Dataset Information

Covalent Modifiers of Botulinum Neurotoxin Counteract Toxin Persistence.

ABSTRACT: Botulinum neurotoxins (BoNTs) are the most potent toxins known to man and a significant threat as weapons of bioterrorism. BoNTs contain a metalloprotease domain that blocks neurotransmitter release in nerve terminals, resulting in a descending, flaccid paralysis with a 5-10% mortality rate. Existing treatment options cannot access or neutralize the toxin following its endocytosis, so there is a clear need to develop novel therapies. Numerous substrate-based and zinc-chelating small-molecule inhibitors have been reported; however, none have progressed to the clinic. This is likely due to the difficulty that reversible inhibitors have in achieving sustained inhibition of the toxin, which has a half-life of months in vivo. An alternative strategy for mitigating BoNT persistence is covalent, irreversible inhibition of toxin function. However, few examples of covalent BoNT inhibitors have been reported. Here, we describe a competition-based screen to identify covalent modifiers of the conserved active-site-adjacent cysteine C165 in the BoNT/A serotype. We found that compounds containing cysteine-reactive electrophiles designed to target cysteine proteases failed to bind C165 while selenide compounds were efficient covalent binders of this cysteine. Importantly, covalent modification at C165 resulted in sustained, irreversible inhibition of BoNT/A protease activity. Covalent selenide inhibitors were nontoxic and protective in a neuronal assay of intoxication, making them promising new scaffolds for the study of the BoNT/A toxin as well as for the design of novel therapy agents.

SUBMITTER: Garland M

PROVIDER: S-EPMC7204532 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Covalent Modifiers of Botulinum Neurotoxin Counteract Toxin Persistence.

Garland Megan M Babin Brett M BM Miyashita Shin-Ichiro SI Loscher Sebastian S Shen Yi Y Dong Min M Bogyo Matthew M

ACS chemical biology 20190108 1

Botulinum neurotoxins (BoNTs) are the most potent toxins known to man and a significant threat as weapons of bioterrorism. BoNTs contain a metalloprotease domain that blocks neurotransmitter release in nerve terminals, resulting in a descending, flaccid paralysis with a 5-10% mortality rate. Existing treatment options cannot access or neutralize the toxin following its endocytosis, so there is a clear need to develop novel therapies. Numerous substrate-based and zinc-chelating small-molecule inh ...[more]

PMID: 30571080

Similar Datasets

Project description: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 ?- and ?-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.

Dataset Information

Covalent Modifiers of Botulinum Neurotoxin Counteract Toxin Persistence.

Publications

Covalent Modifiers of Botulinum Neurotoxin Counteract Toxin Persistence.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets