1
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Leka O, Wu Y, Zanetti G, Furler S, Reinberg T, Marinho J, Schaefer JV, Plückthun A, Li X, Pirazzini M, Kammerer RA. A DARPin promotes faster onset of botulinum neurotoxin A1 action. Nat Commun 2023; 14:8317. [PMID: 38110403 PMCID: PMC10728214 DOI: 10.1038/s41467-023-44102-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 11/30/2023] [Indexed: 12/20/2023] Open
Abstract
In this study, we characterize Designed Ankyrin Repeat Proteins (DARPins) as investigative tools to probe botulinum neurotoxin A1 (BoNT/A1) structure and function. We identify DARPin-F5 that completely blocks SNAP25 substrate cleavage by BoNT/A1 in vitro. X-ray crystallography reveals that DARPin-F5 inhibits BoNT/A1 activity by interacting with a substrate-binding region between the α- and β-exosite. This DARPin does not block substrate cleavage of BoNT/A3, indicating that DARPin-F5 is a subtype-specific inhibitor. BoNT/A1 Glu-171 plays a critical role in the interaction with DARPin-F5 and its mutation to Asp, the residue found in BoNT/A3, results in a loss of inhibition of substrate cleavage. In contrast to the in vitro results, DARPin-F5 promotes faster substrate cleavage of BoNT/A1 in primary neurons and muscle tissue by increasing toxin translocation. Our findings could have important implications for the application of BoNT/A1 in therapeutic areas requiring faster onset of toxin action combined with long persistence.
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Affiliation(s)
- Oneda Leka
- Laboratory of Biomolecular Research, Division of Biology, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - Yufan Wu
- Laboratory of Biomolecular Research, Division of Biology, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - Giulia Zanetti
- Department of Biomedical Sciences, University of Padova, 35121, Padova, Italy
| | - Sven Furler
- Department of Biochemistry, University of Zurich, 8057, Zurich, Switzerland
| | - Thomas Reinberg
- Department of Biochemistry, University of Zurich, 8057, Zurich, Switzerland
| | - Joana Marinho
- Department of Biochemistry, University of Zurich, 8057, Zurich, Switzerland
| | - Jonas V Schaefer
- Department of Biochemistry, University of Zurich, 8057, Zurich, Switzerland
| | - Andreas Plückthun
- Department of Biochemistry, University of Zurich, 8057, Zurich, Switzerland
| | - Xiaodan Li
- Laboratory of Biomolecular Research, Division of Biology, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - Marco Pirazzini
- Department of Biomedical Sciences, University of Padova, 35121, Padova, Italy
| | - Richard A Kammerer
- Laboratory of Biomolecular Research, Division of Biology, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland.
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2
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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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3
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Dyer RP, Isoda HM, Salcedo GS, Speciale G, Fletcher MH, Le LQ, Liu Y, Brami-Cherrier K, Malik SZ, Vazquez-Cintron EJ, Chu AC, Rupp DC, Jacky BPS, Nguyen TTM, Katz BB, Steward LE, Majumdar S, Brideau-Andersen AD, Weiss GA. Reengineering the specificity of the highly selective Clostridium botulinum protease via directed evolution. Sci Rep 2022; 12:9956. [PMID: 35705606 PMCID: PMC9200782 DOI: 10.1038/s41598-022-13617-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 05/17/2022] [Indexed: 11/10/2022] Open
Abstract
The botulinum neurotoxin serotype A (BoNT/A) cuts a single peptide bond in SNAP25, an activity used to treat a wide range of diseases. Reengineering the substrate specificity of BoNT/A’s protease domain (LC/A) could expand its therapeutic applications; however, LC/A’s extended substrate recognition (≈ 60 residues) challenges conventional approaches. We report a directed evolution method for retargeting LC/A and retaining its exquisite specificity. The resultant eight-mutation LC/A (omLC/A) has improved cleavage specificity and catalytic efficiency (1300- and 120-fold, respectively) for SNAP23 versus SNAP25 compared to a previously reported LC/A variant. Importantly, the BoNT/A holotoxin equipped with omLC/A retains its ability to form full-length holotoxin, infiltrate neurons, and cleave SNAP23. The identification of substrate control loops outside BoNT/A’s active site could guide the design of improved BoNT proteases and inhibitors.
