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Rudnicka K, Durka K, Chwaluk P, Chmiela M. Metody stosowane do wykrywania i identyfikacji toksyn botulinowych w próbkach klinicznych i żywności*. POSTEP HIG MED DOSW 2020. [DOI: 10.5604/01.3001.0014.1439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Botulism is a severe neuroparalytic illness, which affects the nervous system. It is caused by botulinum neurotoxins (BoNTs), produced by anaerobic gram-positive bacteria Clostridium botulinum. There are 7 serotypes of BoNT A-G, but BoNT A/B/D/E plays a major role in botulism affecting humans. Foodborne botulism (classic botulism) is the most frequent
clinical manifestation occurring after consumption of food containing botulinum neurotoxins.
The diagnosis of botulism is based on clinical symptoms; however, recommended
and alternative laboratory methods are used to confirm the etiology of symptoms and the
identification of BoNT toxin type. The aim of this work was to present the epidemiology of
foodborne botulism in Poland and to gather and analyze the available diagnostic methods
that allow us to detect BoNT in clinical samples. Using the epidemiological reports of National
Institute of Hygiene in Poland and findings presented in the Przegląd Epidemiologiczny,
the incidence of classical botulism in Poland has been presented over a period of recent
18 years. Searching for the optimal diagnostic method for BoNT identification in various
samples, we have confronted the sensitivity and specificity of recently available alternative
methods with classical biological assay.
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Affiliation(s)
- Karolina Rudnicka
- Pracownia Gastroimmunologii, Katedra Immunologii i Biologii Infekcyjnej, Wydział Biologii i Ochrony Środowiska, Uniwersytet Łódzki
| | - Karolina Durka
- Pracownia Gastroimmunologii, Katedra Immunologii i Biologii Infekcyjnej, Wydział Biologii i Ochrony Środowiska, Uniwersytet Łódzki
| | - Paweł Chwaluk
- Wojewódzki Szpital Specjalistyczny w Białej Podlaskiej, Biała Podlaska
| | - Magdalena Chmiela
- Pracownia Gastroimmunologii, Katedra Immunologii i Biologii Infekcyjnej, Wydział Biologii i Ochrony Środowiska, Uniwersytet Łódzki
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2
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Fan Y, Dong J, Lou J, Wen W, Conrad F, Geren IN, Garcia-Rodriguez C, Smith TJ, Smith LA, Ho M, Pires-Alves M, Wilson BA, Marks JD. Monoclonal Antibodies that Inhibit the Proteolytic Activity of Botulinum Neurotoxin Serotype/B. Toxins (Basel) 2015; 7:3405-23. [PMID: 26343720 PMCID: PMC4591640 DOI: 10.3390/toxins7093405] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 08/10/2015] [Accepted: 08/18/2015] [Indexed: 12/19/2022] Open
Abstract
Existing antibodies (Abs) used to treat botulism cannot enter the cytosol of neurons and bind to botulinum neurotoxin (BoNT) at its site of action, and thus cannot reverse paralysis. However, Abs targeting the proteolytic domain of the toxin could inhibit the proteolytic activity of the toxin intracellularly and potentially reverse intoxication, if they could be delivered intracellularly. As such, antibodies that neutralize toxin activity could serve as potent inhibitory cargos for therapeutic antitoxins against botulism. BoNT serotype B (BoNT/B) contains a zinc endopeptidase light chain (LC) domain that cleaves synaoptobrevin-2, a SNARE protein responsible for vesicle fusion and acetylcholine vesicle release. To generate monoclonal Abs (mAbs) that could reverse paralysis, we targeted the protease domain for Ab generation. Single-chain variable fragment (scFv) libraries from immunized mice or humans were displayed on yeast, and 19 unique BoNT/B LC-specific mAbs isolated by fluorescence-activated cell sorting (FACS). The equilibrium dissociation constants (KD) of these mAbs for BoNT/B LC ranged from 0.24 nM to 14.3 nM (mean KD 3.27 nM). Eleven mAbs inhibited BoNT/B LC proteolytic activity. The fine epitopes of selected mAbs were identified by alanine-scanning mutagenesis, revealing that inhibitory mAbs bound near the active site, substrate-binding site or the extended substrate-binding site. The results provide mAbs that could prove useful for intracellular reversal of paralysis and identify epitopes that could be targeted by small molecules inhibitors.
