1
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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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2
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Sensitive detection of type G botulinum neurotoxin through Endopep-MS peptide substrate optimization. Anal Bioanal Chem 2019; 411:5489-5497. [PMID: 31172236 PMCID: PMC6684539 DOI: 10.1007/s00216-019-01926-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 05/06/2019] [Accepted: 05/16/2019] [Indexed: 11/06/2022]
Abstract
Clostridium botulinum produces botulinum neurotoxins (BoNTs) that are one of the most poisonous substances. In order to respond to public health emergencies, there is a need to develop sensitive and specific methods for detecting botulinum toxin in various clinical matrices. Our laboratory has developed a mass spectrometry-based Endopep-MS assay that is able to rapidly detect and differentiate BoNT serotypes A–G by immunoaffinity capture of toxins and detection of unique cleavage products of peptide substrates. To improve the sensitivity of the Endopep-MS assay for the detection of BoNT serotype G, we report here the optimization of synthetic peptide substrates through systematic substitution, deletion, and incorporation of unnatural amino acids. Our data show that the resulting optimized peptides produced a significant improvement (two orders of magnitude) in assay sensitivity and allowed the detection of 0.01 mouseLD50 toxin present in buffer solution.
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3
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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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4
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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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5
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Bhattacharyya S, Renn JP, Yu H, Marko JF, Matouschek A. An assay for 26S proteasome activity based on fluorescence anisotropy measurements of dye-labeled protein substrates. Anal Biochem 2016; 509:50-59. [PMID: 27296635 DOI: 10.1016/j.ab.2016.05.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 05/13/2016] [Accepted: 05/31/2016] [Indexed: 12/12/2022]
Abstract
The 26S proteasome is the molecular machine at the center of the ubiquitin proteasome system and is responsible for adjusting the concentrations of many cellular proteins. It is a drug target in several human diseases, and assays for the characterization of modulators of its activity are valuable. The 26S proteasome consists of two components: a core particle, which contains the proteolytic sites, and regulatory caps, which contain substrate receptors and substrate processing enzymes, including six ATPases. Current high-throughput assays of proteasome activity use synthetic fluorogenic peptide substrates that report directly on the proteolytic activity of the proteasome, but not on the activities of the proteasome caps that are responsible for protein recognition and unfolding. Here, we describe a simple and robust assay for the activity of the entire 26S proteasome using fluorescence anisotropy to follow the degradation of fluorescently labeled protein substrates. We describe two implementations of the assay in a high-throughput format and show that it meets the expected requirement of ATP hydrolysis and the presence of a canonical degradation signal or degron in the target protein.
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Affiliation(s)
| | - Jonathan P Renn
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Houqing Yu
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA; Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - John F Marko
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA; Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, USA
| | - Andreas Matouschek
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA; Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA.
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6
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Hauser C, Wodtke R, Löser R, Pietsch M. A fluorescence anisotropy-based assay for determining the activity of tissue transglutaminase. Amino Acids 2016; 49:567-583. [PMID: 26886924 DOI: 10.1007/s00726-016-2192-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 02/02/2016] [Indexed: 01/10/2023]
Abstract
Tissue transglutaminase (TGase 2) is the most abundantly expressed enzyme of the transglutaminase family and involved in a large variety of pathological processes, such as neurodegenerative diseases, disorders related to autoimmunity and inflammation as well as tumor growth, progression and metastasis. As a result, TGase 2 represents an attractive target for drug discovery and development, which requires assays that allow for the characterization of modulating agents and are appropriate for high-throughput screening. Herein, we report a fluorescence anisotropy-based approach for the determination of TGase 2's transamidase activity, following the time-dependent increase in fluorescence anisotropy due to the enzyme-catalyzed incorporation of fluorescein- and rhodamine B-conjugated cadaverines 1-3 (acyl acceptor substrates) into N,N-dimethylated casein (acyl donor substrate). These cadaverine derivatives 1-3 were obtained by solid-phase synthesis. To allow efficient conjugation of the rhodamine B moiety, different linkers providing secondary amine functions, such as sarcosyl and isonipecotyl, were introduced between the cadaverine and xanthenyl entities in compounds 2 and 3, respectively, with acyl acceptor 3 showing the most optimal substrate properties of the compounds investigated. The assay was validated for the search of both irreversible and reversible TGase 2 inhibitors using the inactivators iodoacetamide and a recently published L-lysine-derived acrylamide and the allosteric binder GTP, respectively. In addition, the fluorescence anisotropy-based method was proven to be suitable for high-throughput screening (Z' factor of 0.86) and represents a non-radioactive and highly sensitive assay for determining the active TGase 2 concentration.
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Affiliation(s)
- Christoph Hauser
- Center of Pharmacology, Medical Faculty, University of Cologne, Gleueler Str. 24, 50931, Cologne, Germany
| | - Robert Wodtke
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstr. 400, 01328, Dresden, Germany
- Department of Chemistry and Food Chemistry, Technical University Dresden, Mommsenstraße 4, 01062, Dresden, Germany
| | - Reik Löser
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Bautzner Landstr. 400, 01328, Dresden, Germany.
- Department of Chemistry and Food Chemistry, Technical University Dresden, Mommsenstraße 4, 01062, Dresden, Germany.
| | - Markus Pietsch
- Center of Pharmacology, Medical Faculty, University of Cologne, Gleueler Str. 24, 50931, Cologne, Germany.
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7
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An optical biosensor assay for rapid dual detection of Botulinum neurotoxins A and E. Sci Rep 2015; 5:17953. [PMID: 26648139 PMCID: PMC4673697 DOI: 10.1038/srep17953] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 11/02/2015] [Indexed: 12/20/2022] Open
Abstract
The enzymatic activity of the pathogenic botulinum neurotoxins type A and E (BoNT/A and E) leads to potentially lethal paralytic symptoms in humans and their prompt detection is of crucial importance. A chip assay based on Surface Plasmon Resonance monitoring of the cleavage products is a simple method that we have previously established to detect BoNT/A activity. We have now developed a similar format assay to measure BoNT/E activity. A monoclonal antibody specifically recognizing SNAP25 cleaved by BoNT/E was generated and used to measure the appearance of the neo-epitope following injection of BoNT/E over SNAP-25 immobilized on a chip. This assay detects BoNT/E activity at 1 LD50/ml within minutes and linear dose-responses curves were obtained using a multiplexed biosensor. A threshold of 0.01 LD50/ml was achieved after 5 h of cleavage. This assay is 10-fold more sensitive than the in vivo assay for direct detection of BoNT/E in serum samples. The SNAP25 chip assay is able to discriminate in an automated manner the presence of BoNT/E, BoNT/A or a combination of both toxins.
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8
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Shi J, Guo J, Bai G, Chan C, Liu X, Ye W, Hao J, Chen S, Yang M. A graphene oxide based fluorescence resonance energy transfer (FRET) biosensor for ultrasensitive detection of botulinum neurotoxin A (BoNT/A) enzymatic activity. Biosens Bioelectron 2014; 65:238-44. [PMID: 25461164 DOI: 10.1016/j.bios.2014.10.050] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 10/17/2014] [Accepted: 10/20/2014] [Indexed: 11/18/2022]
Abstract
Botulinum neurotoxins (BoNTs) are among the most potent toxic bacterial proteins for humans, which make them potential agents for bioterrorism. Therefore, an ultrasensitive detection of BoNTs and their active states is in great need as field-deployable systems for anti-terrorism applications. We report the construction of a novel graphene oxide (GO)-peptide based fluorescence resonance energy transfer (FRET) biosensor for ultrasensitive detection of the BoNT serotype A light chain (BoNT-LcA) protease activity. A green fluorescence protein (GFP) modified SNAP-25 peptide substrate (SNAP-25-GFP) was optimally designed and synthesized with the centralized recognition/cleavage sites. This FRET platform was constructed by covalent immobilization of peptide substrate on GO with BSA passivation which have advantages of low non-specific adsorption and high stability in protein abundant solution. BoNT-LcA can specifically cleave SNAP-25-GFP substrate covalently immobilized on GO to release the fragment with GFP. Based on fluorescence signal recovery measurement, the target BoNT-LcA was detected sensitively and selectively with the linear detection range from 1fg/mL to 1pg/mL. The limit of detection (LOD) for BoNT-LcA is around 1fg/mL.
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Affiliation(s)
- Jingyu Shi
- Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China
| | - Jiubiao Guo
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, PR China
| | - Gongxun Bai
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, PR China
| | - Chunyu Chan
- Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China
| | - Xuan Liu
- Institute of Textiles & Clothing, The Hong Kong Polytechnic University, Hong Kong, PR China
| | - Weiwei Ye
- Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China
| | - Jianhua Hao
- Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, PR China
| | - Sheng Chen
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, PR China
| | - Mo Yang
- Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, PR China.
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9
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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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10
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Dunning FM, Piazza TM, Zeytin FN, Tucker WC. Isolation and quantification of botulinum neurotoxin from complex matrices using the BoTest matrix assays. J Vis Exp 2014. [PMID: 24638074 DOI: 10.3791/51170] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Accurate detection and quantification of botulinum neurotoxin (BoNT) in complex matrices is required for pharmaceutical, environmental, and food sample testing. Rapid BoNT testing of foodstuffs is needed during outbreak forensics, patient diagnosis, and food safety testing while accurate potency testing is required for BoNT-based drug product manufacturing and patient safety. The widely used mouse bioassay for BoNT testing is highly sensitive but lacks the precision and throughput needed for rapid and routine BoNT testing. Furthermore, the bioassay's use of animals has resulted in calls by drug product regulatory authorities and animal-rights proponents in the US and abroad to replace the mouse bioassay for BoNT testing. Several in vitro replacement assays have been developed that work well with purified BoNT in simple buffers, but most have not been shown to be applicable to testing in highly complex matrices. Here, a protocol for the detection of BoNT in complex matrices using the BoTest Matrix assays is presented. The assay consists of three parts: The first part involves preparation of the samples for testing, the second part is an immunoprecipitation step using anti-BoNT antibody-coated paramagnetic beads to purify BoNT from the matrix, and the third part quantifies the isolated BoNT's proteolytic activity using a fluorogenic reporter. The protocol is written for high throughput testing in 96-well plates using both liquid and solid matrices and requires about 2 hr of manual preparation with total assay times of 4-26 hr depending on the sample type, toxin load, and desired sensitivity. Data are presented for BoNT/A testing with phosphate-buffered saline, a drug product, culture supernatant, 2% milk, and fresh tomatoes and includes discussion of critical parameters for assay success.
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11
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Luo S, Li T, Wang Q, Tian R, Liu H, Fang H, Chen F, Wang H. Development of a fusion protein SNVP as substrate for assaying multi-serotype botulinum neurotoxins. Anal Biochem 2013; 463:75-81. [PMID: 23851341 DOI: 10.1016/j.ab.2013.06.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 06/19/2013] [Accepted: 06/24/2013] [Indexed: 10/26/2022]
Abstract
The SNARE super family has three core members, namely SNAP-25, VAMP-2, and syntaxin. SNAP-25 is cleaved by botulinum toxins (BoNTs)/A, /C, and /E, whereas VAMP-2 is the substrate for proteolytic BoNTs/B, /D, /F, and /G. In this study, we constructed a hybrid gene encoding the fusion protein SNVP that encompasses SNAP-25 residues Met1 to Gly206 and VAMP-2 residues Met1 to Lys94. The hybrid gene was cloned in a prokaryotic vector carrying an N-terminal pelB signal sequence and overexpressed in Escherichia coli BL21(DE3) Rosetta. To easily purify the protein, 6× His double-affinity tags were designed as the linker and C terminus of the fusion protein. SNVP was purified to homogeneity by affinity chromatography on a HisTrap FF column and determined to be more than 97% pure by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. N-terminal sequencing of the purified protein showed that signal peptide was successfully removed. The fusion protein SNVP contained the protease cleavage sites of all seven serotypes of BoNTs. SNVP was also proved to be recognized and cleaved by the endopeptidase of BoNTs (BoNT/A-LC, BoNT/B-LC, BoNT/E-LC, and BoNT/G-LC). The novel fusion substrate SNVP exhibited high biological activity under the optimal conditions, suggesting its potential use as a reagent for BoNT assay.
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Affiliation(s)
- Sen Luo
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China; Department of Microbiology, An Hui Medical University, An Hui 230032, PR China
| | - Tao Li
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China
| | - Qin Wang
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China
| | - Renmao Tian
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China
| | - Hao Liu
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China
| | - Huali Fang
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China
| | - Fanghong Chen
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China
| | - Hui Wang
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, PR China.
