gura
- Department of Analytical Chemistry, Israel Institute for Biological Research, Ness Ziona 7410001, Israel
| | - Ran Zichel
- Department of Biotechnology, Israel Institute for Biological Research, Ness Ziona 7410001, Israel.
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