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Affiliation(s)
- Yongfeng Fan
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
| | - Jianbo Dong
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
| | - Jianlong Lou
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
| | - Weihua Wen
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
| | - Fraser Conrad
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
| | - Isin N Geren
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
| | - Consuelo Garcia-Rodriguez
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
| | - Theresa J Smith
- Molecular and Translational Sciences Division, United States Army Medical Institute of Infectious Diseases, Fort Detrick, MD 21702, USA.
| | - Leonard A Smith
- Medical Countermeasures Technology, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702-5011, USA.
| | - Mengfei Ho
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Melissa Pires-Alves
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Brenda A Wilson
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - James D Marks
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, San Francisco General Hospital, Room 3C-38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
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Monoclonal Antibodies Targeting the Alpha-Exosite of Botulinum Neurotoxin Serotype/A Inhibit Catalytic Activity. PLoS One 2015; 10:e0135306. [PMID: 26275214 PMCID: PMC4537209 DOI: 10.1371/journal.pone.0135306] [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: 04/05/2015] [Accepted: 07/20/2015] [Indexed: 12/12/2022] Open
Abstract
The paralytic disease botulism is caused by botulinum neurotoxins (BoNT), multi-domain proteins containing a zinc endopeptidase that cleaves the cognate SNARE protein, thereby blocking acetylcholine neurotransmitter release. Antitoxins currently used to treat botulism neutralize circulating BoNT but cannot enter, bind to or neutralize BoNT that has already entered the neuron. The light chain endopeptidase domain (LC) of BoNT serotype A (BoNT/A) was targeted for generation of monoclonal antibodies (mAbs) that could reverse paralysis resulting from intoxication by BoNT/A. Single-chain variable fragment (scFv) libraries from immunized humans and mice were displayed on the surface of yeast, and 19 BoNT/A LC-specific mAbs were isolated by using fluorescence-activated cell sorting (FACS). Affinities of the mAbs for BoNT/A LC ranged from a KD value of 9.0×10−11 M to 3.53×10−8 M (mean KD 5.38×10−9 M and median KD 1.53×10−9 M), as determined by flow cytometry analysis. Eleven mAbs inhibited BoNT/A LC catalytic activity with IC50 values ranging from 8.3 ~73×10−9 M. The fine epitopes of selected mAbs were also mapped by alanine-scanning mutagenesis, revealing that the inhibitory mAbs bound the α-exosite region remote from the BoNT/A LC catalytic center. The results provide mAbs that could prove useful for intracellular reversal of paralysis post-intoxication and further define epitopes that could be targeted by small molecule inhibitors.