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12
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Fernández-Salas E, Wang J, Molina Y, Nelson JB, Jacky BPS, Aoki KR. Botulinum neurotoxin serotype A specific cell-based potency assay to replace the mouse bioassay. PLoS One 2012. [PMID: 23185348 PMCID: PMC3504020 DOI: 10.1371/journal.pone.0049516] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Botulinum neurotoxin serotype A (BoNT/A), a potent therapeutic used to treat various disorders, inhibits vesicular neurotransmitter exocytosis by cleaving SNAP25. Development of cell-based potency assays (CBPAs) to assess the biological function of BoNT/A have been challenging because of its potency. CBPAs can evaluate the key steps of BoNT action: receptor binding, internalization-translocation, and catalytic activity; and therefore could replace the current mouse bioassay. Primary neurons possess appropriate sensitivity to develop potential replacement assays but those potency assays are difficult to perform and validate. This report describes a CBPA utilizing differentiated human neuroblastoma SiMa cells and a sandwich ELISA that measures BoNT/A-dependent intracellular increase of cleaved SNAP25. Assay sensitivity is similar to the mouse bioassay and measures neurotoxin biological activity in bulk drug substance and BOTOX® product (onabotulinumtoxinA). Validation of a version of this CBPA in a Quality Control laboratory has led to FDA, Health Canada, and European Union approval for potency testing of BOTOX®, BOTOX® Cosmetic, and Vistabel®. Moreover, we also developed and optimized a BoNT/A CBPA screening assay that can be used for the discovery of novel BoNT/A inhibitors to treat human disease.
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Affiliation(s)
- Ester Fernández-Salas
- Department of Biological Sciences, Allergan Inc., Irvine, California, United States of America.
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Wang D, Baudys J, Ye Y, Rees JC, Barr JR, Pirkle JL, Kalb SR. Improved detection of botulinum neurotoxin serotype A by Endopep-MS through peptide substrate modification. Anal Biochem 2012; 432:115-23. [PMID: 23017875 DOI: 10.1016/j.ab.2012.09.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 09/10/2012] [Accepted: 09/17/2012] [Indexed: 11/16/2022]
Abstract
Botulinum neurotoxins (BoNTs) are a family of seven toxin serotypes that are the most toxic substances known to humans. Intoxication with BoNT causes flaccid paralysis and can lead to death if untreated with serotype-specific antibodies. Supportive care, including ventilation, may be necessary. Rapid and sensitive detection of BoNT is necessary for timely clinical confirmation of clinical botulism. Previously, our laboratory developed a fast and sensitive mass spectrometry (MS) method termed the Endopep-MS assay. The BoNT serotypes are rapidly detected and differentiated by extracting the toxin with serotype-specific antibodies and detecting the unique and serotype-specific cleavage products of peptide substrates that mimic the sequence of the BoNT native targets. To further improve the sensitivity of the Endopep-MS assay, we report here the optimization of the substrate peptide for the detection of BoNT/A. Modifications on the terminal groups of the original peptide substrate with acetylation and amidation significantly improved the detection of BoNT/A cleavage products. The replacement of some internal amino acid residues with single or multiple substitutions led to further improvement. An optimized peptide increased assay sensitivity 5-fold with toxin spiked into buffer solution or different biological matrices.
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Affiliation(s)
- Dongxia Wang
- National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA
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Detection of botulinum neurotoxin serotype A, B, and F proteolytic activity in complex matrices with picomolar to femtomolar sensitivity. Appl Environ Microbiol 2012; 78:7687-97. [PMID: 22923410 DOI: 10.1128/aem.01664-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Rapid, high-throughput assays that detect and quantify botulinum neurotoxin (BoNT) activity in diverse matrices are required for environmental, clinical, pharmaceutical, and food testing. The current standard, the mouse bioassay, is sensitive but is low in throughput and precision. In this study, we present three biochemical assays for the detection and quantification of BoNT serotype A, B, and F proteolytic activities in complex matrices that offer picomolar to femtomolar sensitivity with small assay volumes and total assay times of less than 24 h. These assays consist of magnetic beads conjugated with BoNT serotype-specific antibodies that are used to purify BoNT from complex matrices before the quantification of bound BoNT proteolytic activity using the previously described BoTest reporter substrates. The matrices tested include human serum, whole milk, carrot juice, and baby food, as well as buffers containing common pharmaceutical excipients. The limits of detection were below 1 pM for BoNT/A and BoNT/F and below 10 pM for BoNT/B in most tested matrices using 200-μl samples and as low as 10 fM for BoNT/A with an increased sample volume. Together, these data describe rapid, robust, and high-throughput assays for BoNT detection that are compatible with a wide range of matrices.
