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Lin L, Olson ME, Sugane T, Turner LD, Tararina MA, Nielsen AL, Kurbanov EK, Pellett S, Johnson EA, Cohen SM, Allen KN, Janda KD. Catch and Anchor Approach To Combat Both Toxicity and Longevity of Botulinum Toxin A. J Med Chem 2020; 63:11100-11120. [PMID: 32886509 PMCID: PMC7581224 DOI: 10.1021/acs.jmedchem.0c01006] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Botulinum neurotoxins have remarkable persistence (∼weeks to months in cells), outlasting the small-molecule inhibitors designed to target them. To address this disconnect, inhibitors bearing two pharmacophores-a zinc binding group and a Cys-reactive warhead-were designed to leverage both affinity and reactivity. A series of first-generation bifunctional inhibitors was achieved through structure-based inhibitor design. Through X-ray crystallography, engagement of both the catalytic Zn2+ and Cys165 was confirmed. A second-generation series improved on affinity by incorporating known reversible inhibitor pharmacophores; the mechanism was confirmed by exhaustive dialysis, mass spectrometry, and in vitro evaluation against the C165S mutant. Finally, a third-generation inhibitor was shown to have good cellular activity and low toxicity. In addition to our findings, an alternative method of modeling time-dependent inhibition that simplifies assay setup and allows comparison of inhibition models is discussed.
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Affiliation(s)
- Lucy Lin
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Margaret E. Olson
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Takashi Sugane
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Lewis D. Turner
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Margarita A. Tararina
- Program in Biomolecular Pharmacology, Boston University School of Medicine, Boston, Massachusetts 02118, United States
| | - Alexander L. Nielsen
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Elbek K. Kurbanov
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Sabine Pellett
- Department of Bacteriology, University of Wisconsin, 1550 Linden Drive, Madison, Wisconsin 53706, United States
| | - Eric A. Johnson
- Department of Bacteriology, University of Wisconsin, 1550 Linden Drive, Madison, Wisconsin 53706, United States
| | - Seth M. Cohen
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Karen N. Allen
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Kim D. Janda
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, Worm Institute of Research and Medicine (WIRM), Scripps Research, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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2
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Lin L, Olson ME, Eubanks LM, Janda KD. Strategies to Counteract Botulinum Neurotoxin A: Nature's Deadliest Biomolecule. Acc Chem Res 2019; 52:2322-2331. [PMID: 31322847 DOI: 10.1021/acs.accounts.9b00261] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Botulinum neurotoxin serotype A (BoNT/A), marketed commercially as Botox, is the most toxic substance known to man with an estimated intravenous lethal dose (LD50) of 1-2 ng/kg in humans. Despite its widespread use in cosmetic and medicinal applications, no postexposure therapeutics are available for the reversal of intoxication in the event of medical malpractice or bioterrorism. Accordingly, the Centers for Disease Control and Prevention categorizes BoNT/A as a Category A pathogen, posing the highest risk to national security and public health as a result of the ease with which BoNT/A can be weaponized and disseminated. BoNT/A-mediated lethality results from neurons impeded from releasing acetylcholine, which ultimately causes muscle paralysis and possible death by asphyxiation with the loss of diaphragm function. Currently, the only available respite for BoNT/A poisoning is antibody-based therapy; however, this intervention is only effective within 12-24 h postexposure. Small molecule therapeutics remain the only opportunity to reverse BoNT/A intoxication after neuronal poisoning and are urgently needed. Nevertheless, no small molecule BoNT/A inhibitors have reached the clinic or even advanced to clinical trials. This Account highlights the accomplishments and existing challenges facing BoNT/A drug discovery today. Using the comprehensive body of work from our laboratory, we illustrate our nearly two-decade endeavor to discover a clinically relevant BoNT/A inhibitor. Specifically, a discussion on the identification and characterization of new chemical leads, the development of in vitro and in vivo assays, and pertinent discoveries in BoNT/A structural biology related to small molecule inhibition is presented. Lead discovery efforts in our laboratory have leveraged both in vitro high-throughput screening and rational design, and an array of mechanistic strategies for inhibiting BoNT/A has been discovered, including noncovalent inhibition, metal-binding active site inhibition, covalent inhibition, and α- and β-exosite inhibition. We contrast the strengths and weaknesses of each of these mechanistic strategies and propose the most favorable approach for success. Finally, we discuss multiple serendipitous discoveries of antibotulism small molecules with alternative mechanisms of action. Remaining challenges facing clinically relevant BoNT/A inhibition are presented and analyzed, including the current inability to reconcile toxin half-life (months to greater than one year) in neurons with in vivo pharmaceutical lifetimes and reoccurring inconsistencies between in vitro, cellular, and in vivo translation. Our Account of BoNT/A chemical research emphasizes the present accomplishments and critically analyzes the remaining obstacles for drug discovery. Importantly, we call for an increased focus on the discovery of safe and effective covalent inhibitors of BoNT/A that compete with the inherent half-life of the toxin.
