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Li B, Pai R, Cardinale SC, Butler MM, Peet NP, Moir DT, Bavari S, Bowlin TL. Synthesis and biological evaluation of botulinum neurotoxin a protease inhibitors. J Med Chem 2010; 53:2264-76. [PMID: 20155918 DOI: 10.1021/jm901852f] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
NSC 240898 was previously identified as a botulinum neurotoxin A light chain (BoNT/A LC) endopeptidase inhibitor by screening the National Cancer Institute Open Repository diversity set. Two types of analogues have been synthesized and shown to inhibit BoNT/A LC in a FRET-based enzyme assay, with confirmation in an HPLC-based assay. These two series of compounds have also been evaluated for inhibition of anthrax lethal factor (LF), an unrelated metalloprotease, to examine enzyme specificity of the BoNT/A LC inhibition. The most potent inhibitor against BoNT/A LC in these two series is compound 12 (IC(50) = 2.5 microM, FRET assay), which is 4.4-fold more potent than the lead structure and 11.2-fold more selective for BoNT/A LC versus the anthrax LF metalloproteinase. Structure-activity relationship studies have revealed structural features important to potency and enzyme specificity.
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Affiliation(s)
- Bing Li
- Microbiotix Inc, One Innovation Drive, Worcester, Massachusetts 01605, USA.
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52
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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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53
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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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54
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Freedman RA, Winer EP. Adjuvant therapy for postmenopausal women with endocrine-sensitive breast cancer. Breast 2010; 19:69-75. [PMID: 20034796 DOI: 10.1016/j.breast.2009.11.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 10/02/2009] [Accepted: 11/26/2009] [Indexed: 11/30/2022] Open
Abstract
Approximately 180,000 women are diagnosed with breast cancer in the United States annually. The majority of these women are postmenopausal and have endocrine-sensitive tumors. Over the last four decades, multiple clinical trials have been conducted in efforts to establish and advance adjuvant endocrine therapies. We review the available evidence for adjuvant endocrine therapies and current recommendations for therapy in postmenopausal women. Although we have made substantial progress in the treatment of endocrine-sensitive breast cancer, future study will require incorporation of biological and translational questions with the goal of enhancing treatment benefits and minimizing toxicity.
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Affiliation(s)
- Rachel A Freedman
- Harvard Medical School, Dana Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA.
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55
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Roselin LS, Lin MS, Lin PH, Chang Y, Chen WY. Recent trends and some applications of isothermal titration calorimetry in biotechnology. Biotechnol J 2010; 5:85-98. [DOI: 10.1002/biot.200900092] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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56
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Cai S, Lindo P, Park JB, Vasa K, Singh BR. The identification and biochemical characterization of drug-like compounds that inhibit botulinum neurotoxin serotype A endopeptidase activity. Toxicon 2009; 55:818-26. [PMID: 20003913 DOI: 10.1016/j.toxicon.2009.11.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2009] [Revised: 10/17/2009] [Accepted: 11/17/2009] [Indexed: 10/20/2022]
Abstract
A robust, high-throughput, two-tiered assay for screening small molecule inhibitors against botulinum neurotoxin serotype A was developed and employed to screen 16,544 compounds. Thirty-four compounds were identified as potent hits employing the first-tier assay. Subsequently, nine were confirmed as actives by our second-tier confirmatory assay. Of these, one displayed potent inhibitory efficacy, possessing an IC(50)=16 microM (+/-1.6 microM) in our in vitro assay. This inhibitor (0831-1035) is highly water-soluble, and possesses an IC(50)=47 microM (+/-7.0 microM) in our primary cell culture assay (with virtually no cytotoxicity up to 500 microM), suggesting that this inhibitor is a good candidate for further development as a therapeutic countermeasure to treat botulism resulting from botulinum neurotoxin serotype A intoxication. An enzyme kinetics study indicated that this inhibitor exhibits mixed non-competitive inhibition, with a K(I)=9 microM.
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Affiliation(s)
- Shuowei Cai
- Botulinum Research Center, and Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA
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57
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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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58
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Toth SI, Smith LA, Ahmed SA. Extreme sensitivity of botulinum neurotoxin domains towards mild agitation. J Pharm Sci 2009; 98:3302-11. [PMID: 19226630 DOI: 10.1002/jps.21676] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Botulinum neurotoxins (BoNTs) and their fragments are targets of therapeutic developments and are increasingly used as therapeutic, prophylactic, and research reagents. However, published data on their properties vary widely. In order to gain a better understanding of these variations, we initiated a systematic investigation of the stability parameters of catalytic light chains (Lc) as well as of cell surface binding domains (Hc) of the neurotoxin. When followed by CD spectroscopy, we noticed that the recombinant light chains of serotypes A (LcA), B, D, E, and G rapidly lost their secondary structures by mild stirring. Denaturation of LcA increased with stirring speed and temperature resulting in a catalytically inactive precipitate. Reducing agents or an anaerobic environment were ineffective in the denaturation. Under identical conditions, bovine serum albumin, ovalbumin, carboxypeptidase B, and of thermolysin, a structural and functional analogue of LcA, remained unchanged. Hc domains of serotype A, B, C, E, and F were also denatured by mild stirring. Adding the nonionic detergent Tween-20 to LcA completely prevented the denaturation. We speculate that the BoNT domains undergo surface denaturation due to rapid exposure of hydrophobic residues by mechanical agitation. This study has important implications for handling BoNT proteins used in therapeutic development.
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Affiliation(s)
- Stephen I Toth
- Department Molecular Biology, Integrated Toxicology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland 21702, USA
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59
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Yu R, Wang S, Yu YZ, Du WS, Yang F, Yu WY, Sun ZW. Neutralizing antibodies of botulinum neurotoxin serotype A screened from a fully synthetic human antibody phage display library. ACTA ACUST UNITED AC 2009; 14:991-8. [PMID: 19726786 DOI: 10.1177/1087057109343206] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The botulinum neurotoxins (BoNTs) produced by Clostridium botulinum are the most poisonous protein substances known. The neutralizing antibodies against botulinum neurotoxin can effectively prevent and cure the toxicosis. Using purified Hc fragments of botulinum neurotoxin serotype A (BoNT/A-Hc) as antigen, 2 specific neutralizing antibodies mapping different epitopes were selected from a fully synthetic human antibody library. The 2 antibodies can effectively inhibit the binding between BoNT/A-Hc and differentiated PC-12 cells in vitro, and the neutralization was evaluated in vivo. Although no single mAb completely protected mice from toxin, they both could prolong time to death when challenged with 20 LD(50)s (50% lethal doses) of BoNT/A. When used together, the mAbs completely neutralized 1000 LD(50)s/mg Ab, suggesting their high neutralizing potency in vivo. The results would lead to further production of neutralizing antibody drugs against BoNT/A. It also proved that it was a quick method to obtain human therapeutic antibodies by selecting from the fully synthetic human antibody phage display library.
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Affiliation(s)
- Rui Yu
- Beijing Institute of Biotechnology, Beijing, China
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60
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Identification and biochemical characterization of small-molecule inhibitors of Clostridium botulinum neurotoxin serotype A. Antimicrob Agents Chemother 2009; 53:3478-86. [PMID: 19528275 DOI: 10.1128/aac.00141-09] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An integrated strategy that combined in silico screening and tiered biochemical assays (enzymatic, in vitro, and ex vivo) was used to identify and characterize effective small-molecule inhibitors of Clostridium botulinum neurotoxin serotype A (BoNT/A). Virtual screening was initially performed by computationally docking compounds of the National Cancer Institute (NCI) database into the active site of BoNT/A light chain (LC). A total of 100 high-scoring compounds were evaluated in a high-performance liquid chromatography (HPLC)-based protease assay using recombinant full-length BoNT/A LC. Seven compounds that significantly inhibited the BoNT/A protease activity were selected. Database search queries of the best candidate hit [7-((4-nitro-anilino)(phenyl)methyl)-8-quinolinol (NSC 1010)] were performed to mine its nontoxic analogs. Fifty-five analogs of NSC 1010 were synthesized and examined by the HPLC-based assay. Of these, five quinolinol derivatives that potently inhibited both full-length BoNT/A LC and truncated BoNT/A LC (residues 1 to 425) were selected for further inhibition studies in neuroblastoma (N2a) cell-based and tissue-based mouse phrenic nerve hemidiaphragm assays. Consistent with enzymatic assays, in vitro and ex vivo studies revealed that these five quinolinol-based analogs effectively neutralized BoNT/A toxicity, with CB 7969312 exhibiting ex vivo protection at 0.5 microM. To date, this is the most potent BoNT/A small-molecule inhibitor that showed activity in an ex vivo assay. The reduced toxicity and high potency demonstrated by these five compounds at the biochemical, cellular, and tissue levels are distinctive among the BoNT/A small-molecule inhibitors reported thus far. This study demonstrates the utility of a multidisciplinary approach (in silico screening coupled with biochemical testing) for identifying promising small-molecule BoNT/A inhibitors.
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61
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Larsen JC. U.S. Army Botulinum Neurotoxin (BoNT) Medical Therapeutics Research Program: past accomplishments and future directions. Drug Dev Res 2009. [DOI: 10.1002/ddr.20304] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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62
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Brunger AT, Rummel A. Receptor and substrate interactions of clostridial neurotoxins. Toxicon 2009; 54:550-60. [PMID: 19268493 PMCID: PMC2756235 DOI: 10.1016/j.toxicon.2008.12.027] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 12/01/2008] [Accepted: 12/02/2008] [Indexed: 01/27/2023]
Abstract
The high potency of clostridial neurotoxins relies predominantly on their neurospecific binding and specific hydrolysis of SNARE proteins. Their multi-step mode of mechanism can be ascribed to their multi-domain three-dimensional structure. The C-terminal H(CC)-domain interacts subsequently with complex polysialo-gangliosides such as GT1b and a synaptic vesicle protein receptor via two neighbouring binding sites, resulting in highly specific uptake of the neurotoxins at synapses of cholinergic motoneurons. After its translocation the enzymatically active light chain specifically hydrolyses specific SNARE proteins, preventing SNARE complex assembly and thereby blocking exocytosis of neurotransmitter.
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Affiliation(s)
- Axel T Brunger
- The Howard Hughes Medical Institute and Departments of Molecular and Cellular Physiology, Neurology and Neurological Sciences, Structural Biology, and Photon Science, Stanford University, J.H. Clark Center, E300C, 318 Campus Drive, Stanford, CA 94305, USA.
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63
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Pharmacophore-guided lead optimization: the rational design of a non-zinc coordinating, sub-micromolar inhibitor of the botulinum neurotoxin serotype a metalloprotease. Bioorg Med Chem Lett 2009; 19:5811-3. [PMID: 19703771 DOI: 10.1016/j.bmcl.2009.01.111] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Accepted: 01/07/2009] [Indexed: 11/22/2022]
Abstract
Botulinum neurotoxins, responsible for the neuroparalytic syndrome botulism, are the deadliest of known biological toxins. The work described in this study was based on a three-zone pharmacophore model for botulinum neurotoxin serotype A light chain inhibition. Specifically, the pharmacophore defined a separation between the overlaps of several different, non-zinc(II)-coordinating small molecule chemotypes, enabling the design and synthesis of a new structural hybrid possessing a Ki=600 nM (+/-100 nM).
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64
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Hermone AR, Burnett JC, Nuss JE, Tressler LE, Nguyen TL, Solaja BA, Vennerstrom JL, Schmidt JJ, Wipf P, Bavari S, Gussio R. Three-dimensional database mining identifies a unique chemotype that unites structurally diverse botulinum neurotoxin serotype A inhibitors in a three-zone pharmacophore. ChemMedChem 2009; 3:1905-12. [PMID: 19006141 DOI: 10.1002/cmdc.200800241] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A search query consisting of two aromatic centers and two cationic centers was defined based on previously identified small molecule inhibitors of the botulinum neurotoxin serotype A light chain (BoNT/A LC) and used to mine the National Cancer Institute Open Repository. Ten small molecule hits were identified, and upon testing, three demonstrated inhibitory activity. Of these, one was structurally unique, possessing a rigid diazachrysene scaffold. The steric limitations of the diazachrysene imposed a separation between the overlaps of previously identified inhibitors, revealing an extended binding mode. As a result, the pharmacophore for BoNT/A LC inhibition has been modified to encompass three zones. To demonstrate the utility of this model, a novel three-zone inhibitor was mined and its activity was confirmed.
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Affiliation(s)
- Ann R Hermone
- Target Structure-Based Drug Discovery Group, SAIC-Frederick, Inc. National Cancer Institute at Frederick, P.O. Box B, Frederick, MD 21702, USA
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65
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Wipf P, Wang C, Widom J, Petronijevic F, C. Burnett J, E. Nuss J, Bavari S, Gussio R. Synthesis and Biological Evaluation of Inhibitors of Botulinum Neurotoxin Metalloprotease. HETEROCYCLES 2009. [DOI: 10.3987/com-08-s(d)8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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66
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Willis B, Eubanks LM, Dickerson TJ, Janda KD. The strange case of the botulinum neurotoxin: using chemistry and biology to modulate the most deadly poison. Angew Chem Int Ed Engl 2008; 47:8360-79. [PMID: 18844202 DOI: 10.1002/anie.200705531] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the classic novella "The Strange Case of Dr. Jekyll and Mr. Hyde", Robert Louis Stevenson paints a stark picture of the duality of good and evil within a single man. Botulinum neurotoxin (BoNT), the most potent known toxin, possesses an analogous dichotomous nature: It shows a pronounced morbidity and mortality, but it is used with great effect in much lower doses in a wide range of clinical scenarios. Recently, tremendous strides have been made in the basic understanding of the structure and function of BoNT, which have translated into widespread efforts towards the discovery of biomacromolecules and small molecules that specifically modulate BoNT activity. Particular emphasis has been placed on the identification of inhibitors that can counteract BoNT exposure in the event of a bioterrorist attack. This Review summarizes the current advances in the development of therapeutics, including vaccines, peptides, and small-molecule inhibitors, for the prevention and treatment of botulism.
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Affiliation(s)
- Bert Willis
- Department of Chemistry, Skaggs Institute for Chemical Biology, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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67
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Bjelić S, Jelesarov I. A survey of the year 2007 literature on applications of isothermal titration calorimetry. J Mol Recognit 2008; 21:289-312. [PMID: 18729242 DOI: 10.1002/jmr.909] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Elucidation of the energetic principles of binding affinity and specificity is a central task in many branches of current sciences: biology, medicine, pharmacology, chemistry, material sciences, etc. In biomedical research, integral approaches combining structural information with in-solution biophysical data have proved to be a powerful way toward understanding the physical basis of vital cellular phenomena. Isothermal titration calorimetry (ITC) is a valuable experimental tool facilitating quantification of the thermodynamic parameters that characterize recognition processes involving biomacromolecules. The method provides access to all relevant thermodynamic information by performing a few experiments. In particular, ITC experiments allow to by-pass tedious and (rarely precise) procedures aimed at determining the changes in enthalpy and entropy upon binding by van't Hoff analysis. Notwithstanding limitations, ITC has now the reputation of being the "gold standard" and ITC data are widely used to validate theoretical predictions of thermodynamic parameters, as well as to benchmark the results of novel binding assays. In this paper, we discuss several publications from 2007 reporting ITC results. The focus is on applications in biologically oriented fields. We do not intend a comprehensive coverage of all newly accumulated information. Rather, we emphasize work which has captured our attention with originality and far-reaching analysis, or else has provided ideas for expanding the potential of the method.
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Affiliation(s)
- Sasa Bjelić
- Biochemisches Institut der Universität Zürich, Winterthurerstrasse 190, Zürich, Switzerland
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68
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Willis B, Eubanks L, Dickerson T, Janda K. Der seltsame Fall des Botulinum-Neurotoxins: chemische und biologische Modulierung des tödlichsten aller Gifte. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200705531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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69
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Zuniga JE, Schmidt JJ, Fenn T, Burnett JC, Araç D, Gussio R, Stafford RG, Badie SS, Bavari S, Brunger AT. A potent peptidomimetic inhibitor of botulinum neurotoxin serotype A has a very different conformation than SNAP-25 substrate. Structure 2008; 16:1588-97. [PMID: 18940613 PMCID: PMC2716802 DOI: 10.1016/j.str.2008.07.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 07/11/2008] [Accepted: 07/13/2008] [Indexed: 01/07/2023]
Abstract
Botulinum neurotoxin serotype A is the most lethal of all known toxins. Here, we report the crystal structure, along with SAR data, of the zinc metalloprotease domain of BoNT/A bound to a potent peptidomimetic inhibitor (K(i)=41 nM) that resembles the local sequence of the SNAP-25 substrate. Surprisingly, the inhibitor adopts a helical conformation around the cleavage site, in contrast to the extended conformation of the native substrate. The backbone of the inhibitor's P1 residue displaces the putative catalytic water molecule and concomitantly interacts with the "proton shuttle" E224. This mechanism of inhibition is aided by residue contacts in the conserved S1' pocket of the substrate binding cleft and by the induction of new hydrophobic pockets, which are not present in the apo form, especially for the P2' residue of the inhibitor. Our inhibitor is specific for BoNT/A as it does not inhibit other BoNT serotypes or thermolysin.
