1
|
Characterization of immune response induced against catalytic domain of botulinum neurotoxin type E. Sci Rep 2020; 10:13932. [PMID: 32811892 PMCID: PMC7434876 DOI: 10.1038/s41598-020-70929-8] [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: 01/20/2020] [Accepted: 07/21/2020] [Indexed: 11/08/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) represent a family of bacterial toxins responsible for neuroparalytic disease 'botulism' in human and animals. Their potential use as biological weapon led to their classification in category 'A' biowarfare agent by Centers for Disease Control and Prevention (CDC), USA. In present study, gene encoding full length catalytic domain of BoNT/E-LC was cloned, expressed and protein was purified using Ni-NTA chromatography. Humoral immune response was confirmed by Ig isotyping and cell-mediated immunity by cytokine profiling and intracellular staining for enumeration of IFN-γ secreting CD4+ and CD8+ T cells. Increased antibody titer with the predominance of IgG subtype was observed. An interaction between antibodies produced against rBoNT/E-LC was established that showed the specificity against BoNT/E in SPR assay. Animal protection with rBoNT/E-LC was conferred through both humoral and cellular immune responses. These findings were supported by cytokine profiling and flow cytometric analysis. Splenocytes stimulated with rBoNT/E-LC showed a 3.27 and 2.8 times increase in the IFN-γ secreting CD4+ and CD8+ T cells, respectively; in immunized group (P < 0.05). Protection against BoNT/E challenge tended to relate with increase in the percentage of rBoNT/E-LC specific IL-2 in the splenocytes supernatant (P = 0.034) and with IFN-γ-producing CD4+ T cell responses (P = 0.045). We have immunologically evaluated catalytically active rBoNT/E-LC. Our results provide valuable investigational report for immunoprophylactic role of catalytic domain of BoNT/E.
Collapse
|
2
|
A Short Peptide Designed from Late Embryogenesis Abundant Protein Enhances Acid Tolerance in Escherichia coli. Appl Biochem Biotechnol 2020; 191:164-176. [PMID: 32096062 DOI: 10.1007/s12010-020-03262-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 02/13/2020] [Indexed: 01/09/2023]
Abstract
Unsuitable pH is a major limiting factor for all organisms, and a low pH can lead to organism death. Late embryogenesis abundant (LEA) peptides confer tolerance to abiotic stresses including salinity, drought, high and low temperature, and ultraviolet radiation same as the LEA proteins from which they originate. In this study, LEA peptides derived from group 3 LEA proteins of Polypedilum vanderplanki were used to enhance low pH tolerance. Recombinant Escherichia coli BL21 (DE3) cells expressing the five designed LEA peptides were grown at pH 4, 3, and 2. The transformants showed higher growth capacity at low pH as compared to control cells. These results indicate that LEA peptide could prevent E. coli cell death under low pH conditions.
Collapse
|
3
|
Chauhan R, Chauhan V, Rao MK, Chaudhary D, Bhagyawant S, Dhaked RK. High level expression and immunochemical characterization of botulinum neurotoxin type F light chain. Protein Expr Purif 2018; 146:51-60. [PMID: 29407166 DOI: 10.1016/j.pep.2018.01.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 01/16/2018] [Accepted: 01/27/2018] [Indexed: 11/15/2022]
Abstract
Botulinum neurotoxins (BoNTs) are the most toxic biological substances known. Their potential use as biological warfare agent results in their classification as category A biowarfare agent by Centers for Disease Control and Prevention (CDC), USA. Presently, there are no approved detection system and pharmacological treatments for BoNT intoxication. Although a toxoid vaccine is available for immuno-prophylaxis, vaccines cannot reverse the effect of pre-translocated toxin. Direct handling of the live BoNTs for developing detection and therapeutics may pose fatal danger. This concern was addressed by purifying the recombinant catalytically active light chain of BoNT/F. BoNT/F-LC gene was amplified from the genomic DNA using specifically designed primers and expressed in Escherichia coli. Expression and purification profile were optimized under different conditions for biologically active light chain production. Specific polyclonal antibodies generated against type F illustrates in vivo neutralization in mice and rabbit. These antibodies play key role in conceiving the development of high throughput SPR based detection system which is a highly precise label free technique for protein interaction analysis. The presented work is first of its kind, signifying the production of highly stable and active rBoNT/F-LC and its immunochemical characterization. The study aids in paving the path towards developing a persistent detection system as well as in presenting comprehended scheme for in vitro small molecule therapeutics analysis.