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Affiliation(s)
- Lucy Lin
- Department of Chemistry, Department of Immunology and Microbial Science, The Skaggs Institute for Chemical Biology, The WIRM Institute for Research & Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Margaret E. Olson
- Department of Chemistry, Department of Immunology and Microbial Science, The Skaggs Institute for Chemical Biology, The WIRM Institute for Research & Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Lisa M. Eubanks
- Department of Chemistry, Department of Immunology and Microbial Science, The Skaggs Institute for Chemical Biology, The WIRM Institute for Research & Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Kim D. Janda
- Department of Chemistry, Department of Immunology and Microbial Science, The Skaggs Institute for Chemical Biology, The WIRM Institute for Research & Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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3
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Chen AY, Adamek RN, Dick BL, Credille CV, Morrison CN, Cohen SM. Targeting Metalloenzymes for Therapeutic Intervention. Chem Rev 2019; 119:1323-1455. [PMID: 30192523 PMCID: PMC6405328 DOI: 10.1021/acs.chemrev.8b00201] [Citation(s) in RCA: 161] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Metalloenzymes are central to a wide range of essential biological activities, including nucleic acid modification, protein degradation, and many others. The role of metalloenzymes in these processes also makes them central for the progression of many diseases and, as such, makes metalloenzymes attractive targets for therapeutic intervention. Increasing awareness of the role metalloenzymes play in disease and their importance as a class of targets has amplified interest in the development of new strategies to develop inhibitors and ultimately useful drugs. In this Review, we provide a broad overview of several drug discovery efforts focused on metalloenzymes and attempt to map out the current landscape of high-value metalloenzyme targets.
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Affiliation(s)
- Allie Y Chen
- Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093 , United States
| | - Rebecca N Adamek
- Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093 , United States
| | - Benjamin L Dick
- Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093 , United States
| | - Cy V Credille
- Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093 , United States
| | - Christine N Morrison
- Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093 , United States
| | - Seth M Cohen
- Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093 , United States
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4
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Xue S, Seki H, Remes M, Šilhár P, Janda K. Examination of α-exosite inhibitors against Botulinum neurotoxin A protease through structure-activity relationship studies of chicoric acid. Bioorg Med Chem Lett 2017; 27:4956-4959. [PMID: 29050781 PMCID: PMC5667901 DOI: 10.1016/j.bmcl.2017.10.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 10/09/2017] [Accepted: 10/10/2017] [Indexed: 12/20/2022]
Abstract
Botulinum neurotoxins (BoNT) are among the most toxic known substances and currently there are no effective treatments for intraneuronal BoNT intoxication. Chicoric acid (ChA) was previously reported as a BoNT/A inhibitor that binds to the enzyme's α-exosite. Herein, we report the synthesis and structure-activity relationships (SARs) of a series of ChA derivatives, which revealed essential binding interactions between ChA and BoNT/A. Moreover, several ChA-based inhibitors with improved potency against the BoNT/A were discovered.
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Affiliation(s)
- Song Xue
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States; Department of Immunology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - Hajime Seki
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States; Department of Immunology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - Marek Remes
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States; Department of Immunology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - Peter Šilhár
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States; Department of Immunology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - Kim Janda
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States; Department of Immunology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States; Worm Institute for Research Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States.
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5
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Bremer PT, Xue S, Janda KD. Picolinic acids as β-exosite inhibitors of botulinum neurotoxin A light chain. Chem Commun (Camb) 2016; 52:12521-12524. [PMID: 27722252 PMCID: PMC5085802 DOI: 10.1039/c6cc06749b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In developing small-molecule inhibitors of botulinum neurotoxin serotype A light chain (BoNT/A LC), substituted picolinic acids were identified. Extensive investigation into the SAR of the picolinic acid scaffold revealed 5-(1-butyl-4-chloro-1H-indol-2-yl)picolinic acid (CBIP), which possessed low micromolar activity against BoNT/A. Kinetic and docking studies demonstrated binding of CBIP to the β-exosite: a largely unexplored site on the LC that holds therapeutic relevance for botulism treatment.
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Affiliation(s)
- Paul T Bremer
- Departments of Chemistry, Immunology and Microbial Sciences, Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA 92037, USA.
| | - Song Xue
- Departments of Chemistry, Immunology and Microbial Sciences, Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA 92037, USA.
| | - Kim D Janda
- Departments of Chemistry, Immunology and Microbial Sciences, Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA 92037, USA.
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6
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Bompiani KM, Caglič D, Krutein MC, Benoni G, Hrones M, Lairson LL, Bian H, Smith GR, Dickerson TJ. High-Throughput Screening Uncovers Novel Botulinum Neurotoxin Inhibitor Chemotypes. ACS COMBINATORIAL SCIENCE 2016; 18:461-74. [PMID: 27314875 DOI: 10.1021/acscombsci.6b00033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Botulism is caused by potent and specific bacterial neurotoxins that infect host neurons and block neurotransmitter release. Treatment for botulism is limited to administration of an antitoxin within a short time window, before the toxin enters neurons. Alternatively, current botulism drug development targets the toxin light chain, which is a zinc-dependent metalloprotease that is delivered into neurons and mediates long-term pathology. Several groups have identified inhibitory small molecules, peptides, or aptamers, although no molecule has advanced to the clinic due to a lack of efficacy in advanced models. Here we used a homogeneous high-throughput enzyme assay to screen three libraries of drug-like small molecules for new chemotypes that modulate recombinant botulinum neurotoxin light chain activity. High-throughput screening of 97088 compounds identified numerous small molecules that activate or inhibit metalloprotease activity. We describe four major classes of inhibitory compounds identified, detail their structure-activity relationships, and assess their relative inhibitory potency. A previously unreported chemotype in any context of enzyme inhibition is described with potent submicromolar inhibition (Ki = 200-300 nM). Additional detailed kinetic analyses and cellular cytotoxicity assays indicate the best compound from this series is a competitive inhibitor with cytotoxicity values around 4-5 μM. Given the potency and drug-like character of these lead compounds, further studies, including cellular activity assays and DMPK analysis, are justified.
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Affiliation(s)
- Kristin M. Bompiani
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Dejan Caglič
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Michelle C. Krutein
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Galit Benoni
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Morgan Hrones
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Luke L. Lairson
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Haiyan Bian
- Fox Chase Chemical Diversity Center, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
| | - Garry R. Smith
- Fox Chase Chemical Diversity Center, 3805 Old Easton Road, Doylestown, Pennsylvania 18902, United States
| | - Tobin J. Dickerson
- Department
of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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Seki H, Xue S, Hixon MS, Pellett S, Remes M, Johnson EA, Janda KD. Toward the discovery of dual inhibitors for botulinum neurotoxin A: concomitant targeting of endocytosis and light chain protease activity. Chem Commun (Camb) 2015; 51:6226-9. [PMID: 25759983 DOI: 10.1039/c5cc00677e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Dyngo-4a™ has been found to be an endocytic inhibitor of BoNT/A neurotoxicity through dynamin inhibition. Herein, we demonstrate this molecule to have a previously unrecognized dual activity against BoNT/A, dynamin-protease inhibition. To establish the importance of this dual activity, detailed kinetic analysis of Dyngo-4a's inhibition of BoNT/A metalloprotease as well as cellular and animal toxicity studies have been described. The research presented is the first polypharmacological approach to counteract BoNT/A intoxication.
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Affiliation(s)
- Hajime Seki
- Departments of Chemistry and Immunology and Microbial Sciences, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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8
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Xue S, Javor S, Hixon MS, Janda KD. Probing BoNT/A protease exosites: implications for inhibitor design and light chain longevity. Biochemistry 2014; 53:6820-4. [PMID: 25295706 PMCID: PMC4222541 DOI: 10.1021/bi500950x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
![]()
Botulinum
neurotoxin serotype A (BoNT/A) is one of the most lethal
toxins known. Its extreme toxicity is due to its light chain (LC),
a zinc protease that cleaves SNAP-25, a synaptosome-associated protein,
leading to the inhibition of neuronal activity. Studies on BoNT/A
LC have revealed that two regions, termed exosites, can play an important
role in BoNT catalytic activity. A clear understanding of how these
exosites influence neurotoxin catalytic activity would provide a critical
framework for deciphering the mechanism of SNAP-25 cleavage and the
design of inhibitors. Herein, based on the crystallographic structure
of BoNT/A LC complexed with its substrate, we designed an α-exosite
binding probe. Experiments with this unique probe demonstrated that
α-exosite binding enhanced both catalytic activity and stability
of the LC. These data help delineate why α-exosite binding is
needed for SNAP-25 cleavage and also provide new insights into the
extended lifetime observed for BoNT/A LC in vivo.
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Affiliation(s)
- Song Xue
- 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
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Bremer PT, Hixon MS, Janda KD. Benzoquinones as inhibitors of botulinum neurotoxin serotype A. Bioorg Med Chem 2014; 22:3971-81. [PMID: 24984937 DOI: 10.1016/j.bmc.2014.06.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 05/31/2014] [Accepted: 06/02/2014] [Indexed: 02/06/2023]
Abstract
Although botulinum neurotoxin serotype A (BoNT/A) is known for its use in cosmetics, it causes a potentially fatal illness, botulism, and can be used as a bioterror weapon. Many compounds have been developed that inhibit the BoNTA zinc-metalloprotease light chain (LC), however, none of these inhibitors have advanced to clinical trials. In this study, a fragment-based approach was implemented to develop novel covalent inhibitors of BoNT/A LC. First, electrophilic fragments were screened against BoNT/A LC, and benzoquinone (BQ) derivatives were found to be active. In kinetic studies, BQ compounds acted as irreversible inhibitors that presumably covalently modify cysteine 165 of BoNT/A LC. Although most BQ derivatives were highly reactive toward glutathione in vitro, a few compounds such as natural product naphthazarin displayed low thiol reactivity and good BoNT/A inhibition. In order to increase the potency of the BQ fragment, computational docking studies were employed to elucidate a scaffold that could bind to sites adjacent to Cys165 while positioning a BQ fragment at Cys165 for covalent modification; 2-amino-N-arylacetamides met these criteria and when linked to BQ displayed at least a 20-fold increase in activity to low μM IC₅₀ values. Unlike BQ alone, the linked-BQ compounds demonstrated only weak irreversible inhibition and therefore acted mainly as non-covalent inhibitors. Further kinetic studies revealed a mutual exclusivity of BQ covalent inactivation and competitive inhibitor binding to sites adjacent to Cys165, refuting the viability of the current strategy for developing more potent irreversible BoNT/A inhibitors. The highlights of this study include the discovery of BQ compounds as irreversible BoNT/A inhibitors and the rational design of low μM IC50 competitive inhibitors that depend on the BQ moiety for activity.