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Patel V, Oh A, Voit A, Sultatos LG, Babu GJ, Wilson BA, Ho M, McArdle JJ. Altered active zones, vesicle pools, nerve terminal conductivity, and morphology during experimental MuSK myasthenia gravis. PLoS One 2014; 9:e110571. [PMID: 25438154 PMCID: PMC4249869 DOI: 10.1371/journal.pone.0110571] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 09/15/2014] [Indexed: 11/18/2022] Open
Abstract
Recent studies demonstrate reduced motor-nerve function during autoimmune muscle-specific tyrosine kinase (MuSK) myasthenia gravis (MG). To further understand the basis of motor-nerve dysfunction during MuSK-MG, we immunized female C57/B6 mice with purified rat MuSK ectodomain. Nerve-muscle preparations were dissected and neuromuscular junctions (NMJs) studied electrophysiologically, morphologically, and biochemically. While all mice produced antibodies to MuSK, only 40% developed respiratory muscle weakness. In vitro study of respiratory nerve-muscle preparations isolated from these affected mice revealed that 78% of NMJs produced endplate currents (EPCs) with significantly reduced quantal content, although potentiation and depression at 50 Hz remained qualitatively normal. EPC and mEPC amplitude variability indicated significantly reduced number of vesicle-release sites (active zones) and reduced probability of vesicle release. The readily releasable vesicle pool size and the frequency of large amplitude mEPCs also declined. The remaining NMJs had intermittent (4%) or complete (18%) failure of neurotransmitter release in response to 50 Hz nerve stimulation, presumably due to blocked action potential entry into the nerve terminal, which may arise from nerve terminal swelling and thinning. Since MuSK-MG-affected muscles do not express the AChR γ subunit, the observed prolongation of EPC decay time was not due to inactivity-induced expression of embryonic acetylcholine receptor, but rather to reduced catalytic activity of acetylcholinesterase. Muscle protein levels of MuSK did not change. These findings provide novel insight into the pathophysiology of autoimmune MuSK-MG.
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MESH Headings
- Animals
- Female
- Immunization, Passive
- Mice
- Motor Endplate/pathology
- Motor Endplate/physiopathology
- Motor Neurons/pathology
- Myasthenia Gravis, Autoimmune, Experimental/immunology
- Myasthenia Gravis, Autoimmune, Experimental/metabolism
- Myasthenia Gravis, Autoimmune, Experimental/pathology
- Myasthenia Gravis, Autoimmune, Experimental/physiopathology
- Neural Conduction
- Neurotransmitter Agents/metabolism
- Protein Structure, Tertiary
- Rats
- Receptor Protein-Tyrosine Kinases/chemistry
- Receptor Protein-Tyrosine Kinases/immunology
- Receptors, Cholinergic/metabolism
- Synaptic Vesicles/metabolism
- Vaccination
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Affiliation(s)
- Vishwendra Patel
- Department of Pharmacology and Physiology, New Jersey Medical School-Rutgers University, Newark, New Jersey, United States of America
| | - Anne Oh
- Department of Pharmacology and Physiology, New Jersey Medical School-Rutgers University, Newark, New Jersey, United States of America
| | - Antanina Voit
- Department Cell Biology and Molecular Medicine, New Jersey Medical School-Rutgers University, Newark, New Jersey, United States of America
| | - Lester G. Sultatos
- Department of Pharmacology and Physiology, New Jersey Medical School-Rutgers University, Newark, New Jersey, United States of America
| | - Gopal J. Babu
- Department Cell Biology and Molecular Medicine, New Jersey Medical School-Rutgers University, Newark, New Jersey, United States of America
| | - Brenda A. Wilson
- Department of Microbiology, University of Illinois, Urbana-Champaign, Illinois, United States of America
| | - Mengfei Ho
- Department of Microbiology, University of Illinois, Urbana-Champaign, Illinois, United States of America
| | - Joseph J. McArdle
- Department of Pharmacology and Physiology, New Jersey Medical School-Rutgers University, Newark, New Jersey, United States of America
- * E-mail:
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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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Caglič D, Bompiani KM, Krutein MC, Čapek P, Dickerson TJ. A high-throughput-compatible FRET-based platform for identification and characterization of botulinum neurotoxin light chain modulators. J Vis Exp 2013:50908. [PMID: 24430674 DOI: 10.3791/50908] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Botulinum neurotoxin (BoNT) is a potent and potentially lethal bacterial toxin that binds to host motor neurons, is internalized into the cell, and cleaves intracellular proteins that are essential for neurotransmitter release. BoNT is comprised of a heavy chain (HC), which mediates host cell binding and internalization, and a light chain (LC), which cleaves intracellular host proteins essential for acetylcholine release. While therapies that inhibit toxin binding/internalization have a small time window of administration, compounds that target intracellular LC activity have a much larger time window of administrations, particularly relevant given the extremely long half-life of the toxin. In recent years, small molecules have been heavily analyzed as potential LC inhibitors based on their increased cellular permeability relative to larger therapeutics (peptides, aptamers, etc.). Lead identification often involves high-throughput screening (HTS), where large libraries of small molecules are screened based on their ability to modulate therapeutic target function. Here we describe a FRET-based assay with a commercial BoNT/A LC substrate and recombinant LC that can be automated for HTS of potential BoNT inhibitors. Moreover, we describe a manual technique that can be used for follow-up secondary screening, or for comparing the potency of several candidate compounds.