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Affiliation(s)
- Rebekah P Dyer
- Molecular Biology and Biochemistry, University of California, Irvine, 1102 NS-2, Irvine, CA, 92697-2025, USA
| | - Hariny M Isoda
- Departments of Chemistry, University of California, Irvine, 1102 NS-2, Irvine, CA, 92697-2025, USA
| | - Gabriela S Salcedo
- Molecular Biology and Biochemistry, University of California, Irvine, 1102 NS-2, Irvine, CA, 92697-2025, USA
| | - Gaetano Speciale
- Departments of Chemistry, University of California, Irvine, 1102 NS-2, Irvine, CA, 92697-2025, USA
| | - Madison H Fletcher
- Departments of Chemistry, University of California, Irvine, 1102 NS-2, Irvine, CA, 92697-2025, USA
| | - Linh Q Le
- Allergan Aesthetics, An AbbVie company, 2525 Dupont Drive, Irvine, CA, 92612, USA
| | - Yi Liu
- Allergan Aesthetics, An AbbVie company, 2525 Dupont Drive, Irvine, CA, 92612, USA
| | - Karen Brami-Cherrier
- Allergan Aesthetics, An AbbVie company, 2525 Dupont Drive, Irvine, CA, 92612, USA
| | - Shiazah Z Malik
- Allergan Aesthetics, An AbbVie company, 2525 Dupont Drive, Irvine, CA, 92612, USA
| | | | - Andrew C Chu
- Molecular Biology and Biochemistry, University of California, Irvine, 1102 NS-2, Irvine, CA, 92697-2025, USA
| | - David C Rupp
- Allergan Aesthetics, An AbbVie company, 2525 Dupont Drive, Irvine, CA, 92612, USA
| | - Birgitte P S Jacky
- Allergan Aesthetics, An AbbVie company, 2525 Dupont Drive, Irvine, CA, 92612, USA
| | - Thu T M Nguyen
- Departments of Chemistry, University of California, Irvine, 1102 NS-2, Irvine, CA, 92697-2025, USA
| | - Benjamin B Katz
- Departments of Chemistry, University of California, Irvine, 1102 NS-2, Irvine, CA, 92697-2025, USA
| | - Lance E Steward
- Allergan Aesthetics, An AbbVie company, 2525 Dupont Drive, Irvine, CA, 92612, USA
| | - Sudipta Majumdar
- Departments of Chemistry, University of California, Irvine, 1102 NS-2, Irvine, CA, 92697-2025, USA
| | | | - Gregory A Weiss
- Departments of Chemistry, University of California, Irvine, 1102 NS-2, Irvine, CA, 92697-2025, USA. .,Molecular Biology and Biochemistry, University of California, Irvine, 1102 NS-2, Irvine, CA, 92697-2025, USA. .,Pharmaceutical Sciences, University of California, Irvine, 1102 NS-2, Irvine, CA, 92697-2025, USA.
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4
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Lam KH, Tremblay JM, Perry K, Ichtchenko K, Shoemaker CB, Jin R. Probing the structure and function of the protease domain of botulinum neurotoxins using single-domain antibodies. PLoS Pathog 2022; 18:e1010169. [PMID: 34990480 PMCID: PMC8769338 DOI: 10.1371/journal.ppat.1010169] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 01/19/2022] [Accepted: 12/04/2021] [Indexed: 12/03/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are among the deadliest of bacterial toxins. BoNT serotype A and B in particular pose the most serious threat to humans because of their high potency and persistence. To date, there is no effective treatment for late post-exposure therapy of botulism patients. Here, we aim to develop single-domain variable heavy-chain (VHH) antibodies targeting the protease domains (also known as the light chain, LC) of BoNT/A and BoNT/B as antidotes for post-intoxication treatments. Using a combination of X-ray crystallography and biochemical assays, we investigated the structures and inhibition mechanisms of a dozen unique VHHs that recognize four and three non-overlapping epitopes on the LC of BoNT/A and BoNT/B, respectively. We show that the VHHs that inhibit the LC activity occupy the extended substrate-recognition exosites or the cleavage pocket of LC/A or LC/B and thus block substrate binding. Notably, we identified several VHHs that recognize highly conserved epitopes across BoNT/A or BoNT/B subtypes, suggesting that these VHHs exhibit broad subtype efficacy. Further, we identify two novel conformations of the full-length LC/A, that could aid future development of inhibitors against BoNT/A. Our studies lay the foundation for structure-based engineering of protein- or peptide-based BoNT inhibitors with enhanced potencies and cross-subtypes properties.
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Affiliation(s)
- Kwok-ho Lam
- Department of Physiology and Biophysics, University of California, Irvine, California, United States of America
| | - Jacqueline M. Tremblay
- Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts, United States of America
| | - Kay Perry
- NE-CAT, Department of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Argonne, Illinois, United States of America
| | - Konstantin Ichtchenko
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, New York, United States of America
| | - Charles B. Shoemaker
- Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts, United States of America
| | - Rongsheng Jin
- Department of Physiology and Biophysics, University of California, Irvine, California, United States of America
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5
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Cai S, Kumar R, Singh BR. Clostridial Neurotoxins: Structure, Function and Implications to Other Bacterial Toxins. Microorganisms 2021; 9:2206. [PMID: 34835332 PMCID: PMC8618262 DOI: 10.3390/microorganisms9112206] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/19/2021] [Accepted: 10/19/2021] [Indexed: 01/20/2023] Open
Abstract
Gram-positive bacteria are ancient organisms. Many bacteria, including Gram-positive bacteria, produce toxins to manipulate the host, leading to various diseases. While the targets of Gram-positive bacterial toxins are diverse, many of those toxins use a similar mechanism to invade host cells and exert their functions. Clostridial neurotoxins produced by Clostridial tetani and Clostridial botulinum provide a classical example to illustrate the structure-function relationship of bacterial toxins. Here, we critically review the recent progress of the structure-function relationship of clostridial neurotoxins, including the diversity of the clostridial neurotoxins, the mode of actions, and the flexible structures required for the activation of toxins. The mechanism clostridial neurotoxins use for triggering their activity is shared with many other Gram-positive bacterial toxins, especially molten globule-type structures. This review also summarizes the implications of the molten globule-type flexible structures to other Gram-positive bacterial toxins. Understanding these highly dynamic flexible structures in solution and their role in the function of bacterial toxins not only fills in the missing link of the high-resolution structures from X-ray crystallography but also provides vital information for better designing antidotes against those toxins.