Collapse
Affiliation(s)
| | | | - Mula Kameshwar Rao
- Division of Pharmacology and Toxicology, Defence Research & Development Establishment, Jhansi Road, Gwalior 474002, India
| | | | - Sameer Bhagyawant
- School of Studies in Biotechnology, Jiwaji University, Gwalior 474001, India
| | | |
Collapse
|
4
|
Wang Y, Montana V, Grubišić V, Stout RF, Parpura V, Gu LQ. Nanopore sensing of botulinum toxin type B by discriminating an enzymatically cleaved Peptide from a synaptic protein synaptobrevin 2 derivative. ACS APPLIED MATERIALS & INTERFACES 2015; 7:184-92. [PMID: 25511125 PMCID: PMC4296922 DOI: 10.1021/am5056596] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Botulinum neurotoxins (BoNTs) are the most lethal toxin known to human. Biodefense requires early and rapid detection of BoNTs. Traditionally, BoNTs can be detected by looking for signs of botulism in mice that receive an injection of human material, serum or stool. While the living animal assay remains the most sensitive approach, it is costly, slow and associated with legal and ethical constrains. Various biochemical, optical and mechanical methods have been developed for BoNTs detection with improved speed, but with lesser sensitivity. Here, we report a novel nanopore-based BoNT type B (BoNT-B) sensor that monitors the toxin's enzymatic activity on its substrate, a recombinant synaptic protein synaptobrevin 2 derivative. By analyzing the modulation of the pore current caused by the specific BoNT-B-digested peptide as a marker, the presence of BoNT-B at a subnanomolar concentration was identified within minutes. The nanopore detector would fill the niche for a much needed rapid and highly sensitive detection of neurotoxins, and provide an excellent system to explore biophysical mechanisms for biopolymer transportation.
Collapse
Affiliation(s)
- Yong Wang
- Department
of Bioengineering and Dalton Cardiovascular Research
Center, University of Missouri, Columbia, Missouri 65211, United States
- Dr. Yong Wang. E-mail:
| | - Vedrana Montana
- Department
of Neurobiology, Center for Glial Biology in Medicine,
Atomic Force Microscopy & Nanotechnology Laboratories, Civitan
International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
- Department of Biotechnology, University of Rijeka, 51000 Rijeka, Croatia
| | - Vladimir Grubišić
- Department
of Neurobiology, Center for Glial Biology in Medicine,
Atomic Force Microscopy & Nanotechnology Laboratories, Civitan
International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
| | - Randy F. Stout
- Department
of Neurobiology, Center for Glial Biology in Medicine,
Atomic Force Microscopy & Nanotechnology Laboratories, Civitan
International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
- Department of Neuroscience, Albert Einstein
College of Medicine, Bronx, New
York, New York 10461, United States
| | - Vladimir Parpura
- Department
of Neurobiology, Center for Glial Biology in Medicine,
Atomic Force Microscopy & Nanotechnology Laboratories, Civitan
International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, Alabama 35294, United States
- Department of Biotechnology, University of Rijeka, 51000 Rijeka, Croatia
- Dr. Vladimir Parpura.
E-mail:
| | - Li-Qun Gu
- Department
of Bioengineering and Dalton Cardiovascular Research
Center, University of Missouri, Columbia, Missouri 65211, United States
- Dr. Li-Qun Gu. E-mail:
| |
Collapse
|
5
|
Production of recombinant botulism antigens: A review of expression systems. Anaerobe 2014; 28:130-6. [DOI: 10.1016/j.anaerobe.2014.06.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Revised: 06/03/2014] [Accepted: 06/03/2014] [Indexed: 11/18/2022]
|
6
|
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.