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Affiliation(s)
- Dejan Caglič
- Department of Chemistry, The Scripps Research Institute
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7
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Halliwell J, Gwenin C. A label free colorimetric assay for the detection of active botulinum neurotoxin type A by SNAP-25 conjugated colloidal gold. Toxins (Basel) 2013; 5:1381-91. [PMID: 23925142 PMCID: PMC3760041 DOI: 10.3390/toxins5081381] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 07/26/2013] [Accepted: 07/30/2013] [Indexed: 01/09/2023] Open
Abstract
Botulinum neurotoxins are one of the most potent toxins known to man. Current methods of detection involve the quantification of the toxin but do not take into account the percentage of the toxin that is active. At present the assay used for monitoring the activity of the toxin is the mouse bioassay, which is lengthy and has ethical issues due to the use of live animals. This report demonstrates a novel assay that utilises the endopeptidase activity of the toxin to detect Botulinum neurotoxin in a pharmaceutical sample. The cleaving of SNAP-25 is monitored via UV-Visible spectroscopy with a limit of detection of 373 fg/mL and has been further developed into a high throughput method using a microplate reader detecting down to 600 fg/mL of active toxin. The results show clear differences between the toxin product and the placebo, which contains the pharmaceutical excipients human serum albumin and lactose, showing that the assay detects the active form of the toxin.
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Affiliation(s)
| | - Christopher Gwenin
- Author to whom correspondence should be addressed; E-Mail: ; Tel: +44-1248-383-741; Fax: +44-1248-370-528
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8
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Šilhár P, Lardy MA, Hixon MS, Shoemaker CB, Barbieri JT, Struss AK, Lively JM, Javor S, Janda KD. The C-terminus of Botulinum A Protease Has Profound and Unanticipated Kinetic Consequences Upon the Catalytic Cleft. ACS Med Chem Lett 2013; 4:283-287. [PMID: 23565325 DOI: 10.1021/ml300428s] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are among the most deadly poisons known though ironically, they also are of great therapeutic utility. A number of research programs have been initiated to discover small molecule inhibitors of BoNTs metalloprotease activity. Many, though not all of these programs have screened against a truncated and more stable form of the enzyme, that possess comparable catalytic properties to the full length enzyme. Interestingly, several classes of inhibitors notably the hydroxamates, display a large shift in potency between the two enzyme forms. In this report we compare the kinetics of active-site, alpha-exosite and beta-exosite inhibitors versus truncated and full length enzyme. Molecular dynamics simulations conducted with the truncated and homology models of the fully length BoNT LC/A indicate the flexibility of the C-terminus of the full length enzyme is responsible for the potency shifts of active-site proximally binding inhibitors while distal binding (alpha-exosite) inhibitors remain equipotent.