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Affiliation(s)
- Shuowei Cai
- Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, Dartmouth, MA 02747, USA
| | - Raj Kumar
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA; (R.K.); (B.R.S.)
| | - Bal Ram Singh
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA; (R.K.); (B.R.S.)
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6
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Shropshire JD, Rosenberg R, Bordenstein SR. The impacts of cytoplasmic incompatibility factor (cifA and cifB) genetic variation on phenotypes. Genetics 2021; 217:1-13. [PMID: 33683351 PMCID: PMC8218869 DOI: 10.1093/genetics/iyaa007] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 11/13/2020] [Indexed: 11/13/2022] Open
Abstract
Wolbachia are maternally transmitted, intracellular bacteria that can
often selfishly spread through arthropod populations via cytoplasmic incompatibility (CI).
CI manifests as embryonic death when males expressing prophage WO genes
cifA and cifB mate with uninfected females or females
harboring an incompatible Wolbachia strain. Females with a compatible
cifA-expressing strain rescue CI. Thus, cif-mediated
CI confers a relative fitness advantage to females transmitting
Wolbachia. However, whether cif sequence variation
underpins incompatibilities between Wolbachia strains and variation in CI
penetrance remains unknown. Here, we engineer Drosophila melanogaster to
transgenically express cognate and non-cognate cif homologs and assess
their CI and rescue capability. Cognate expression revealed that cifA;B
native to D. melanogaster causes strong CI, and cognate
cifA;B homologs from two other Drosophila-associated
Wolbachia cause weak transgenic CI, including the first demonstration
of phylogenetic type 2 cifA;B CI. Intriguingly, non-cognate expression of
cifA and cifB alleles from different strains revealed
that cifA homologs generally contribute to strong transgenic CI and
interchangeable rescue despite their evolutionary divergence, and cifB
genetic divergence contributes to weak or no transgenic CI. Finally, we find that a type 1
cifA can rescue CI caused by a genetically divergent type 2
cifA;B in a manner consistent with unidirectional incompatibility. By
genetically dissecting individual CI functions for type 1 and 2 cifA and
cifB, this work illuminates new relationships between
cif genotype and CI phenotype. We discuss the relevance of these
findings to CI’s genetic basis, phenotypic variation patterns, and mechanism.
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Affiliation(s)
- J Dylan Shropshire
- Department of Biological Sciences, Vanderbilt University, VU Station B, Box 35-1634, Nashville, TN 37235, USA.,Vanderbilt Microbiome Initiative, Vanderbilt University, VU Station B, Box 35-1634, Nashville, TN 37235, USA.,Division of Biological Sciences, University of Montana, 32 Campus Drive, Missoula, MT 59812, USA
| | - Rachel Rosenberg
- Department of Biological Sciences, Vanderbilt University, VU Station B, Box 35-1634, Nashville, TN 37235, USA.,Vanderbilt Microbiome Initiative, Vanderbilt University, VU Station B, Box 35-1634, Nashville, TN 37235, USA
| | - Seth R Bordenstein
- Department of Biological Sciences, Vanderbilt University, VU Station B, Box 35-1634, Nashville, TN 37235, USA.,Vanderbilt Microbiome Initiative, Vanderbilt University, VU Station B, Box 35-1634, Nashville, TN 37235, USA.,Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN 37235, USA.,Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN 37235, USA
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7
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Kumar R, Maksudov F, Kononova O, Marx KA, Barsegov V, Singh BR. Botulinum Endopeptidase: SAXS Experiments and MD Simulations Reveal Extended Solution Structures That Account for Its Biochemical Properties. J Phys Chem B 2020; 124:5801-5812. [PMID: 32543194 DOI: 10.1021/acs.jpcb.0c02817] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Development of antidotes against botulism requires understanding of the enzymatically active conformations of Botulinum neurotoxin serotype A (BoNT/A) light chain (LCA). We performed small angle X-ray scattering (SAXS) to characterize the solution structures of truncated light chain (tLCA). The 34-37 Å radius of gyration of tLCA was 1.5-times greater than the averaged 22-23-Å radius from the crystal structures. The bimodal distribution of interatomic distances P(r) indicated the two-domain tLCA structure with 129-133 Å size, and Kratky plots indicated the tLCA partial unfolding in the 25-37 °C temperature range. To interpret these data, we employed molecular dynamics simulations and machine learning. Excellent agreement between experimental and theoretical P(r) profiles helped to resolve conformational subpopulations of tLCA in solution. Partial unfolding of the C-terminal portion of tLCA (residues 339-425) results in formation of extended conformations with the larger globular domain (residues 2-298) and the smaller unstructured domain (339-425). The catalytic domain, buried 20 Å-deep inside the crystal structure, becomes accessible in extended solution conformations (8-9 Å deep). The C- and N-termini containing different functional sequence motifs are maximally separated in the extended conformations. Our results offer physical insights into the molecular basis of BoNT/A function and stress the importance of reversible unfolding-refolding transitions and hydrophobic interactions.
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Affiliation(s)
- Raj Kumar
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, Massachusetts 02747, United States
| | - Farkhad Maksudov
- Department of Chemistry, University of Massachusetts, Lowell, Massachusetts 01854, United States
| | - Olga Kononova
- Department of Chemistry, University of Massachusetts, Lowell, Massachusetts 01854, United States
| | - Kenneth A Marx
- Department of Chemistry, University of Massachusetts, Lowell, Massachusetts 01854, United States
| | - Valeri Barsegov
- Department of Chemistry, University of Massachusetts, Lowell, Massachusetts 01854, United States
| | - Bal Ram Singh
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, Massachusetts 02747, United States
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8
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Bioinformatic discovery of a toxin family in Chryseobacterium piperi with sequence similarity to botulinum neurotoxins. Sci Rep 2019; 9:1634. [PMID: 30733520 PMCID: PMC6367388 DOI: 10.1038/s41598-018-37647-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 12/05/2018] [Indexed: 11/12/2022] Open
Abstract
Clostridial neurotoxins (CNTs), which include botulinum neurotoxins (BoNTs) and tetanus neurotoxin (TeNT), are the most potent toxins known to science and are the causative agents of botulism and tetanus, respectively. The evolutionary origins of CNTs and their relationships to other proteins remains an intriguing question. Here we present a large-scale bioinformatic screen for putative toxin genes in all currently available genomes. We detect a total of 311 protein sequences displaying at least partial homology to BoNTs, including 161 predicted toxin sequences that have never been characterized. We focus on a novel toxin family from Chryseobacterium piperi with homology to BoNTs. We resequenced the genome of C. piperi to confirm and further analyze the genomic context of these toxins, and also examined their potential toxicity by expression of the protease domain of one C. piperi toxin in human cells. Our analysis suggests that these C. piperi sequences encode a novel family of metalloprotease toxins that are distantly related to BoNTs with similar domain architecture. These toxins target a yet unknown class of substrates, potentially reflecting divergence in substrate specificity between the metalloprotease domains of these toxins and the related metalloprotease domain of clostridial neurotoxins.
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9
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Feltrup TM, Patel K, Kumar R, Cai S, Singh BR. A novel role of C-terminus in introducing a functionally flexible structure critical for the biological activity of botulinum neurotoxin. Sci Rep 2018; 8:8884. [PMID: 29891845 PMCID: PMC5995822 DOI: 10.1038/s41598-018-26764-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 05/17/2018] [Indexed: 02/06/2023] Open
Abstract
Botulinum neurotoxin (BoNT) is responsible for botulism, a clinical condition resulting in flaccid muscle paralysis and potentially death. The light chain is responsible for its intracellular toxicity through its endopeptidase activity. Available crystal structures of BoNT/A light chains (LCA) are based on various truncated versions (tLCA) of the full-length LCA (fLCA) and do not necessarily reflect the true structure of LCA in solution. The understanding of the mechanism of action, longevity of intoxication, and an improved development of endopeptidase inhibitors are dependent on first having a better insight into the structure of LCA in solution. Using an array of biophysical techniques, we report that the fLCA structure is significantly more flexible than tLCA in solution, which may be responsible for its dramatically higher enzymatic activity. This seems to be achieved by a much stronger, more rapid binding to substrate (SNAP-25) of the fLCA compared to tLCA. These results suggest that the C-terminus of LCA plays a critical role in introducing a flexible structure, which is essential for its biological function. This is the first report of such a massive structural role of the C-terminus of a protein being critical for maintaining a functional state.
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Affiliation(s)
- Thomas M Feltrup
- Department of Chemistry & Biochemistry, University of Massachusetts Dartmouth, North Dartmouth, MA, 02747, USA
| | - Kruti Patel
- Department of Chemistry & Biochemistry, University of Massachusetts Dartmouth, North Dartmouth, MA, 02747, USA
| | - Raj Kumar
- Botulinum Research Center, Institute of Advanced Sciences, North Dartmouth, MA, 02747, USA
| | - Shuowei Cai
- Department of Chemistry & Biochemistry, University of Massachusetts Dartmouth, North Dartmouth, MA, 02747, USA
| | - Bal Ram Singh
- Botulinum Research Center, Institute of Advanced Sciences, North Dartmouth, MA, 02747, USA.
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10
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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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11
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Ambrin G, Kumar R, Singh BR. Differential endopeptidase activity of different forms of type A botulinum neurotoxin: A unique relationship between the size of the substrate and activity of the enzyme. Toxicon 2018; 144:34-41. [PMID: 29309744 DOI: 10.1016/j.toxicon.2017.12.055] [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: 08/17/2017] [Revised: 12/27/2017] [Accepted: 12/30/2017] [Indexed: 10/18/2022]
Abstract
Botulinum neurotoxins (BoNTs; serotypes A-G) are metalloproteases, which cleave and inactivate cellular proteins essential for neurotransmitter release. In bacterial cultures, BoNTs are secreted as a complex of the neurotoxin and a group of neurotoxin associated proteins (NAPs). Under physiological condition (pH 7.4), this complex is believed to be dissociated to separate the neurotoxin from NAPs. BoNT consists of a 50 kDa light (L) chain (LC or catalytic domain) and a 100 kDa heavy (H) chain (or HC) linked through a disulfide bond and other non-covalent interactions. The cell intoxication involves three major steps; binding, membrane translocation and inhibition of neurotransmitter release. The last step of intoxication, endopeptidase activity, is very unique and specific that can be used for detection of the complex and isolated forms of the toxin. A fluorescent tag-labeled synthetic peptide (SNAPtide) derived from a segment of SNAP-25, an intracellular substrate of BoNT/A, is used to detect and assay the endopeptidase activity of BoNT/A. The detection of the signal is based on the change in the fluorescence energy transfer after selective cleavage of the peptide by the BoNT/A. In this report, we demonstrate that SNAPtide as a commonly used substrate widely differ in reaction with BoNT/A complex, BoNT/A, and BoNT/A light chain. These findings have implications for assays used in detection, and in screening potential inhibitors.
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Affiliation(s)
- Ghuncha Ambrin
- Department of Chemistry and Biochemistry, University of Massachusetts, North Dartmouth, MA, 02747, USA
| | - Raj Kumar
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA
| | - Bal Ram Singh
- Department of Chemistry and Biochemistry, University of Massachusetts, North Dartmouth, MA, 02747, USA; Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA.
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12
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Scheps D, López de la Paz M, Jurk M, Hofmann F, Frevert J. Design of modified botulinum neurotoxin A1 variants with a shorter persistence of paralysis and duration of action. Toxicon 2017; 139:101-108. [PMID: 28918229 DOI: 10.1016/j.toxicon.2017.09.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 08/24/2017] [Accepted: 09/09/2017] [Indexed: 01/08/2023]
Abstract
Botulinum neurotoxins (BoNTs) are classified by their antigenic properties into seven serotypes (A-G) and in addition by their corresponding subtypes. They are further characterized by divergent onset and duration of effect. Injections of low doses of botulinum neurotoxins cause localized muscle paralysis that is beneficial for the treatment of several medical disorders and aesthetic indications. Optimizing the therapeutic properties could offer new treatment opportunities. This report describes a rational design approach to modify the pharmacological properties by mutations in the C-terminus of BoNT/A1 light chain (LC). Toxins with C-terminal modified LC's displayed an altered onset and duration of the paralytic effect in vivo. The level of effect was dependent on the kind of the mutation in the sequence of the C-terminus. A mutant with three mutations (T420E F423M Y426F) revealed a faster onset and a shorter duration than BoNT/A1 wild type (WT). It could be shown that the C-terminus of BoNT/A1-Lc controls both onset and duration of effect. Thus, it is possible to create a mutated BoNT/A1 with different pharmacological properties which might be useful in the therapy of new indications. This strategy opens the way to design BoNT variants with novel and useful properties.
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Affiliation(s)
- Daniel Scheps
- Merz Pharmaceuticals GmbH, Hermannswerder Haus 15, 14473, Potsdam, Germany
| | | | - Marcel Jurk
- Merz Pharmaceuticals GmbH, Hermannswerder Haus 15, 14473, Potsdam, Germany
| | - Fred Hofmann
- Merz Pharmaceuticals GmbH, Hermannswerder Haus 15, 14473, Potsdam, Germany
| | - Jürgen Frevert
- Merz Pharmaceuticals GmbH, Hermannswerder Haus 15, 14473, Potsdam, Germany.
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13
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Jacobson AR, Adler M, Silvaggi NR, Allen KN, Smith GM, Fredenburg RA, Stein RL, Park JB, Feng X, Shoemaker CB, Deshpande SS, Goodnough MC, Malizio CJ, Johnson EA, Pellett S, Tepp WH, Tzipori S. Small molecule metalloprotease inhibitor with in vitro, ex vivo and in vivo efficacy against botulinum neurotoxin serotype A. Toxicon 2017; 137:36-47. [PMID: 28698055 DOI: 10.1016/j.toxicon.2017.06.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 06/28/2017] [Accepted: 06/29/2017] [Indexed: 01/08/2023]
Abstract
Botulinum neurotoxins (BoNTs) are the most toxic substances known to mankind and are the causative agents of the neuroparalytic disease botulism. Their ease of production and extreme toxicity have caused these neurotoxins to be classified as Tier 1 bioterrorist threat agents and have led to a sustained effort to develop countermeasures to treat intoxication in case of a bioterrorist attack. While timely administration of an approved antitoxin is effective in reducing the severity of botulism, reversing intoxication requires different strategies. In the present study, we evaluated ABS 252 and other mercaptoacetamide small molecule active-site inhibitors of BoNT/A light chain using an integrated multi-assay approach. ABS 252 showed inhibitory activity in enzymatic, cell-based and muscle activity assays, and importantly, produced a marked delay in time-to-death in mice. The results suggest that a multi-assay approach is an effective strategy for discovery of potential BoNT therapeutic candidates.