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Affiliation(s)
- Paul T Bremer
- Departments of Chemistry and Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Mark S Hixon
- Discovery Biology, Takeda San Diego, Inc., 10410 Science Center Drive, San Diego, CA 92121, USA
| | - Kim D Janda
- Departments of Chemistry and Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, 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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Seki H, Pellett S, Silhár P, Stowe GN, Blanco B, Lardy MA, Johnson EA, Janda KD. Synthesis/biological evaluation of hydroxamic acids and their prodrugs as inhibitors for Botulinum neurotoxin A light chain. Bioorg Med Chem 2013; 22:1208-17. [PMID: 24360826 DOI: 10.1016/j.bmc.2013.11.053] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 11/28/2013] [Indexed: 01/03/2023]
Abstract
Botulinum neurotoxin A (BoNT/A) is the most potent toxin known. Unfortunately, it is also a potential bioweapon in terrorism, which is without an approved therapeutic treatment once cellular intoxication takes place. Previously, we reported how hydroxamic acid prodrug carbamates increased cellular uptake, which translated to successful inhibition of this neurotoxin. Building upon this research, we detail BoNT/A protease molecular modeling studies accompanied by the construction of small library of hydroxamic acids based on 2,4-dichlorocinnamic hydroxamic acid scaffold and their carbamate prodrug derivatization along with the evaluation of these molecules in both enzymatic and cellular models.
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Affiliation(s)
- Hajime Seki
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - Sabine Pellett
- Department of Bacteriology, University of Wisconsin, 1550 Linden Drive, Madison, WI 53706, United States
| | - Peter Silhár
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - G Neil Stowe
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - Beatriz Blanco
- Centro Singular de Investigación en Química Biológica y Materiales Moleculares (CIQUS), Universidad de Santiago de Compostela, calle Jenaro de la Fuente s/n, 15782 Santiago de Compostela, Spain
| | - Matthew A Lardy
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States
| | - Eric A Johnson
- Department of Bacteriology, University of Wisconsin, 1550 Linden Drive, Madison, WI 53706, United States
| | - Kim D Janda
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States; Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, United States.
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Silhár P, Eubanks LM, Seki H, Pellett S, Javor S, Tepp WH, Johnson EA, Janda KD. Targeting botulinum A cellular toxicity: a prodrug approach. J Med Chem 2013; 56:7870-9. [PMID: 24127873 DOI: 10.1021/jm400873n] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The botulinum neurotoxin light chain (LC) protease has become an important therapeutic target for postexposure treatment of botulism. Hydroxamic acid based small molecules have proven to be potent inhibitors of LC/A with nanomolar Ki values, yet they lack cellular activity conceivably due to low membrane permeability. To overcome this potential liability, we investigated two prodrug strategies, 1,4,2-dioxazole and carbamate, based on our 1-adamantylacetohydroxamic acid scaffold. The 1,4,2-dioxazole prodrug did not demonstrate cellular activity, however, carbamates exhibited cellular potency with the most active compound displaying an EC50 value of 20 μM. Cellular trafficking studies were conducted using a "fluorescently silent" prodrug that remained in this state until cellular uptake was complete, which allowed for visualization of the drug's release inside neuronal cells. In sum, this research sets the stage for future studies leveraging the specific targeting and delivery of these prodrugs, as well as other antibotulinum agents, into neuronal cells.
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Affiliation(s)
- Peter Silhár
- Departments of Chemistry and Immunology and Microbial Science, The Skaggs Institute for Chemical Biology, and The Worm Institute for Research and Medicine, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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13
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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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14
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Šilhár P, Silvaggi NR, Pellett S, Čapková K, Johnson EA, Allen KN, Janda KD. Evaluation of adamantane hydroxamates as botulinum neurotoxin inhibitors: synthesis, crystallography, modeling, kinetic and cellular based studies. Bioorg Med Chem 2012; 21:1344-8. [PMID: 23340139 DOI: 10.1016/j.bmc.2012.12.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 12/01/2012] [Accepted: 12/03/2012] [Indexed: 10/27/2022]
Abstract
Botulinum neurotoxins (BoNTs) are the most lethal biotoxins known to mankind and are responsible for the neuroparalytic disease botulism. Current treatments for botulinum poisoning are all protein based and thus have a limited window of treatment opportunity. Inhibition of the BoNT light chain protease (LC) has emerged as a therapeutic strategy for the treatment of botulism as it may provide an effective post exposure remedy. Using a combination of crystallographic and modeling studies a series of hydroxamates derived from 1-adamantylacetohydroxamic acid (3a) were prepared. From this group of compounds, an improved potency of about 17-fold was observed for two derivatives. Detailed mechanistic studies on these structures revealed a competitive inhibition model, with a K(i)=27 nM, which makes these compounds some of the most potent small molecule, non-peptidic BoNT/A LC inhibitors reported to date.