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Affiliation(s)
- Jorge E. Zuniga
- Howard Hughes Medical Institute, and Departments of Molecular and Cellular Physiology, Neurology and Neurological Science, Structural Biology, and Photon Science, Stanford University, Stanford, CA 94305, USA
| | - James J. Schmidt
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland 21702
| | - Timothy Fenn
- Howard Hughes Medical Institute, and Departments of Molecular and Cellular Physiology, Neurology and Neurological Science, Structural Biology, and Photon Science, Stanford University, Stanford, CA 94305, USA
| | - James C. Burnett
- Target Structure-based Drug Discovery Group, SAIC-Frederick, Inc., National Cancer Institute, Frederick, Maryland 21702
| | - Demet Araç
- Howard Hughes Medical Institute, and Departments of Molecular and Cellular Physiology, Neurology and Neurological Science, Structural Biology, and Photon Science, Stanford University, Stanford, CA 94305, USA
| | - Rick Gussio
- Developmental Therapeutics Program, National Cancer Institute, Frederick, Maryland 21702
| | - Robert G. Stafford
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland 21702
| | - Shirin S. Badie
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland 21702
| | - Sina Bavari
- United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland 21702
| | - Axel T. Brunger
- Howard Hughes Medical Institute, and Departments of Molecular and Cellular Physiology, Neurology and Neurological Science, Structural Biology, and Photon Science, Stanford University, Stanford, CA 94305, USA,Corresponding author: , Phone number: 650-736-1031, Fax number: 650-736-1961
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70
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Substrate binding mode and its implication on drug design for botulinum neurotoxin A. PLoS Pathog 2008; 4:e1000165. [PMID: 18818739 PMCID: PMC2533696 DOI: 10.1371/journal.ppat.1000165] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Accepted: 08/28/2008] [Indexed: 11/19/2022] Open
Abstract
The seven antigenically distinct serotypes of Clostridium botulinum neurotoxins, the causative agents of botulism, block the neurotransmitter release by specifically cleaving one of the three SNARE proteins and induce flaccid paralysis. The Centers for Disease Control and Prevention (CDC) has declared them as Category A biowarfare agents. The most potent among them, botulinum neurotoxin type A (BoNT/A), cleaves its substrate synaptosome-associated protein of 25 kDa (SNAP-25). An efficient drug for botulism can be developed only with the knowledge of interactions between the substrate and enzyme at the active site. Here, we report the crystal structures of the catalytic domain of BoNT/A with its uncleavable SNAP-25 peptide (197)QRATKM(202) and its variant (197)RRATKM(202) to 1.5 A and 1.6 A, respectively. This is the first time the structure of an uncleavable substrate bound to an active botulinum neurotoxin is reported and it has helped in unequivocally defining S1 to S5' sites. These substrate peptides make interactions with the enzyme predominantly by the residues from 160, 200, 250 and 370 loops. Most notably, the amino nitrogen and carbonyl oxygen of P1 residue (Gln197) chelate the zinc ion and replace the nucleophilic water. The P1'-Arg198, occupies the S1' site formed by Arg363, Thr220, Asp370, Thr215, Ile161, Phe163 and Phe194. The S2' subsite is formed by Arg363, Asn368 and Asp370, while S3' subsite is formed by Tyr251, Leu256, Val258, Tyr366, Phe369 and Asn388. P4'-Lys201 makes hydrogen bond with Gln162. P5'-Met202 binds in the hydrophobic pocket formed by the residues from the 250 and 200 loop. Knowledge of interactions between the enzyme and substrate peptide from these complex structures should form the basis for design of potent inhibitors for this neurotoxin.
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71
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Agarwal R, Swaminathan S. SNAP-25 substrate peptide (residues 180-183) binds to but bypasses cleavage by catalytically active Clostridium botulinum neurotoxin E. J Biol Chem 2008; 283:25944-51. [PMID: 18658150 DOI: 10.1074/jbc.m803756200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Clostridium botulinum neurotoxins are the most potent toxins to humans. The recognition and cleavage of SNAREs are prime evente in exhibiting their toxicity. We report here the crystal structure of the catalytically active full-length botulinum serotype E catalytic domain (BoNT E) in complex with SNAP-25 (a SNARE protein) substrate peptide Arg(180)-Ile(181)-Met(182)-Glu(183) (P1-P3'). It is remarkable that the peptide spanning the scissile bond binds to but bypasses cleavage by the enzyme and inhibits the catalysis fairly with K(i) approximately 69 microm. The inhibitory peptide occupies the active site of BoNT E and shows well defined electron density. The catalytic zinc and the conserved key residue Tyr(350) of the enzyme facilitate the docking of Arg(180) (P1) by interacting with its carbonyl oxygen that displaces the nucleophilic water. The general base Glu(212) side chain interacts with the main chain amino group of P1 and P1'. Conserved Arg(347) of BoNT E stabilizes the proper docking of the Ile(181) (P1') main chain, whereas the hydrophobic pockets stabilize the side chains of Ile(181) (P1') and Met(182) (P2'), and the 250 loop stabilizes Glu(183) (P3'). Structural and functional analysis revealed an important role for the P1' residue and S1' pocket in driving substrate recognition and docking at the active site. This study is the first of its kind and rationalizes the substrate cleavage strategy of BoNT E. Also, our complex structure opens up an excellent opportunity of structure-based drug design for this fast acting and extremely toxic high priority BoNT E.