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Affiliation(s)
| | - Michael Adler
- Neuroscience Branch, Medical Toxicology Division, USAMRICD, APG, MD, 21010, United States.
| | - Nicholas R Silvaggi
- Department of Chemistry, Boston University, Boston, MA, 02215, United States
| | - Karen N Allen
- Department of Chemistry, Boston University, Boston, MA, 02215, United States
| | | | - Ross A Fredenburg
- Center for Neurologic Diseases, Brigham & Women's Hospital and Harvard Medical School, Cambridge, MA, 02139, United States
| | - Ross L Stein
- Laboratory for Drug Discovery in Neurodegeneration, Brigham & Women's Hospital and Harvard Medical School, Cambridge, MA, 02139, United States
| | - Jong-Beak Park
- Division of Infectious Diseases, Tufts University Cummings School of Veterinary Medicine, North Grafton, MA, 01536, United States
| | - Xiaochuan Feng
- Division of Infectious Diseases, Tufts University Cummings School of Veterinary Medicine, North Grafton, MA, 01536, United States
| | - Charles B Shoemaker
- Division of Infectious Diseases, Tufts University Cummings School of Veterinary Medicine, North Grafton, MA, 01536, United States
| | - Sharad S Deshpande
- Neuroscience Branch, Medical Toxicology Division, USAMRICD, APG, MD, 21010, United States
| | | | | | - Eric A Johnson
- Department of Bacteriology, University of Wisconsin at Madison, Madison, WI, 53706, United States
| | - Sabine Pellett
- Department of Bacteriology, University of Wisconsin at Madison, Madison, WI, 53706, United States
| | - William H Tepp
- Department of Bacteriology, University of Wisconsin at Madison, Madison, WI, 53706, United States
| | - Saul Tzipori
- Division of Infectious Diseases, Tufts University Cummings School of Veterinary Medicine, North Grafton, MA, 01536, United States
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14
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Huang J, Wu C, Liu D, Yang X, Wu R, Zhang J, Ma C, He H. C-terminal domains of bacterial proteases: structure, function and the biotechnological applications. J Appl Microbiol 2016; 122:12-22. [DOI: 10.1111/jam.13317] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 09/21/2016] [Accepted: 10/03/2016] [Indexed: 12/28/2022]
Affiliation(s)
- J. Huang
- State Key Laboratory of Medical Genetics; School of Life Sciences; Central South University; Changsha China
| | - C. Wu
- State Key Laboratory of Medical Genetics; School of Life Sciences; Central South University; Changsha China
| | - D. Liu
- State Key Laboratory of Medical Genetics; School of Life Sciences; Central South University; Changsha China
| | - X. Yang
- State Key Laboratory of Medical Genetics; School of Life Sciences; Central South University; Changsha China
| | - R. Wu
- State Key Laboratory of Medical Genetics; School of Life Sciences; Central South University; Changsha China
| | - J. Zhang
- State Key Laboratory of Medical Genetics; School of Life Sciences; Central South University; Changsha China
| | - C. Ma
- State Key Laboratory of Medical Genetics; School of Life Sciences; Central South University; Changsha China
| | - H. He
- State Key Laboratory of Medical Genetics; School of Life Sciences; Central South University; Changsha China
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15
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Bompiani KM, Caglič D, Krutein MC, Benoni G, Hrones M, Lairson LL, Bian H, Smith GR, Dickerson TJ. High-Throughput Screening Uncovers Novel Botulinum Neurotoxin Inhibitor Chemotypes. ACS COMBINATORIAL SCIENCE 2016; 18:461-74. [PMID: 27314875 DOI: 10.1021/acscombsci.6b00033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Botulism is caused by potent and specific bacterial neurotoxins that infect host neurons and block neurotransmitter release. Treatment for botulism is limited to administration of an antitoxin within a short time window, before the toxin enters neurons. Alternatively, current botulism drug development targets the toxin light chain, which is a zinc-dependent metalloprotease that is delivered into neurons and mediates long-term pathology. Several groups have identified inhibitory small molecules, peptides, or aptamers, although no molecule has advanced to the clinic due to a lack of efficacy in advanced models. Here we used a homogeneous high-throughput enzyme assay to screen three libraries of drug-like small molecules for new chemotypes that modulate recombinant botulinum neurotoxin light chain activity. High-throughput screening of 97088 compounds identified numerous small molecules that activate or inhibit metalloprotease activity. We describe four major classes of inhibitory compounds identified, detail their structure-activity relationships, and assess their relative inhibitory potency. A previously unreported chemotype in any context of enzyme inhibition is described with potent submicromolar inhibition (Ki = 200-300 nM). Additional detailed kinetic analyses and cellular cytotoxicity assays indicate the best compound from this series is a competitive inhibitor with cytotoxicity values around 4-5 μM. Given the potency and drug-like character of these lead compounds, further studies, including cellular activity assays and DMPK analysis, are justified.