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Affiliation(s)
- Peter Šilhár
- Department of Chemistry, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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15
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Eichhorn T, Dolimbek BZ, Deeg K, Efferth T, Atassi MZ. Inhibition in vivo of the activity of botulinum neurotoxin A by small molecules selected by virtual screening. Toxicon 2012; 60:1180-90. [PMID: 22960451 DOI: 10.1016/j.toxicon.2012.07.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 07/24/2012] [Accepted: 07/25/2012] [Indexed: 10/28/2022]
Abstract
To search for small molecular size inhibitors of botulinum neurotoxin A (BoNT/A) endopeptidase activity, we have screened the NCI library containing about 1 million structures against the substrate binding pocket of BoNT/A. Virtual screening (VS) was performed with the software Glide (Grid-based ligand docking energetics) and the findings were confirmed by AutoDock. Ten compounds were found that had favorable energetic and glide criteria and 5 of these compounds were selected for their ability to protect mice in vivo against a lethal dose of BoNT/A. Each compound was incubated at different molar excesses with a lethal dose of the toxin and then the mixture injected intravenously into mice. At 4690 M excess, compounds NSC94520 and NSC99639 protected all (100%) the mice from lethal toxicity. Compounds NSC48461 and NSC627733 gave 75% protection. Compound NSC348884 showed the least inhibition of toxicity allowing only a fraction (25%) of the mice to survive challenge with a lethal dose; and in the case of the mice that did not survive there was a considerable delay of mortality. At 2400 M excess compounds NSC94520 remained fully protective while and NSC99639 afforded 75% protection and at 1200 M excess each of these two compounds gave 50% protection. The two compounds gave no protection at 600 or less molar excess. When each compound was administered intravenously at 4690 M excess at different times (from 1 h to 6 h) after the intravenous injection of the active toxin, none of the compounds was able to protect the animals from toxicity. The findings show the value of VS in identifying potential inhibitors of the toxin for further development and improvement.
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Affiliation(s)
- Tolga Eichhorn
- Department of Pharmaceutical Biology, Institute of Pharmacy and Biochemistry, Johannes Gutenberg University, Staudinger Weg 5, 55128 Mainz, Germany
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16
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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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17
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Structure-Based Drug Discovery for Botulinum Neurotoxins. Curr Top Microbiol Immunol 2012; 364:197-218. [DOI: 10.1007/978-3-642-33570-9_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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18
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Čapek P, Zhang Y, Barlow DJ, Houseknecht KL, Smith GR, Dickerson TJ. Enhancing the Pharmacokinetic Properties of Botulinum Neurotoxin Serotype A Protease Inhibitors Through Rational Design. ACS Chem Neurosci 2011; 2:288-293. [PMID: 21743830 DOI: 10.1021/cn200021q] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Botulinum neurotoxin (BoNT), the etiological agent that causes the neuroparalytic disease botulism, has become a highly studied drug target in light of the potential abuse of this toxin as a weapon of bioterrorism. In particular, small molecule inhibitors of the light chain metalloprotease of BoNT serotype A have received significant attention and a number of small molecule and biologic inhibitors have been reported. However, all small molecules reported have been identified from either primary screens or medicinal chemistry follow-up studies, and the pharmacokinetic profiles of these compounds have not been addressed. In this study, we have removed the pharmacologic liabilities of one of the best compounds reported to date, 2,4-dichlorocinnamate hydroxamic acid, and in the process, uncovered a related class of benzothiophene hydroxamic acids that are significantly more potent inhibitors of the BoNT/A light chain, while also possessing greatly improved ADME properties, with the best compound showing the most potent inhibition of BoNT/A light chain reported (K(i) = 77 nM). Using a strategy of incorporating traditional drug development filters early into the discovery process, potential liabilities in BoNT/A lead compounds have been illuminated and removed, clearing the path for advancement into further pharmacologic optimization and in vivo efficacy testing.
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Affiliation(s)
- Petr Čapek
- Department of Chemistry and Worm Institute of Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Yan Zhang
- Fox Chase Chemical Diversity Center, Doylestown, Pennsylvania, United States
| | - Deborah J. Barlow
- Department of Pharmaceutical Sciences, University of New England College of Pharmacy, Portland, Maine, United States
| | - Karen L. Houseknecht
- Department of Pharmaceutical Sciences, University of New England College of Pharmacy, Portland, Maine, United States
| | - Garry R. Smith
- Fox Chase Chemical Diversity Center, Doylestown, Pennsylvania, United States
| | - Tobin J. Dickerson
- Department of Chemistry and Worm Institute of Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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19
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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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20
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Šilhár P, Alakurtti S, Čapková K, Xiaochuan F, Shoemaker CB, Yli-Kauhaluoma J, Janda KD. Synthesis and evaluation of library of betulin derivatives against the botulinum neurotoxin A protease. Bioorg Med Chem Lett 2011; 21:2229-31. [PMID: 21421315 DOI: 10.1016/j.bmcl.2011.02.115] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 02/25/2011] [Accepted: 02/28/2011] [Indexed: 10/18/2022]
Abstract
Botulinum neurotoxins (BoNTs) are the most toxic proteins currently known. Current treatments for botulinum poisoning are all protein based with a limited window of opportunity. Inhibition of the BoNT light chain protease (LC) has emerged as a new therapeutic strategy for the treatment of botulism as it may provide an effective post-exposure remedy. As such, a small library of 40 betulin derivatives was synthesized and screened against the light chain of BoNT serotype A (LC/A); five positive hits (IC(50) <100 μM) were uncovered. Detailed evaluation of inhibition mechanism of three most active compounds revealed a competitive model, with sub-micromolar K(i) value for the best inhibitor (7). Unfortunately, an in vitro cell-based assay did not show any protection of rat cerebellar neurons against BoNT/A intoxication by 7.