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Affiliation(s)
- Rakhi Agarwal
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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72
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Liang Y. Applications of isothermal titration calorimetry in protein science. Acta Biochim Biophys Sin (Shanghai) 2008; 40:565-76. [PMID: 18604448 DOI: 10.1111/j.1745-7270.2008.00437.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
During the past decade, isothermal titration calorimetry (ITC) has developed from a specialist method for understanding molecular interactions and other biological processes within cells to a more robust, widely used method. Nowadays, ITC is used to investigate all types of protein interactions, including protein-protein interactions, protein-DNA/RNA interactions, protein-small molecule interactions and enzyme kinetics; it provides a direct route to the complete thermodynamic characterization of protein interactions. This review concentrates on the new applications of ITC in protein folding and misfolding, its traditional application in protein interactions, and an overview of what can be achieved in the field of protein science using this method and what developments are likely to occur in the near future. Also, this review discusses some new developments of ITC method in protein science, such as the reverse titration of ITC and the displacement method of ITC.
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Affiliation(s)
- Yi Liang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China.
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73
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Botulinum neurotoxin interactions with substrate. Toxicon 2008. [DOI: 10.1016/j.toxicon.2008.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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74
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Silvaggi NR, Wilson D, Tzipori S, Allen KN. Catalytic features of the botulinum neurotoxin A light chain revealed by high resolution structure of an inhibitory peptide complex. Biochemistry 2008; 47:5736-45. [PMID: 18457419 DOI: 10.1021/bi8001067] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The Clostridium botulinum neurotoxin serotype A light chain (BoNT/A-LC) is a Zn(II)-dependent metalloprotease that blocks the release of acetylcholine at the neuromuscular junction by cleaving SNAP-25, one of the SNARE proteins required for exocytosis. Because of the potential for use of the toxin in bioterrorism and the increasingly widespread application of the toxin in the medical field, there is significant interest in the development of small-molecule inhibitors of the metalloprotease. Efforts to design such inhibitors have not benefited from knowledge of how peptides bind to the active site since the enzyme-peptide structures available previously either were not occupied in the vicinity of the catalytic Zn(II) ion or did not represent the product of SNAP-25 substrate cleavage. Herein we report the 1.4 A-resolution X-ray crystal structure of a complex between the BoNT/A-LC and the inhibitory peptide N-Ac-CRATKML, the first structure of the light chain with an inhibitory peptide bound at the catalytic Zn(II) ion. The peptide is bound with the Cys S gamma atom coordinating the metal ion. Surprisingly, the cysteine sulfur is oxidized to the sulfenic acid form. Given the unstable nature of this species in solution, is it likely that oxidation occurs on the enzyme. In addition to the peptide-bound structure, we report two structures of the unliganded light chain with and without the Zn(II) cofactor bound at 1.25 and 1.20 A resolution, respectively. The two structures are nearly identical, confirming that the Zn(II) ion plays a purely catalytic role. Additionally, the structure of the Zn(II)-bound uncomplexed enzyme allows identification of the catalytic water molecule and a second water molecule that occupies the same position as the peptidic oxygen in the tetrahedral intermediate. This observation suggests that the enzyme active site is prearranged to stabilize the tetrahedral intermediate of the protease reaction.
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Affiliation(s)
- Nicholas R Silvaggi
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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75
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Kumaran D, Rawat R, Ludivico ML, Ahmed SA, Swaminathan S. Structure- and substrate-based inhibitor design for Clostridium botulinum neurotoxin serotype A. J Biol Chem 2008; 283:18883-91. [PMID: 18434312 DOI: 10.1074/jbc.m801240200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The seven antigenically distinct serotypes of Clostridium botulinum neurotoxins cleave specific soluble N-ethylmaleimide-sensitive factor attachment protein receptor complex proteins and block the release of neurotransmitters that cause flaccid paralysis and are considered potential bioweapons. Botulinum neurotoxin type A is the most potent among the clostridial neurotoxins, and to date there is no post-exposure therapeutic intervention available. To develop inhibitors leading to drug design, it is imperative that critical interactions between the enzyme and the substrate near the active site are known. Although enzyme-substrate interactions at exosites away from the active site are mapped in detail for botulinum neurotoxin type A, information about the active site interactions is lacking. Here, we present the crystal structures of botulinum neurotoxin type A catalytic domain in complex with four inhibitory substrate analog tetrapeptides, viz. RRGC, RRGL, RRGI, and RRGM at resolutions of 1.6-1.8 A. These structures show for the first time the interactions between the substrate and enzyme at the active site and delineate residues important for substrate stabilization and catalytic activity. We show that OH of Tyr(366) and NH(2) of Arg(363) are hydrogen-bonded to carbonyl oxygens of P1 and P1' of the substrate analog and position it for catalytic activity. Most importantly, the nucleophilic water is replaced by the amino group of the N-terminal residue of the tetrapeptide. Furthermore, the S1' site is formed by Phe(194), Thr(215), Thr(220), Asp(370), and Arg(363). The K(i) of the best inhibitory tetrapeptide is 157 nm.
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Affiliation(s)
- Desigan Kumaran
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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76
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Hines HB, Kim AD, Stafford RG, Badie SS, Brueggeman EE, Newman DJ, Schmidt JJ. Use of a recombinant fluorescent substrate with cleavage sites for all botulinum neurotoxins in high-throughput screening of natural product extracts for inhibitors of serotypes A, B, and E. Appl Environ Microbiol 2008; 74:653-9. [PMID: 18083881 PMCID: PMC2227718 DOI: 10.1128/aem.01690-07] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 11/26/2007] [Indexed: 11/20/2022] Open
Abstract
The seven serotypes of botulinum neurotoxin (BoNTs) are zinc metalloproteases that cleave and inactivate proteins critical for neurotransmission. The synaptosomal protein of 25 kDa (SNAP-25) is cleaved by BoNTs A, C, and E, while vesicle-associated membrane protein (VAMP) is the substrate for BoNTs B, D, F, and G. BoNTs not only are medically useful drugs but also are potential bioterrorist and biowarfare threat agents. Because BoNT protease activity is required for toxicity, inhibitors of that activity might be effective for antibotulinum therapy. To expedite inhibitor discovery, we constructed a hybrid gene encoding (from the N terminus to the C terminus, with respect to the expressed product) green fluorescent protein, then a SNAP-25 fragment encompassing residues Met-127 to Gly-206, and then VAMP residues Met-1 to Lys-94. Cysteine was added as the C terminus. The expressed product, which contained the protease cleavage sites for all seven botulinum serotypes, was purified and coupled covalently through the C-terminal sulfhydryl group to maleimide-activated 96-well plates. The substrate was readily cleaved by BoNTs A, B, D, E, and F. Using this assay and an automated 96-well pipettor, we screened 528 natural product extracts for inhibitors of BoNT A, B, and E protease activities. Serotype-specific inhibition was found in 30 extracts, while 5 others inhibited two serotypes.
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Affiliation(s)
- Harry B Hines
- Department of Cell Biology and Biochemistry, Integrated Toxicology Division, USAMRIID, Frederick, MD 21702-5011, USA
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77
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Johnson SL, Chen LH, Harbach R, Sabet M, Savinov A, Cotton NJH, Strongin A, Guiney D, Pellecchia M. Rhodanine Derivatives as Selective Protease Inhibitors Against Bacterial Toxins. Chem Biol Drug Des 2008; 71:131-9. [DOI: 10.1111/j.1747-0285.2007.00617.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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78
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Eubanks LM, Dickerson TJ. Investigating novel therapeutic targets and molecular mechanisms to treat botulinum neurotoxin A intoxication. Future Microbiol 2008; 2:677-87. [PMID: 18041908 DOI: 10.2217/17460913.2.6.677] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Botulinum neurotoxin (BoNT) has recently catapulted into the public consciousness in two seemingly disparate roles: potential use as a biological weapon and treatment of neuromuscular disorders. This bacterially produced protein is the most potent toxin known to humans, with a lethal dose estimated at approximately 1 ng/kg of body weight. BoNT intoxication occurs via a multistep process that includes recognition of peripheral neuronal cell membrane receptors, endocytosis and translocation of the light chain metalloprotease into the cytosol, and catalytic cleavage of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins critical for vesicle fusion and neurotransmitter release. Each of these distinct steps has been studied at the molecular level and is a valid target for the development of pharmacological interventions to prevent the considerable mortality associated with botulism. Alternatively, clinical uses of BoNT continue to expand at an ever-increasing rate; however, further optimization of BoNT therapy is critical to maximize efficacy.
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Affiliation(s)
- Lisa M Eubanks
- The Scripps Research Institute, Department of Chemistry, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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79
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Tang J, Park JG, Millard CB, Schmidt JJ, Pang YP. Computer-aided lead optimization: improved small-molecule inhibitor of the zinc endopeptidase of botulinum neurotoxin serotype A. PLoS One 2007; 2:e761. [PMID: 17712409 PMCID: PMC1942119 DOI: 10.1371/journal.pone.0000761] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Accepted: 07/16/2007] [Indexed: 11/23/2022] Open
Abstract
Optimization of a serotype-selective, small-molecule inhibitor of botulinum neurotoxin serotype A (BoNTA) endopeptidase is a formidable challenge because the enzyme-substrate interface is unusually large and the endopeptidase itself is a large, zinc-binding protein with a complex fold that is difficult to simulate computationally. We conducted multiple molecular dynamics simulations of the endopeptidase in complex with a previously described inhibitor (Kiapp of 7±2.4 µM) using the cationic dummy atom approach. Based on our computational results, we hypothesized that introducing a hydroxyl group to the inhibitor could improve its potency. Synthesis and testing of the hydroxyl-containing analog as a BoNTA endopeptidase inhibitor showed a twofold improvement in inhibitory potency (Kiapp of 3.8±0.8 µM) with a relatively small increase in molecular weight (16 Da). The results offer an improved template for further optimization of BoNTA endopeptidase inhibitors and demonstrate the effectiveness of the cationic dummy atom approach in the design and optimization of zinc protease inhibitors.