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Affiliation(s)
- Kristin M. Bompiani
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Dejan Caglič
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Michelle C. Krutein
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Galit Benoni
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Morgan Hrones
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Luke L. Lairson
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Haiyan Bian
- Fox Chase Chemical Diversity Center, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
| | - Garry R. Smith
- Fox Chase Chemical Diversity Center, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
| | - Tobin J. Dickerson
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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16
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Montgomery VA, Ahmed SA, Olson MA, Mizanur RM, Stafford RG, Roxas-Duncan VI, Smith LA. Ex vivo inhibition of Clostridium botulinum neurotoxin types B, C, E, and F by small molecular weight inhibitors. Toxicon 2015; 98:12-9. [PMID: 25707753 DOI: 10.1016/j.toxicon.2015.02.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 02/06/2015] [Accepted: 02/19/2015] [Indexed: 11/28/2022]
Abstract
Two small molecular weight inhibitors, compounds CB7969312 and CB7967495, that displayed inhibition of botulinum neurotoxin serotype A in a previous study, were evaluated for inhibition of botulinum neurotoxin serotypes B, C, E, and F. The small molecular weight inhibitors were assessed by molecular modeling, UPLC-based peptide cleavage assay; and an ex vivo assay, the mouse phrenic nerve - hemidiaphragm assay (MPNHDA). While both compounds were inhibitors of botulinum neurotoxin (BoNT) serotypes B, C, and F in the MPNHDA, compound CB7969312 was effective at lower molar concentrations than compound CB7967495. However, compound CB7967495 was significantly more effective at preventing BoNTE intoxication than compound CB7969312. In the UPLC-based peptide cleavage assay, CB7969312 was also more effective against LcC. Both compounds inhibited BoNTE, but not BoNTF, LcE, or LcF in the UPLC-based peptide cleavage assay. Molecular modeling studies predicted that both compounds would be effective inhibitors of BoNTs B, C, E, and F. But CB7967495 was predicted to be a more effective inhibitor of the four serotypes (B, C, E, and F) than CB7969312. This is the first report of a small molecular weight compound that inhibits serotypes B, C, E, and F in the ex vivo assay.
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Affiliation(s)
- Vicki A Montgomery
- U.S. Army Medical Research Institute of Infectious Diseases, Division of Molecular and Translational Sciences, 1425 Porter St. Ft Detrick, Frederick, MD, USA.
| | - S Ashraf Ahmed
- U.S. Army Medical Research Institute of Infectious Diseases, Division of Molecular and Translational Sciences, 1425 Porter St. Ft Detrick, Frederick, MD, USA.
| | - Mark A Olson
- U.S. Army Medical Research Institute of Infectious Diseases, Division of Molecular and Translational Sciences, 1425 Porter St. Ft Detrick, Frederick, MD, USA.
| | - Rahman M Mizanur
- U.S. Army Medical Research Institute of Infectious Diseases, Biosurety Division, 1430 Veterans Dr, Ft Detrick, Frederick, MD, USA(1).
| | - Robert G Stafford
- U.S. Army Medical Research Institute of Infectious Diseases, Division of Molecular and Translational Sciences, 1425 Porter St. Ft Detrick, Frederick, MD, USA.
| | - Virginia I Roxas-Duncan
- U.S. Army Medical Research Institute of Infectious Diseases, Biosurety Division, 1430 Veterans Dr, Ft Detrick, Frederick, MD, USA(1).
| | - Leonard A Smith
- Medical Countermeasures Technology, U.S. Army Medical Research and Material Command, 1425 Porter St. Ft Detrick, Frederick, MD, USA.
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17
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Johnson CN, Berdini V, Beke L, Bonnet P, Brehmer D, Coyle JE, Day PJ, Frederickson M, Freyne EJE, Gilissen RAHJ, Hamlett CCF, Howard S, Meerpoel L, McMenamin R, Patel S, Rees DC, Sharff A, Sommen F, Wu T, Linders JTM. Fragment-based discovery of type I inhibitors of maternal embryonic leucine zipper kinase. ACS Med Chem Lett 2015; 6:25-30. [PMID: 25589925 DOI: 10.1021/ml5001245] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 05/15/2014] [Indexed: 11/30/2022] Open
Abstract
Fragment-based drug design was successfully applied to maternal embryonic leucine zipper kinase (MELK). A low affinity (160 μM) fragment hit was identified, which bound to the hinge region with an atypical binding mode, and this was optimized using structure-based design into a low-nanomolar and cell-penetrant inhibitor, with a good selectivity profile, suitable for use as a chemical probe for elucidation of MELK biology.