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Liu YY, Rigsby P, Sesardic D, Marks JD, Jones RG. A functional dual-coated (FDC) microtiter plate method to replace the botulinum toxin LD50 test. Anal Biochem 2012; 425:28-35. [DOI: 10.1016/j.ab.2012.02.038] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 02/24/2012] [Accepted: 02/28/2012] [Indexed: 11/17/2022]
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16
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Functional protease assay using liquid crystals as a signal reporter. Biosens Bioelectron 2012; 35:174-179. [DOI: 10.1016/j.bios.2012.02.042] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 02/18/2012] [Accepted: 02/20/2012] [Indexed: 11/22/2022]
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17
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Joshi SG. Detection of biologically active botulinum neurotoxin-A in serum using high-throughput FRET-assay. J Pharmacol Toxicol Methods 2012; 65:8-12. [PMID: 22178409 DOI: 10.1016/j.vascn.2011.11.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Revised: 11/16/2011] [Accepted: 11/25/2011] [Indexed: 10/14/2022]
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18
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Dorner MB, Schulz KM, Kull S, Dorner BG. Complexity of Botulinum Neurotoxins: Challenges for Detection Technology. Curr Top Microbiol Immunol 2012. [DOI: 10.1007/978-3-662-45790-0_11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Wang W, Wang L, Zou Y, Zhang J, Gong Q, Wu J, Shi Y. Cooperation of Escherichia coli Hfq hexamers in DsrA binding. Genes Dev 2011; 25:2106-17. [PMID: 21979921 DOI: 10.1101/gad.16746011] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Hfq is a bacterial post-transcriptional regulator. It facilitates base-pairing between sRNA and target mRNA. Hfq mediates DsrA-dependent translational activation of rpoS mRNA at low temperatures. rpoS encodes the stationary-phase σ factor σ(S), which is the central regulator in general stress response. However, structural information on Hfq-DsrA interaction is not yet available. Although Hfq is reported to hydrolyze ATP, the ATP-binding site is still unknown. Here, we report a ternary crystal complex structure of Escherichia coli Hfq bound to a major Hfq recognition region on DsrA (AU(6)A) together with ADP, and a crystal complex structure of Hfq bound to ADP. AU(6)A binds to the proximal and distal sides of two Hfq hexamers. ADP binds to a purine-selective site on the distal side and contacts conserved arginine or glutamine residues on the proximal side of another hexamer. This binding mode is different from previously postulated. The cooperation of two different Hfq hexamers upon nucleic acid binding in solution is verified by fluorescence polarization and solution nuclear magnetic resonance (NMR) experiments using fragments of Hfq and DsrA. Fluorescence resonance energy transfer conducted with full-length Hfq and DsrA also supports cooperation of Hfq hexamers upon DsrA binding. The implications of Hfq hexamer cooperation have been discussed.
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Affiliation(s)
- Weiwei Wang
- Hefei National Laboratory for Physical Sciences at Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
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In vitro detection and quantification of botulinum neurotoxin type e activity in avian blood. Appl Environ Microbiol 2011; 77:7815-22. [PMID: 21908624 DOI: 10.1128/aem.06165-11] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Botulinum neurotoxin serotype E (BoNT/E) outbreaks in the Great Lakes region cause large annual avian mortality events, with an estimated 17,000 bird deaths reported in 2007 alone. During an outbreak investigation, blood collected from bird carcasses is tested for the presence of BoNT/E using the mouse lethality assay. While sensitive, this method is labor-intensive and low throughput and can take up to 7 days to complete. We developed a rapid and sensitive in vitro assay, the BoTest Matrix E assay, that combines immunoprecipitation with high-affinity endopeptidase activity detection by Förster resonance energy transfer (FRET) to rapidly quantify BoNT/E activity in avian blood with detection limits comparable to those of the mouse lethality assay. On the basis of the analysis of archived blood samples (n = 87) collected from bird carcasses during avian mortality investigations, BoTest Matrix E detected picomolar quantities of BoNT/E following a 2-h incubation and femtomolar quantities of BoNT/E following extended incubation (24 h) with 100% diagnostic specificity and 91% diagnostic sensitivity.
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Characterization of Förster resonance energy transfer in a botulinum neurotoxin protease assay. Anal Biochem 2011; 413:43-9. [DOI: 10.1016/j.ab.2011.01.045] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 01/28/2011] [Accepted: 01/29/2011] [Indexed: 11/22/2022]
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