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Affiliation(s)
- Peter Šilhár
- Departments of Chemistry and
Immunology, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey
Pines Road, La Jolla, California 92037, United States
| | - Matthew A. Lardy
- Takeda California Inc., 10410 Science Center Drive, San Diego, California
92121, United States
| | - Mark S. Hixon
- Takeda California Inc., 10410 Science Center Drive, San Diego, California
92121, United States
| | - Charles B. Shoemaker
- Department
of Biomedical Sciences, Tufts Cummings School of Veterinary Medicine, 200 Westboro
Road, North Grafton, Massachusetts 01536, United States
| | - Joseph T. Barbieri
- Department of Microbiology and
Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin 53226, United States
| | - Anjali K. Struss
- Departments of Chemistry and
Immunology, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey
Pines Road, La Jolla, California 92037, United States
| | - Jenny M. Lively
- Departments of Chemistry and
Immunology, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey
Pines Road, La Jolla, California 92037, United States
| | - Sacha Javor
- Departments of Chemistry and
Immunology, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey
Pines Road, La Jolla, California 92037, United States
| | - Kim D. Janda
- Departments of Chemistry and
Immunology, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey
Pines Road, La Jolla, California 92037, United States
- Worm Institute for Research
and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United
States
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9
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Ho M, Goh CH, Brothers MC, Wang S, Young RL, Ou Y, Lui JNM, Kalafatis M, Lan X, Wolf AE, Rienstra CM, Wilson BA. Glycine insertion at protease cleavage site of SNAP25 resists cleavage but enhances affinity for botulinum neurotoxin serotype A. Protein Sci 2012; 21:318-26. [PMID: 22170566 DOI: 10.1002/pro.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The light chain of botulinum neurotoxin A (BoNT/A-LC) is a Zn-dependent protease that specifically cleaves SNAP25 of the SNARE complex, thereby impairing vesicle fusion and neurotransmitter release at neuromuscular junctions. The C-terminus of SNAP25 (residues 141-206) retains full activity for BoNT/A-LC-catalyzed cleavage at P1-P1' (Gln197-Arg198). Using the structure of a complex between the C-terminus of SNAP25 and BoNT/A-LC as a model to design SNAP25-derived pseudosubstrate inhibitors (SNAPIs) that prevent presentation of the scissile bond to the active site, we introduced multiple His residues to replace Ala-Asn-Gln-Arg (residues 195-198) at the substrate cleavage site, with the intent to identify possible side-chain interactions with the active site Zn. We also introduced multiple Gly residues between the P1-P1' residues to explore the spatial tolerance within the active-site cleft. Using a FRET substrate YsCsY, we compared a series of SNAPIs for inhibition of BoNT/A-LC. Among the SNAPIs tested, several known cleavage-resistant, single-point mutants of SNAP25 were poor inhibitors, with most of the mutants losing binding affinity. Replacement with His at the active site did not improve inhibition over wildtype substrate. In contrast, Gly-insertion mutants were not only resistant to cleavage, but also surprisingly showed enhanced affinity for BoNT/A-LC. Two of the Gly-insertion mutants exhibited 10-fold lower IC₅₀ values than the wildtype 66-mer SNAP25 peptide. Our findings illustrate a scenario, where the induced fit between enzyme and bound pseudosubstrate fails to produce the strain and distortion required for catalysis to proceed.
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Affiliation(s)
- Mengfei Ho
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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10
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Singh AK, Stanker LH, Sharma SK. Botulinum neurotoxin: where are we with detection technologies? Crit Rev Microbiol 2012; 39:43-56. [PMID: 22676403 DOI: 10.3109/1040841x.2012.691457] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Because of its high toxicity, botulinum neurotoxin (BoNT) poses a significant risk to humans and it represents a possible biological warfare agent. Nevertheless, BoNT serotypes A and B are considered an effective treatment for a variety of neurological disorders. The growing applicability of BoNT as a drug, and its potential use as a biological threat agent, highlight the urgent need to develop sensitive detection assays and therapeutic counter measures. In the last decade, significant progress has been made in BoNT detection technologies but none have fully replaced the mouse lethality assay, the current "gold standard". Recently, new advances in robotics and the availability of new reagents have allowed development of methods for rapid toxin analysis. These technologies while promising need further refinement.
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Affiliation(s)
- Ajay K Singh
- Food and Drug Administration, Center for Food Safety and Applied Nutrition, College Park, MD 20740, USA
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11
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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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12
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A comparative evaluation of microarray slides as substrates for the development of protease assay biosensors. Exp Mol Pathol 2011; 91:714-7. [DOI: 10.1016/j.yexmp.2011.09.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 09/06/2011] [Indexed: 11/20/2022]
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13
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Depolarization after resonance energy transfer (DARET): A sensitive fluorescence-based assay for botulinum neurotoxin protease activity. Anal Biochem 2011; 413:36-42. [DOI: 10.1016/j.ab.2011.01.043] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 01/28/2011] [Accepted: 01/29/2011] [Indexed: 01/03/2023]
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14
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Ruge DR, Dunning FM, Piazza TM, Molles BE, Adler M, Zeytin FN, Tucker WC. Detection of six serotypes of botulinum neurotoxin using fluorogenic reporters. Anal Biochem 2011; 411:200-9. [PMID: 21216216 DOI: 10.1016/j.ab.2011.01.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 01/03/2011] [Accepted: 01/04/2011] [Indexed: 12/01/2022]
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15
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Ho M, Chang LH, Pires-Alves M, Thyagarajan B, Bloom JE, Gu Z, Aberle KK, Teymorian SA, Bannai Y, Johnson SC, McArdle JJ, Wilson BA. Recombinant botulinum neurotoxin A heavy chain-based delivery vehicles for neuronal cell targeting. Protein Eng Des Sel 2010; 24:247-53. [PMID: 21051321 DOI: 10.1093/protein/gzq093] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The long half-life of botulinum neurotoxin serotype A (BoNT/A) in cells poses a challenge in developing post-exposure therapeutics complementary to existing antitoxin strategies. Delivery vehicles consisting of the toxin heavy chain (HC), including the receptor-binding domain and translocation domain, connected to an inhibitory cargo offer a possible solution for rescuing intoxicated neurons in victims paralyzed from botulism. Here, we report the expression and purification of soluble recombinant prototype green fluorescent protein (GFP) cargo proteins fused to the entire BoNT/A-HC (residues 544-1295) in Escherichia coli with up to a 40 amino acid linker inserted between the cargo and BoNT/A-HC vehicle. We show that these GFP-HC fusion proteins are functionally active and readily taken up by cultured neuronal cells as well as by neuronal cells in mouse motor nerve endings.
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Affiliation(s)
- Mengfei Ho
- Department of Microbiology, University of Illinois at Urbana-Champaign, Champaign, IL, USA
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16
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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.
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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
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Sun S, Francis J, Sapsford KE, Kostov Y, Rasooly A. Multi-wavelength Spatial LED illumination based detector for in vitro detection of Botulinum Neurotoxin A Activity. SENSORS AND ACTUATORS. B, CHEMICAL 2010; 146:297-306. [PMID: 20498728 PMCID: PMC2874159 DOI: 10.1016/j.snb.2010.02.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A portable and rapid detection system for the activity analysis of Botulinum Neurotoxins (BoNT) is needed for food safety and bio-security applications. To improve BoNT activity detection, a previously designed portable charge-coupled device (CCD) based detector was modified and equipped with a higher intensity more versatile multi-wavelength spatial light-emitting diode (LED) illumination, a faster CCD detector and the capability to simultaneously detect 30 samples. A FITC/DABCYL Förster Resonance Energy Transfer (FRET)-labeled peptide substrate (SNAP-25), with BoNT-A target cleavage site sequence was used to measure BoNT-A light chain (LcA) activity through the FITC fluorescence increase that occurs upon peptide substrate cleavage. For fluorescence excitation, a multi-wavelength spatial LED illuminator was used and compared to our previous electroluminescent (EL) strips. The LED illuminator was equipped with blue, green, red and white LEDs, covering a spectrum of 450-680 nm (red 610-650 nm, green 492-550 nm, blue 450-495 nm, and white LED 440-680 nm). In terms of light intensity, the blue LED was found to be ~80 fold higher than the previously used blue EL strips. When measuring the activity of LcA the CCD detector limit of detection (LOD) was found to be 0.08 nM LcA for both the blue LED (2 s exposure) and the blue EL (which require ≥60 s exposure) while the limits of quantitation (LOQ) is about 1 nM. The LOD for white LED was higher at 1.4 nM while the white EL was not used for the assay due to a high variable background. Unlike the weaker intensity EL illumination the high intensity LED illumination enabled shorter exposure times and allowed multi-wavelength illumination without the need to physically change the excitation strip, thus making spectrum excitation of multiple fluorophores possible increasing the versatility of the detector platform for a variety of optical detection assays.