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Affiliation(s)
- Christopher N. Johnson
- Astex Pharmaceuticals, 436
Cambridge Science Park, Milton Road, Cambridge CB4 0QA, United Kingdom
| | - Valerio Berdini
- Astex Pharmaceuticals, 436
Cambridge Science Park, Milton Road, Cambridge CB4 0QA, United Kingdom
| | - Lijs Beke
- Janssen Research and Development, A Division of Janssen Pharmaceutica N.V., Turnhoutseweg 30, Beerse 2340 Belgium
| | - Pascal Bonnet
- Janssen Research and Development, A Division of Janssen Pharmaceutica N.V., Turnhoutseweg 30, Beerse 2340 Belgium
| | - Dirk Brehmer
- Janssen Research and Development, A Division of Janssen Pharmaceutica N.V., Turnhoutseweg 30, Beerse 2340 Belgium
| | - Joseph E. Coyle
- Astex Pharmaceuticals, 436
Cambridge Science Park, Milton Road, Cambridge CB4 0QA, United Kingdom
| | - Phillip J. Day
- Astex Pharmaceuticals, 436
Cambridge Science Park, Milton Road, Cambridge CB4 0QA, United Kingdom
| | - Martyn Frederickson
- Astex Pharmaceuticals, 436
Cambridge Science Park, Milton Road, Cambridge CB4 0QA, United Kingdom
| | - Eddy J. E. Freyne
- Janssen Research and Development, A Division of Janssen Pharmaceutica N.V., Turnhoutseweg 30, Beerse 2340 Belgium
| | - Ron A. H. J. Gilissen
- Janssen Research and Development, A Division of Janssen Pharmaceutica N.V., Turnhoutseweg 30, Beerse 2340 Belgium
| | | | - Steven Howard
- Astex Pharmaceuticals, 436
Cambridge Science Park, Milton Road, Cambridge CB4 0QA, United Kingdom
| | - Lieven Meerpoel
- Janssen Research and Development, A Division of Janssen Pharmaceutica N.V., Turnhoutseweg 30, Beerse 2340 Belgium
| | - Rachel McMenamin
- Astex Pharmaceuticals, 436
Cambridge Science Park, Milton Road, Cambridge CB4 0QA, United Kingdom
| | - Sahil Patel
- Astex Pharmaceuticals, 436
Cambridge Science Park, Milton Road, Cambridge CB4 0QA, United Kingdom
| | - David C. Rees
- Astex Pharmaceuticals, 436
Cambridge Science Park, Milton Road, Cambridge CB4 0QA, United Kingdom
| | - Andrew Sharff
- Astex Pharmaceuticals, 436
Cambridge Science Park, Milton Road, Cambridge CB4 0QA, United Kingdom
| | - François Sommen
- Janssen Research and Development, A Division of Janssen Pharmaceutica N.V., Turnhoutseweg 30, Beerse 2340 Belgium
| | - Tongfei Wu
- Janssen Research and Development, A Division of Janssen Pharmaceutica N.V., Turnhoutseweg 30, Beerse 2340 Belgium
| | - Joannes T. M. Linders
- Janssen Research and Development, A Division of Janssen Pharmaceutica N.V., Turnhoutseweg 30, Beerse 2340 Belgium
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18
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Mizanur RM, Stafford RG, Ahmed SA. Cleavage of SNAP25 and its shorter versions by the protease domain of serotype A botulinum neurotoxin. PLoS One 2014; 9:e95188. [PMID: 24769566 PMCID: PMC4000213 DOI: 10.1371/journal.pone.0095188] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 03/25/2014] [Indexed: 11/18/2022] Open
Abstract
Various substrates, catalysts, and assay methods are currently used to screen inhibitors for their effect on the proteolytic activity of botulinum neurotoxin. As a result, significant variation exists in the reported results. Recently, we found that one source of variation was the use of various catalysts, and have therefore evaluated its three forms. In this paper, we characterize three substrates under near uniform reaction conditions using the most active catalytic form of the toxin. Bovine serum albumin at varying optimum concentrations stimulated enzymatic activity with all three substrates. Sodium chloride had a stimulating effect on the full length synaptosomal-associated protein of 25 kDa (SNAP25) and its 66-mer substrates but had an inhibitory effect on the 17-mer substrate. We found that under optimum conditions, full length SNAP25 was a better substrate than its shorter 66-mer or 17-mer forms both in terms of kcat, Km, and catalytic efficiency kcat/Km. Assay times greater than 15 min introduced large variations and significantly reduced the catalytic efficiency. In addition to characterizing the three substrates, our results identify potential sources of variations in previous published results, and underscore the importance of using well-defined reaction components and assay conditions.
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Affiliation(s)
- Rahman M. Mizanur
- Department of Cell Biology and Biochemistry, Molecular and Translational Sciences Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland, United States of America
| | - Robert G. Stafford
- Department of Cell Biology and Biochemistry, Molecular and Translational Sciences Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland, United States of America
| | - S. Ashraf Ahmed
- Department of Cell Biology and Biochemistry, Molecular and Translational Sciences Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland, United States of America
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19
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Patel K, Cai S, Singh BR. Current strategies for designing antidotes against botulinum neurotoxins. Expert Opin Drug Discov 2014; 9:319-33. [DOI: 10.1517/17460441.2014.884066] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Kruti Patel
- University of Massachusetts Dartmouth, Department of Chemistry and Biochemistry, North Dartmouth, MA 02747, USA
| | - Shuowei Cai
- University of Massachusetts Dartmouth, Department of Chemistry and Biochemistry, North Dartmouth, MA 02747, USA
| | - Bal Ram Singh
- University of Massachusetts Dartmouth, Department of Chemistry and Biochemistry, North Dartmouth, MA 02747, USA
- Institute of Advanced Sciences and Prime Bio, Inc., Botulinum Research Center, 166 Chase Road, North Dartmouth, MA 02747, USA
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