Collapse
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
| |
Collapse
|
7
|
Abstract
Botulism is a severe neuroparalytic disease caused by the toxins produced from several Clostridium species. Botulinum neurotoxins (BoNTs) cause flaccid paralysis by inducing a blockade at voluntary motor and autonomic cholinergic junctions that, if not treated, can be fatal. Vaccination to elicit protective circulating antibodies that bind, neutralize and clear toxins before they can be internalized and affect cholinergic neurons remains the most effective form of protection against BoNT. A pentavalent BoNT toxoid vaccine administered in the USA under an Investigational New Drug protocol to at-risk workers was discontinued by the CDC in 2011 due to diminished potency and reactogenic effects. Subsequent research efforts have primarily focused on recombinant protein antigens. This review focuses on the development of a recombinant bivalent vaccine (rBV A/B) composed of purified recombinant BoNT/A and BoNT/B receptor-binding domain proteins, as well as presenting a summary of progress and issues associated with alternative vaccines currently being developed against botulism.
Collapse
Affiliation(s)
- Robert P Webb
- US Army Medical Research Institute for Infectious Diseases, Frederick, MD 21702, USA
| | | |
Collapse
|
8
|
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.
Collapse
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.
| |
Collapse
|
9
|
Mizanur RM, Frasca V, Swaminathan S, Bavari S, Webb R, Smith LA, Ahmed SA. The C terminus of the catalytic domain of type A botulinum neurotoxin may facilitate product release from the active site. J Biol Chem 2013; 288:24223-33. [PMID: 23779108 DOI: 10.1074/jbc.m113.451286] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Botulinum neurotoxins are the most toxic of all compounds. The toxicity is related to a poor zinc endopeptidase activity located in a 50-kDa domain known as light chain (Lc) of the toxin. The C-terminal tail of Lc is not visible in any of the currently available x-ray structures, and it has no known function but undergoes autocatalytic truncations during purification and storage. By synthesizing C-terminal peptides of various lengths, in this study, we have shown that these peptides competitively inhibit the normal catalytic activity of Lc of serotype A (LcA) and have defined the length of the mature LcA to consist of the first 444 residues. Two catalytically inactive mutants also inhibited LcA activity. Our results suggested that the C terminus of LcA might interact at or near its own active site. By using synthetic C-terminal peptides from LcB, LcC1, LcD, LcE, and LcF and their respective substrate peptides, we have shown that the inhibition of activity is specific only for LcA. Although a potent inhibitor with a Ki of 4.5 μm, the largest of our LcA C-terminal peptides stimulated LcA activity when added at near-stoichiometric concentration to three versions of LcA differing in their C-terminal lengths. The result suggested a product removal role of the LcA C terminus. This suggestion is supported by a weak but specific interaction determined by isothermal titration calorimetry between an LcA C-terminal peptide and N-terminal product from a peptide substrate of LcA. Our results also underscore the importance of using a mature LcA as an inhibitor screening target.
Collapse
Affiliation(s)
- Rahman M Mizanur
- Integrated Toxicology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland 21702, USA
| | | | | | | | | | | | | |
Collapse
|
10
|
Meng Q, Garcia-Rodriguez C, Manzanarez G, Silberg MA, Conrad F, Bettencourt J, Pan X, Breece T, To R, Li M, Lee D, Thorner L, Tomic MT, Marks JD. Engineered domain-based assays to identify individual antibodies in oligoclonal combinations targeting the same protein. Anal Biochem 2012; 430:141-50. [PMID: 22922799 DOI: 10.1016/j.ab.2012.08.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 07/29/2012] [Accepted: 08/07/2012] [Indexed: 11/28/2022]
Abstract
Quantitation of individual monoclonal antibodies (mAbs) within a combined antibody drug product is required for preclinical and clinical drug development. We have developed two antitoxins, XOMA 3B and XOMA 3E, each consisting of three mAbs that neutralize type B and type E botulinum neurotoxin (BoNT/B and BoNT/E) to treat serotype B and E botulism. To develop mAb-specific binding assays for each antitoxin, we mapped the epitopes of the six mAbs. Each mAb bound an epitope on either the BoNT light chain (LC) or translocation domain (H(N)). Epitope mapping data were used to design LC-H(N) domains with orthogonal mutations to make them specific for only one mAb in either XOMA 3B or XOMA 3E. Mutant LC-H(N) domains were cloned, expressed, and purified from Escherichia coli. Each mAb bound only to its specific domain with affinity comparable to the binding to holotoxin. Further engineering of domains allowed construction of enzyme-linked immunosorbent assays (ELISAs) that could characterize the integrity, binding affinity, and identity of each of the six mAbs in XOMA 3B and 3E without interference from the three BoNT/A mAbs in XOMA 3AB. Such antigen engineering is a general method allowing quantitation and characterization of individual mAbs in a mAb cocktail that bind the same protein.
Collapse
Affiliation(s)
- Q Meng
- Department of Anesthesia, University of California, San Francisco, San Francisco General Hospital, San Francisco, CA 94110, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Toth S, Brueggmann EE, Oyler GA, Smith LA, Hines HB, Ahmed SA. Tyrosine phosphorylation of botulinum neurotoxin protease domains. Front Pharmacol 2012; 3:102. [PMID: 22675300 PMCID: PMC3366388 DOI: 10.3389/fphar.2012.00102] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 05/07/2012] [Indexed: 01/17/2023] Open
Abstract
Botulinum neurotoxins are most potent of all toxins. Their N-terminal light chain domain (Lc) translocates into peripheral cholinergic neurons to exert its endoproteolytic action leading to muscle paralysis. Therapeutic development against these toxins is a major challenge due to their in vitro and in vivo structural differences. Although three-dimensional structures and reaction mechanisms are very similar, the seven serotypes designated A through G vastly vary in their intracellular catalytic stability. To investigate if protein phosphorylation could account for this difference, we employed Src-catalyzed tyrosine phosphorylation of the Lc of six serotypes namely LcA, LcB, LcC1, LcD, LcE, and LcG. Very little phosphorylation was observed with LcD and LcE but LcA, LcB, and LcG were maximally phosphorylated by Src. Phosphorylation of LcA, LcB, and LcG did not affect their secondary and tertiary structures and thermostability significantly. Phosphorylation of Y250 and Y251 made LcA resistant to autocatalysis and drastically reduced its kcat/Km for catalysis. A tyrosine residue present near the essential cysteine at the C-terminal tail of LcA, LcB, and LcG was readily phosphorylated in vitro. Inclusion of a competitive inhibitor protected Y426 of LcA from phosphorylation, shedding light on the role of the C-terminus in the enzyme’s substrate or product binding.
Collapse
Affiliation(s)
- Stephen Toth
- Integrated Toxicology Division, Department of Biochemistry and Cell Biology, United States Army Medical Research Institute of Infectious Diseases Fort Detrick, MD, USA
| | | | | | | | | | | |
Collapse
|
12
|
A label-free biosensor assay for botulinum neurotoxin B in food and human serum. Anal Biochem 2011; 410:281-8. [DOI: 10.1016/j.ab.2010.11.045] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 11/25/2010] [Accepted: 11/30/2010] [Indexed: 11/20/2022]
|
13
|
Hale M, Oyler G, Swaminathan S, Ahmed SA. Basic tetrapeptides as potent intracellular inhibitors of type A botulinum neurotoxin protease activity. J Biol Chem 2010; 286:1802-11. [PMID: 20961849 DOI: 10.1074/jbc.m110.146464] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Botulinum neurotoxins (BoNT) are the most potent of all toxins that cause flaccid muscle paralysis leading to death. They are also potential biothreat agents. A systematic investigation of various short peptide inhibitors of the BoNT protease domain with a 17-residue peptide substrate led to arginine-arginine-glycine-cysteine having a basic tetrapeptide structure as the most potent inhibitor. When assayed in the presence of dithiothreitol (DTT), the inhibitory effect was drastically reduced. Replacing the terminal cysteine with one hydrophobic residue eliminated the DTT effect but with two hydrophobic residues made the pentapeptide a poor inhibitor. Replacing the first arginine with cysteine or adding an additional cysteine at the N terminus did not improve inhibition. When assessed using mouse brain lysates, the tetrapeptides also inhibited BoNT/A cleavage of the endogenous SNAP-25. The peptides penetrated the neuronal cell lines, N2A and BE(2)-M17, without adversely affecting metabolic functions as measured by ATP production and P-38 phosphorylation. Biological activity of the peptides persisted within cultured chick motor neurons and rat and mouse cerebellar neurons for more than 40 h and inhibited BoNT/A protease action inside the neurons in a dose- and time-dependent fashion. Our results define a tetrapeptide as the smallest peptide inhibitor in the backdrop of a large substrate protein of 200+ amino acids having multiple interaction regions with its cognate enzyme. The inhibitors should also be valuable candidates for drug development.