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Affiliation(s)
- Jing Tang
- Computer-Aided Molecular Design Laboratory, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Jewn Giew Park
- Computer-Aided Molecular Design Laboratory, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Charles B. Millard
- Division of Biochemistry, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - James J. Schmidt
- Department of Cell Biology and Biochemistry, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
- * To whom correspondence should be addressed. E-mail: (JS); (Y-PP)
| | - Yuan-Ping Pang
- Computer-Aided Molecular Design Laboratory, Mayo Clinic, Rochester, Minnesota, United States of America
- * To whom correspondence should be addressed. E-mail: (JS); (Y-PP)
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80
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Eubanks LM, Hixon MS, Jin W, Hong S, Clancy CM, Tepp WH, Baldwin MR, Malizio CJ, Goodnough MC, Barbieri JT, Johnson EA, Boger DL, Dickerson TJ, Janda KD. An in vitro and in vivo disconnect uncovered through high-throughput identification of botulinum neurotoxin A antagonists. Proc Natl Acad Sci U S A 2007; 104:2602-7. [PMID: 17293454 PMCID: PMC1815229 DOI: 10.1073/pnas.0611213104] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Among the agents classified as "Category A" by the U.S. Centers for Disease Control and Prevention, botulinum neurotoxin (BoNT) is the most toxic protein known, with microgram quantities of the protein causing severe morbidity and mortality by oral or i.v. routes. Given that this toxin easily could be used in a potential bioterrorist attack, countermeasures urgently are needed to counteract the pathophysiology of BoNT. At a molecular level, BoNT exerts its paralytic effects through intracellular cleavage of vesicle docking proteins and subsequent organism-wide autonomic dysfunction. In an effort to identify small molecules that would disrupt the interaction between the light-chain metalloprotease of BoNT serotype A and its cognate substrate, a multifaceted screening effort was undertaken. Through the combination of in vitro screening against an optimized variant of the light chain involving kinetic analysis, cellular protection assays, and in vivo mouse toxicity assays, molecules that prevent BoNT/A-induced intracellular substrate cleavage and extend the time to death of animals challenged with lethal toxin doses were identified. Significantly, the two most efficacious compounds in vivo showed less effective activity in cellular assays intended to mimic BoNT exposure; indeed, one of these compounds was cytotoxic at concentrations three orders of magnitude below its effective dose in animals. These two lead compounds have surprisingly simple molecular structures and are readily amenable to optimization efforts for improvements in their biological activity. The findings validate the use of high-throughput screening protocols to define previously unrecognized chemical scaffolds for the development of therapeutic agents to treat BoNT exposure.
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Affiliation(s)
- Lisa M. Eubanks
- Departments of *Chemistry and
- The Skaggs Institute for Chemical Biology, and
- The Worm Institute of Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
| | - Mark S. Hixon
- Departments of *Chemistry and
- The Skaggs Institute for Chemical Biology, and
- The Worm Institute of Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
| | - Wei Jin
- Departments of *Chemistry and
- The Skaggs Institute for Chemical Biology, and
| | - Sukwon Hong
- Departments of *Chemistry and
- The Skaggs Institute for Chemical Biology, and
| | - Colin M. Clancy
- Food Research Institute, University of Wisconsin, 1925 Willow Drive, Madison, WI 53706
| | - William H. Tepp
- Food Research Institute, University of Wisconsin, 1925 Willow Drive, Madison, WI 53706
| | - Michael R. Baldwin
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226; and
| | | | | | - Joseph T. Barbieri
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226; and
| | - Eric A. Johnson
- Food Research Institute, University of Wisconsin, 1925 Willow Drive, Madison, WI 53706
| | - Dale L. Boger
- Departments of *Chemistry and
- The Skaggs Institute for Chemical Biology, and
| | - Tobin J. Dickerson
- Departments of *Chemistry and
- The Skaggs Institute for Chemical Biology, and
- The Worm Institute of Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
- **To whom correspondence may be addressed. E-mail: or
| | - Kim D. Janda
- Departments of *Chemistry and
- Immunology
- The Skaggs Institute for Chemical Biology, and
- The Worm Institute of Research and Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
- **To whom correspondence may be addressed. E-mail: or
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