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Affiliation(s)
- Steven Sun
- Division of Biology, Office of Science and Engineering Laboratories, FDA, Silver Spring, MD 20993, USA
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Hakami RM, Ruthel G, Stahl AM, Bavari S. Gaining ground: assays for therapeutics against botulinum neurotoxin. Trends Microbiol 2010; 18:164-72. [DOI: 10.1016/j.tim.2010.02.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 01/20/2010] [Accepted: 02/01/2010] [Indexed: 11/15/2022]
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A single-domain llama antibody potently inhibits the enzymatic activity of botulinum neurotoxin by binding to the non-catalytic alpha-exosite binding region. J Mol Biol 2010; 397:1106-18. [PMID: 20138889 DOI: 10.1016/j.jmb.2010.01.070] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Accepted: 01/27/2010] [Indexed: 02/07/2023]
Abstract
Ingestion or inhalation of botulinum neurotoxin (BoNT) results in botulism, a severe and frequently fatal disease. Current treatments rely on antitoxins, which, while effective, cannot reverse symptoms once BoNT has entered the neuron. For treatments that can reverse intoxication, interest has focused on developing inhibitors of the enzymatic BoNT light chain (BoNT Lc). Such inhibitors typically mimic substrate and bind in or around the substrate cleavage pocket. To explore the full range of binding sites for serotype A light chain (BoNT/A Lc) inhibitors, we created a library of non-immune llama single-domain VHH (camelid heavy-chain variable region derived from heavy-chain-only antibody) antibodies displayed on the surface of the yeast Saccharomyces cerevisiae. Library selection on BoNT/A Lc yielded 15 yeast-displayed VHH with equilibrium dissociation constants (K(d)) from 230 to 0.03 nM measured by flow cytometry. Eight of 15 VHH inhibited the cleavage of substrate SNAP25 (synaptosome-associated protein of 25,000 Da) by BoNT/A Lc. The most potent VHH (Aa1) had a solution K(d) for BoNT/A Lc of 1.47 x 10(-)(10) M and an IC(50) (50% inhibitory concentration) of 4.7 x 10(-)(10) M and was resistant to heat denaturation and reducing conditions. To understand the mechanism by which Aa1 inhibited catalysis, we solved the X-ray crystal structure of the BoNT/A Lc-Aa1 VHH complex at 2.6 A resolution. The structure reveals that the Aa1 VHH binds in the alpha-exosite of the BoNT/A Lc, far from the active site for catalysis. The study validates the utility of non-immune llama VHH libraries as a source of enzyme inhibitors and identifies the BoNT/A Lc alpha-exosite as a target for inhibitor development.
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Abstract
Sensitive and rapid detection of botulinum neurotoxins (BoNTs), the most poisonous substances known to date, is essential for studies of medical applications of BoNTs and detection of poisoned food, as well as for response to potential bioterrorist threats. Currently, the most common method of BoNT detection is the mouse bioassay. While this assay is sensitive, it is slow, quite expensive, has limited throughput and requires sacrificing animals. Herein, we discuss and compare recently developed alternative in vitro detection methods and assess their ability to supplement or replace the mouse bioassay in the analysis of complex matrix samples.