Collapse
Affiliation(s)
- Martha Hale
- Department Cell Biology and Biochemistry, Integrated Toxicology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland 21702, USA
| | | | | | | |
Collapse
|
14
|
Endopeptidase activities of botulinum neurotoxin type B complex, holotoxin, and light chain. Appl Environ Microbiol 2010; 76:6658-63. [PMID: 20693440 DOI: 10.1128/aem.00731-10] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Botulinum neurotoxin (BoNT) serotype B (BoNT/B) is one of the serotypes of BoNT that causes deadly human botulism, though it is used clinically for treatment of many neuromuscular diseases. BoNT/B is produced by Clostridium botulinum, and it is secreted along with a group of neurotoxin-associated proteins (NAPs) in the form of a BoNT/B complex. The complex dissociates into a 150-kDa holotoxin and NAPs at alkaline pHs. The 150-kDa BoNT/B holotoxin can be nicked to produce a 50-kDa domain referred to as the light chain (LC) and a 100-kDa heavy chain, with the former possessing a unique endopeptidase activity. The two chains remain linked through a disulfide bond that can be reduced to separate the two chains. The endopeptidase activity is present in all three forms of the toxin (complex, purified BoNT/B holotoxin, and separated light chain), which are used by different researchers to develop detection methods and screen for inhibitors. In this research, the endopeptidase activities of the three forms, for the first time, were compared under the same conditions. The results show that enzyme activities of the three forms differ significantly and are largely dependent on nicking and disulfide reduction conditions. Under the conditions used, LC had the highest level of activity, and the complex had the lowest. The activity was enhanced by nicking of BoNT/B holotoxin and was enhanced even more by dithiothreitol (DTT) reduction after nicking. This information is useful for understanding the properties of BoNT endopeptidases and for comparing the efficacies of different inhibitors when they are tested with different forms of BoNT endopeptidase.
Collapse
|
15
|
Improved soluble expression and characterization of the Hc domain of Clostridium botulinum neurotoxin serotype A in Escherichia coli by using a PCR-synthesized gene and a Trx co-expression strain. Protein Expr Purif 2010; 71:79-84. [DOI: 10.1016/j.pep.2009.11.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2009] [Revised: 11/13/2009] [Accepted: 11/14/2009] [Indexed: 11/19/2022]
|
16
|
Vaccination of rabbits with an alkylated toxoid rapidly elicits potent neutralizing antibodies against botulinum neurotoxin serotype B. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2010; 17:930-6. [PMID: 20410329 DOI: 10.1128/cvi.00493-09] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
New Zealand White (NZW) rabbits were immunized with several different nontoxic botulinum neurotoxin serotype B (BoNT/B) preparations in an effort to optimize the production of a rapid and highly potent, effective neutralizing antibody response. The immunogens included a recombinant heavy chain (rHc) protein produced in Escherichia coli, a commercially available formaldehyde-inactivated toxoid, and an alkylated toxoid produced by urea-iodoacetamide inactivation of the purified active toxin. All three immunogens elicited an antibody response to BoNT/B, detected by enzyme-linked immunosorbent assay (ELISA) and by toxin neutralization assay, by the use of two distinct mouse toxin challenge models. The induction period and the ultimate potency of the observed immune response varied for each immunogen, and the ELISA titer was not reliably predictive of the potency of toxin neutralization. The kinetics of the BoNT/B-specific binding immune response were nearly identical for the formaldehyde toxoid and alkylated toxoid immunogens, but immunization with the alkylated toxoid generated an approximately 10-fold higher neutralization potency that endured throughout the study, and after just 49 days, each milliliter of serum was capable of neutralizing 10(7) 50% lethal doses of the toxin. Overall, the immunization of rabbits with alkylated BoNT/B toxoid appears to have induced a neutralizing immune response more rapid and more potent than the responses generated by vaccination with formaldehyde toxoid or rHc preparations.