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Affiliation(s)
- Peter Šilhár
- Department of Chemistry, Scripps Research Institute, 10550 North Torrey Pines Rd., La Jolla, CA 92037, USA
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21
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Salzameda NT, Eubanks LM, Zakhari JS, Tsuchikama K, DeNunzio NJ, Allen KN, Hixon MS, Janda KD. A cross-over inhibitor of the botulinum neurotoxin light chain B: a natural product implicating an exosite mechanism of action. Chem Commun (Camb) 2011; 47:1713-5. [PMID: 21203627 DOI: 10.1039/c0cc04078a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Clostridium botulinum produces the most lethal toxins known to man, as such they are high risk terrorist threats, and alarmingly there is no approved therapeutic. We report the first cross-over small molecule inhibitor of these neurotoxins and propose a mechanism by which it may impart its inhibitory activity.
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Affiliation(s)
- Nicholas T Salzameda
- Department of Chemistry, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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22
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Eubanks LM, Šilhár P, Salzameda NT, Zakhari JS, Xiaochuan F, Barbieri JT, Shoemaker CB, Hixon MS, Janda KD. Identification of a Natural Product Antagonist against the Botulinum Neurotoxin Light Chain Protease. ACS Med Chem Lett 2010; 1:268-272. [PMID: 20959871 DOI: 10.1021/ml100074s] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are the etiological agents responsible for botulism, a disease characterized by peripheral neuromuscular blockade and a characteristic flaccid paralysis of humans. BoNTs are the most lethal known poisons affecting humans and has been recognized as a potential bioterrorist threat. Current treatments for botulinum poisoning are predominately prophylactic in nature relying on passive immunization with antitoxins. Inhibition of the BoNT light chain metalloprotease (LC) has emerged as a new therapeutic strategy for the treatment of botulism that may provide an effective post-exposure remedy. A high-throughput screening effort against the light chain of BoNT serotype A (LC/A) was conducted with the John Hopkins Clinical Compound Library comprised of over 1,500 existing drugs. Lomofungin, a natural product first isolated in the late 1960's, was identified as an inhibitor of LC/A, displaying classical noncompetitive inhibition kinetics with a K(i) of 6.7 ± 0.7 µM. Inhibitor combination studies reveal that lomofungin binding is nonmutually exclusive (synergistic). The inhibition profile of lomofungin has been delineated by the use of both an active site inhibitor, 2,4-dichlorocinnamic hydroxamate, and a noncompetitive inhibitor d-chicoric acid; the mechanistic implications of these observations are discussed. Lastly, cellular efficacy was investigated using a rat primary cell model which demonstrated that lomofungin can protect against SNAP-25 cleavage, the intracellular protein target of LC/A.
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Affiliation(s)
- Lisa M. Eubanks
- Departments of Chemistry and Immunology
- The Skaggs Institute for Chemical Biology
- The Worm Institute for Research and Medicine
| | - Peter Šilhár
- Departments of Chemistry and Immunology
- The Skaggs Institute for Chemical Biology
| | | | - Joseph S. Zakhari
- Departments of Chemistry and Immunology
- The Skaggs Institute for Chemical Biology
| | - Feng Xiaochuan
- Department of Biomedical Sciences, Tufts Cummings School of Veterinary Medicine, 200 Westboro Road, North Grafton, Massachusetts 01536
| | - Joseph T. Barbieri
- Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin 53226
| | - Charles B. Shoemaker
- Department of Biomedical Sciences, Tufts Cummings School of Veterinary Medicine, 200 Westboro Road, North Grafton, Massachusetts 01536
| | - Mark S. Hixon
- Departments of Chemistry and Immunology
- The Skaggs Institute for Chemical Biology
- The Worm Institute for Research and Medicine
| | - Kim D. Janda
- Departments of Chemistry and Immunology
- The Skaggs Institute for Chemical Biology
- The Worm Institute for Research and Medicine
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23
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Thyagarajan B, Potian JG, Garcia CC, Hognason K, Čapková K, Moe ST, Jacobson AR, Janda KD, McArdle JJ. Effects of hydroxamate metalloendoprotease inhibitors on botulinum neurotoxin A poisoned mouse neuromuscular junctions. Neuropharmacology 2010; 58:1189-98. [PMID: 20211192 PMCID: PMC2867082 DOI: 10.1016/j.neuropharm.2010.02.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Accepted: 02/17/2010] [Indexed: 11/16/2022]