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Affiliation(s)
- Petr Čapek
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA;
| | - Tobin J. Dickerson
- Department of Chemistry and Worm Institute for Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
- Author to whom correspondence should be addressed; ; Tel.: +1-858-784-2522; Fax: +1-858-784-2590
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Čapek P, Dickerson TJ. Sensing the deadliest toxin: technologies for botulinum neurotoxin detection. Toxins (Basel) 2010; 2:24-53. [PMID: 22069545 PMCID: PMC3206617 DOI: 10.3390/toxins2020024] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 12/17/2009] [Accepted: 12/22/2009] [Indexed: 11/16/2022] Open
Abstract
Sensitive and rapid detection of botulinum neurotoxins (BoNTs), the most poisonous substances known to date, is essential for studies of medical applications of BoNTs and detection of poisoned food, as well as for response to potential bioterrorist threats. Currently, the most common method of BoNT detection is the mouse bioassay. While this assay is sensitive, it is slow, quite expensive, has limited throughput and requires sacrificing animals. Herein, we discuss and compare recently developed alternative in vitro detection methods and assess their ability to supplement or replace the mouse bioassay in the analysis of complex matrix samples.
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Affiliation(s)
- Petr Čapek
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA;
| | - Tobin J. Dickerson
- Department of Chemistry and Worm Institute for Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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Potent new small-molecule inhibitor of botulinum neurotoxin serotype A endopeptidase developed by synthesis-based computer-aided molecular design. PLoS One 2009; 4:e7730. [PMID: 19901994 PMCID: PMC2771286 DOI: 10.1371/journal.pone.0007730] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Accepted: 10/13/2009] [Indexed: 11/19/2022] Open
Abstract
Botulinum neurotoxin serotype A (BoNTA) causes a life-threatening neuroparalytic disease known as botulism. Current treatment for post exposure of BoNTA uses antibodies that are effective in neutralizing the extracellular toxin to prevent further intoxication but generally cannot rescue already intoxicated neurons. Effective small-molecule inhibitors of BoNTA endopeptidase (BoNTAe) are desirable because such inhibitors potentially can neutralize the intracellular BoNTA and offer complementary treatment for botulism. Previously we reported a serotype-selective, small-molecule BoNTAe inhibitor with a Kiapp value of 3.8±0.8 µM. This inhibitor was developed by lead identification using virtual screening followed by computer-aided optimization of a lead with an IC50 value of 100 µM. However, it was difficult to further improve the lead from micromolar to even high nanomolar potency due to the unusually large enzyme-substrate interface of BoNTAe. The enzyme-substrate interface area of 4,840 Å2 for BoNTAe is about four times larger than the typical protein-protein interface area of 750–1,500 Å2. Inhibitors must carry several functional groups to block the unusually large interface of BoNTAe, and syntheses of such inhibitors are therefore time-consuming and expensive. Herein we report the development of a serotype-selective, small-molecule, and competitive inhibitor of BoNTAe with a Ki value of 760±170 nM using synthesis-based computer-aided molecular design (SBCAMD). This new approach accounts the practicality and efficiency of inhibitor synthesis in addition to binding affinity and selectivity. We also report a three-dimensional model of BoNTAe in complex with the new inhibitor and the dynamics of the complex predicted by multiple molecular dynamics simulations, and discuss further structural optimization to achieve better in vivo efficacy in neutralizing BoNTA than those of our early micromolar leads. This work provides new insight into structural modification of known small-molecule BoNTAe inhibitors. It also demonstrates that SBCAMD is capable of improving potency of an inhibitor lead by nearly one order of magnitude, even for BoNTAe as one of the most challenging protein targets. The results are insightful for developing effective small-molecule inhibitors of protein targets with large active sites.
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