Collapse
|
17
|
Rowe B, Schmidt JJ, Smith LA, Ahmed SA. Rapid product analysis and increased sensitivity for quantitative determinations of botulinum neurotoxin proteolytic activity. Anal Biochem 2010; 396:188-93. [DOI: 10.1016/j.ab.2009.09.034] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Revised: 09/18/2009] [Accepted: 09/20/2009] [Indexed: 10/20/2022]
|
18
|
Botulism and vaccines for its prevention. Vaccine 2009; 27 Suppl 4:D33-9. [DOI: 10.1016/j.vaccine.2009.08.059] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Accepted: 08/11/2009] [Indexed: 11/19/2022]
|
19
|
Toth SI, Smith LA, Ahmed SA. Extreme sensitivity of botulinum neurotoxin domains towards mild agitation. J Pharm Sci 2009; 98:3302-11. [PMID: 19226630 DOI: 10.1002/jps.21676] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Botulinum neurotoxins (BoNTs) and their fragments are targets of therapeutic developments and are increasingly used as therapeutic, prophylactic, and research reagents. However, published data on their properties vary widely. In order to gain a better understanding of these variations, we initiated a systematic investigation of the stability parameters of catalytic light chains (Lc) as well as of cell surface binding domains (Hc) of the neurotoxin. When followed by CD spectroscopy, we noticed that the recombinant light chains of serotypes A (LcA), B, D, E, and G rapidly lost their secondary structures by mild stirring. Denaturation of LcA increased with stirring speed and temperature resulting in a catalytically inactive precipitate. Reducing agents or an anaerobic environment were ineffective in the denaturation. Under identical conditions, bovine serum albumin, ovalbumin, carboxypeptidase B, and of thermolysin, a structural and functional analogue of LcA, remained unchanged. Hc domains of serotype A, B, C, E, and F were also denatured by mild stirring. Adding the nonionic detergent Tween-20 to LcA completely prevented the denaturation. We speculate that the BoNT domains undergo surface denaturation due to rapid exposure of hydrophobic residues by mechanical agitation. This study has important implications for handling BoNT proteins used in therapeutic development.
Collapse
Affiliation(s)
- Stephen I Toth
- Department Molecular Biology, Integrated Toxicology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland 21702, USA
| | | | | |
Collapse
|
20
|
Identification and biochemical characterization of small-molecule inhibitors of Clostridium botulinum neurotoxin serotype A. Antimicrob Agents Chemother 2009; 53:3478-86. [PMID: 19528275 DOI: 10.1128/aac.00141-09] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An integrated strategy that combined in silico screening and tiered biochemical assays (enzymatic, in vitro, and ex vivo) was used to identify and characterize effective small-molecule inhibitors of Clostridium botulinum neurotoxin serotype A (BoNT/A). Virtual screening was initially performed by computationally docking compounds of the National Cancer Institute (NCI) database into the active site of BoNT/A light chain (LC). A total of 100 high-scoring compounds were evaluated in a high-performance liquid chromatography (HPLC)-based protease assay using recombinant full-length BoNT/A LC. Seven compounds that significantly inhibited the BoNT/A protease activity were selected. Database search queries of the best candidate hit [7-((4-nitro-anilino)(phenyl)methyl)-8-quinolinol (NSC 1010)] were performed to mine its nontoxic analogs. Fifty-five analogs of NSC 1010 were synthesized and examined by the HPLC-based assay. Of these, five quinolinol derivatives that potently inhibited both full-length BoNT/A LC and truncated BoNT/A LC (residues 1 to 425) were selected for further inhibition studies in neuroblastoma (N2a) cell-based and tissue-based mouse phrenic nerve hemidiaphragm assays. Consistent with enzymatic assays, in vitro and ex vivo studies revealed that these five quinolinol-based analogs effectively neutralized BoNT/A toxicity, with CB 7969312 exhibiting ex vivo protection at 0.5 microM. To date, this is the most potent BoNT/A small-molecule inhibitor that showed activity in an ex vivo assay. The reduced toxicity and high potency demonstrated by these five compounds at the biochemical, cellular, and tissue levels are distinctive among the BoNT/A small-molecule inhibitors reported thus far. This study demonstrates the utility of a multidisciplinary approach (in silico screening coupled with biochemical testing) for identifying promising small-molecule BoNT/A inhibitors.