Abstract
Currently the only therapy for botulinum neurotoxin A (BoNT/A) poisoning is antitoxin. Antidotes that are effective after BoNT/A has entered the motor nerve terminals would dramatically benefit BoNT/A therapy. Inhibition of proteolytic activity of BoNT/A light chain by metalloendoprotease inhibitors (MEIs) is under development. We tested the effects of MEIs on in vitro as well as in vivo BoNT/A poisoned mouse nerve-muscle preparations (NMPs). The K(i) for inhibition of BoNT/A metalloendoprotease was 0.40 and 0.36 muM, respectively, for 2,4-dichlorocinnamic acid hydroxamate (DCH) and its methyl derivative, ABS 130. Acute treatment of nerve-muscle preparations with 10 pM BoNT/A inhibited nerve-evoked muscle twitches, reduced mean quantal content, and induced failures of endplate currents (EPCs). Bath application of 10 muM DCH or 5 muM ABS 130 reduced failures, increased the quantal content of EPCs, and partially restored muscle twitches after a delay of 40-90 min. The restorative effects of DCH and ABS 130, as well as 3,4 diaminopyridine (DAP) on twitch tension were greater at 22 degrees C compared to 37 degrees C. Unlike DAP, neither DCH nor ABS 130 increased Ca(2+) levels in cholinergic Neuro 2a cells. Injection of MEIs into mouse hind limbs before or after BoNT/A injection neither prevented the toe spread reflex inhibition nor improved muscle functions. We suggest that hydroxamate MEIs partially restore neurotransmission of acutely BoNT/A poisoned nerve-muscle preparations in vitro in a temperature dependent manner without increasing the Ca(2+) levels within motor nerve endings.
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Affiliation(s)
- Baskaran Thyagarajan
- Department of Pharmacology and Physiology, UMDNJ – New Jersey Medical School, Newark, NJ 07103
| | - Joseph G. Potian
- Department of Pharmacology and Physiology, UMDNJ – New Jersey Medical School, Newark, NJ 07103
| | - Carmen C. Garcia
- Department of Pharmacology and Physiology, UMDNJ – New Jersey Medical School, Newark, NJ 07103
| | - Kormakur Hognason
- Department of Pharmacology and Physiology, UMDNJ – New Jersey Medical School, Newark, NJ 07103
| | - Kateřina Čapková
- Department of Chemistry, The Skaggs Institute for Chemical Biology and the Worm Institute of Research and Medicine (WIRM), The Scripps Research Institute, La Jolla, CA 92037
| | | | | | - Kim D. Janda
- Department of Chemistry, The Skaggs Institute for Chemical Biology and the Worm Institute of Research and Medicine (WIRM), The Scripps Research Institute, La Jolla, CA 92037
| | - Joseph J. McArdle
- Department of Pharmacology and Physiology, UMDNJ – New Jersey Medical School, Newark, NJ 07103
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24
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Burnett JC, Li B, Pai R, Cardinale SC, Butler MM, Peet NP, Moir D, Bavari S, Bowlin T. Analysis of Botulinum Neurotoxin Serotype A Metalloprotease Inhibitors: Analogs of a Chemotype for Therapeutic Development in the Context of a Three-Zone Pharmacophore. OPEN ACCESS BIOINFORMATICS 2010; 2010:11-18. [PMID: 21103387 PMCID: PMC2983112 DOI: 10.2147/oab.s7251] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Botulinum neurotoxins (BoNTs), and in particular serotype A, are the most poisonous of known biological substances, and are responsible for the flaccid paralysis of the disease state botulism. Because of the extreme toxicity of these enzymes, BoNTs are considered highest priority biothreat agents. To counter BoNT serotype A (BoNT/A) poisoning, the discovery and development of small molecule, drug-like inhibitors as post-intoxication therapeutic agents has been/is being pursued. Specifically, we are focusing on inhibitors of the BoNT/A light chain (LC) (ie, a metalloprotease) subunit, since such compounds can enter neurons and provide post-intoxication protection of the enzyme target substrate. To aid/facilitate this drug development effort, a pharmacophore for inhibition of the BoNT/A LC subunit was previously developed, and is continually being refined via the incorporation of novel and diverse inhibitor chemotypes. Here, we describe several analogs of a promising therapeutic chemotype in the context of the pharmacophore for BoNT/A LC inhibition. Specifically, we describe: 1) the pharmacophoric 'fits' of the analogs and how these 'fits' rationalize the in vitro inhibitory potencies of the analogs and 2) pharmacophore refinement via the inclusion of new components from the most potent of the presented analogs.
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Affiliation(s)
- James C. Burnett
- Target, Structure-Based Drug Discovery Group, SAIC-Frederick, Inc., National Cancer Institute at Frederick, Frederick, MD 21702 (USA)
| | - Bing Li
- Microbiotix, Inc., Worcester, MA 01605 (USA)
| | - Ramdas Pai
- Microbiotix, Inc., Worcester, MA 01605 (USA)
| | | | | | | | - Donald Moir
- Microbiotix, Inc., Worcester, MA 01605 (USA)
| | - Sina Bavari
- Division of Integrated Toxicology, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702 (USA)
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25
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Stowe GN, Silhár P, Hixon MS, Silvaggi NR, Allen KN, Moe ST, Jacobson AR, Barbieri JT, Janda KD. Chirality holds the key for potent inhibition of the botulinum neurotoxin serotype a protease. Org Lett 2010; 12:756-9. [PMID: 20092262 DOI: 10.1021/ol902820z] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Botulinum neurotoxin serotype A (BoNT/A) is the most toxic protein known to man and also a bioterrorism agent. As defined by our previous research targeting the etiological agent responsible for BoNT/A intoxication, a protease, we now report on the asymmetric synthesis of four new BoNT/A inhibitors; the most potent of this series is roughly 2-fold more active than the best small molecule inhibitor currently known.
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Affiliation(s)
- G Neil Stowe
- Department of Chemistry, The Skaggs Institute for Chemical Biology and Worm Institute of Research and Medicine (WIRM), The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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26
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Šilhár P, Čapková K, Salzameda NT, Barbieri JT, Hixon MS, Janda KD. Botulinum neurotoxin A protease: discovery of natural product exosite inhibitors. J Am Chem Soc 2010; 132:2868-9. [PMID: 20158239 PMCID: PMC2832098 DOI: 10.1021/ja910761y] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new mechanistic class of BoNT/A zinc metalloprotease inhibitors, from Echinacea, exemplified by the natural product d-chicoric acid (I1) is disclosed. A detailed evaluation of chicoric acid's mechanism of inhibition reveals that the inhibitor binds to an exosite, displays noncompetitive partial inhibition, and is synergistic with a competitive active site inhibitor when used in combination. Other components found in Echinacea, I3 and I4, were also inhibitors of the protease.
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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 Rd, La Jolla, CA, 92037, USA
| | - Kateřina Čapková
- Departments of Chemistry and Immunology, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - Nicholas T. Salzameda
- Departments of Chemistry and Immunology, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd, La Jolla, CA, 92037, USA
| | - Joseph T. Barbieri
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Rd, Milwaukee, WI 53226
| | - Mark S. Hixon
- Discovery Biology, Takeda San Diego, Inc., San Diego CA, 10410 Science Center Dr, San Diego, CA 92121, USA
| | - Kim D. Janda
- Departments of Chemistry and Immunology, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd, La Jolla, CA, 92037, USA
- Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute,10550 North Torrey Pines Rd, La Jolla, CA 92037
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27
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Capková K, Hixon MS, Pellett S, Barbieri JT, Johnson EA, Janda KD. Benzylidene cyclopentenediones: First irreversible inhibitors against botulinum neurotoxin A's zinc endopeptidase. Bioorg Med Chem Lett 2009; 20:206-8. [PMID: 19914829 DOI: 10.1016/j.bmcl.2009.10.129] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Accepted: 10/29/2009] [Indexed: 11/30/2022]
Abstract
A series of benzylidene cyclopentenedione-based inhibitors, acting through covalent modification of the active site of botulinum neurotoxin A light chain metalloprotease, are reported.
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Affiliation(s)
- Katerina Capková
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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28
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Salzameda NT, Barbieri JT, Janda KD. Synthetic substrate for application in both high and low throughput assays for botulinum neurotoxin B protease inhibitors. Bioorg Med Chem Lett 2009; 19:5848-50. [PMID: 19747823 DOI: 10.1016/j.bmcl.2009.08.079] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 08/20/2009] [Accepted: 08/24/2009] [Indexed: 10/20/2022]
Abstract
A FRET peptide substrate was synthesized and evaluated for enzymatic cleavage by the BoNT/B light chain protease. The FRET substrate was found to be useful in both a high throughput assay to uncover initial 'hits' and a low throughput HPLC assay to determine kinetic parameters and modes of inhibition.
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Affiliation(s)
- Nicholas T Salzameda
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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29
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Capková K, Salzameda NT, Janda KD. Investigations into small molecule non-peptidic inhibitors of the botulinum neurotoxins. Toxicon 2009; 54:575-82. [PMID: 19327377 DOI: 10.1016/j.toxicon.2009.03.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 03/03/2009] [Accepted: 03/03/2009] [Indexed: 11/18/2022]
Abstract
Botulinum neurotoxins (BoNTs), proteins secreted by the bacteria genus Clostridium, represent a group of extremely lethal toxins and a potential bioterrorism threat. As the current therapeutic options are of a predominantly prophylactic nature and cannot be used en masse, new strategies and ultimately potential treatments are desperately needed to combat any widespread release of these neurotoxins. In these regards, our laboratory has been working on developing new alternatives to treat botulinum intoxication through the development of inhibitors of the light chain proteases, the etiological agent which causes BoNT intoxication. Such a strategy has required the construction of two high-throughput screens and small molecule non-peptidic libraries; excitingly, inhibitors of the BoNT/A protease have been uncovered and are being optimized via structure activity relationship studies.
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Affiliation(s)
- Katerina Capková
- Departments of Chemistry and Immunology, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA
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