Collapse
|
21
|
Hines HB, Kim AD, Stafford RG, Badie SS, Brueggeman EE, Newman DJ, Schmidt JJ. Use of a recombinant fluorescent substrate with cleavage sites for all botulinum neurotoxins in high-throughput screening of natural product extracts for inhibitors of serotypes A, B, and E. Appl Environ Microbiol 2008; 74:653-9. [PMID: 18083881 PMCID: PMC2227718 DOI: 10.1128/aem.01690-07] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 11/26/2007] [Indexed: 11/20/2022] Open
Abstract
The seven serotypes of botulinum neurotoxin (BoNTs) are zinc metalloproteases that cleave and inactivate proteins critical for neurotransmission. The synaptosomal protein of 25 kDa (SNAP-25) is cleaved by BoNTs A, C, and E, while vesicle-associated membrane protein (VAMP) is the substrate for BoNTs B, D, F, and G. BoNTs not only are medically useful drugs but also are potential bioterrorist and biowarfare threat agents. Because BoNT protease activity is required for toxicity, inhibitors of that activity might be effective for antibotulinum therapy. To expedite inhibitor discovery, we constructed a hybrid gene encoding (from the N terminus to the C terminus, with respect to the expressed product) green fluorescent protein, then a SNAP-25 fragment encompassing residues Met-127 to Gly-206, and then VAMP residues Met-1 to Lys-94. Cysteine was added as the C terminus. The expressed product, which contained the protease cleavage sites for all seven botulinum serotypes, was purified and coupled covalently through the C-terminal sulfhydryl group to maleimide-activated 96-well plates. The substrate was readily cleaved by BoNTs A, B, D, E, and F. Using this assay and an automated 96-well pipettor, we screened 528 natural product extracts for inhibitors of BoNT A, B, and E protease activities. Serotype-specific inhibition was found in 30 extracts, while 5 others inhibited two serotypes.
Collapse
Affiliation(s)
- Harry B Hines
- Department of Cell Biology and Biochemistry, Integrated Toxicology Division, USAMRIID, Frederick, MD 21702-5011, USA
| | | | | | | | | | | | | |
Collapse
|
22
|
Paliy O, Gunasekera TS. Growth of E. coli BL21 in minimal media with different gluconeogenic carbon sources and salt contents. Appl Microbiol Biotechnol 2006; 73:1169-72. [PMID: 16944129 DOI: 10.1007/s00253-006-0554-8] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2006] [Revised: 06/20/2006] [Accepted: 06/21/2006] [Indexed: 11/26/2022]
Abstract
Escherichia coli strain BL21 is commonly used as a host strain for protein expression and purification. For structural analysis, proteins are frequently isotopically labeled with deuterium (2H), 13C, or 15N by growing E. coli cultures in a medium containing the appropriate isotope. When large quantities of fully deuterated proteins are required, E. coli is often grown in minimal media with deuterated succinate or acetate as the carbon source because these are less expensive. Despite the widespread use of BL21, we found no data on the effect of different minimal media and carbon sources on BL21 growth. In this study, we assessed the growth behavior of E. coli BL21 in minimal media with different gluconeogenic carbon sources. Though BL21 grew reasonably well on glycerol and pyruvate, it had a prolonged lag-phase on succinate (20 h), acetate (10 h), and fumarate (20 h), attributed to the physiological adaptation of E. coli cells. Wild-type strain NCM3722 (K12) grew well on all the substrates. We also examined the growth of E. coli BL21 in minimal media that differed in their salt composition but not in their source of carbon. The commonly used M9 medium did not support the optimum growth of E. coli BL21 in minimal medium. The addition of ferrous sulphate to M9 medium (otherwise lacking it) increased the growth rate of E. coli cultures and significantly increased their cell density in the stationary phase.
Collapse
Affiliation(s)
- Oleg Paliy
- Department of Biochemistry and Molecular Biology, Wright State University, 256 BioSciences, 3640 Col. Glenn Hwy, Dayton, OH 45435, USA.
| | | |
Collapse
|