Entry of Botulinum Neurotoxin Subtypes A1 and A2 into Neurons

Kroken, Abby R.; Blum, Faith C.; Zuverink, Madison; Barbieri, Joseph T.

doi:10.1128/iai.00795-16

Cited by 29 publications

(32 citation statements)

References 56 publications

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“…This difference in combination of water‐mediated interactions and hydrogen bond interactions would be consistent with the relative ganglioside binding affinities of BoNT/A1 and suggests that BoNT/A3 binds GD1a with a lower affinity than BoNT/A1. Furthermore, the difference in degree of interaction between ganglioside and H C may partly explain the reported difference in potency between BoNT/A1 and BoNT/A3 and would be consistent with the observation that BoNT/A2 has a higher affinity for gangliosides than BoNT/A1 and also enters neuronal cells more efficiently .…”

Section: Resultssupporting

confidence: 85%

Crystal structure of botulinum neurotoxin subtype A3 cell binding domain in complex with GD1a co‐receptor ganglioside

2020

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Botulinum neurotoxins (BoNTs) are one of the most toxic proteins known to humans. Their molecular structure is comprised of three essential domains—a cell binding domain (HC), translocation domain and catalytic domain (light chain) . The HC domain facilitates the highly specific binding of BoNTs to the neuronal membrane via a dual‐receptor complex involving a protein receptor and a ganglioside. Variation in activity/toxicity across subtypes of serotype A has been attributed to changes in protein and ganglioside interactions, and their implications are important in the design of novel BoNT‐based therapeutics. Here, we present the structure of BoNT/A3 cell binding domain (HC/A3) in complex with the ganglioside GD1a at 1.75 Å resolution. The structure revealed that six residues interact with the three outermost monosaccharides of GD1a through several key hydrogen bonding interactions. A detailed comparison of structures of HC/A3 with HC/A1 revealed subtle conformational differences at the ganglioside binding site upon carbohydrate binding.

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Section: Resultssupporting

confidence: 85%

Crystal structure of botulinum neurotoxin subtype A3 cell binding domain in complex with GD1a co‐receptor ganglioside

2020

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“…In addition, ganglioside binding specificity and affinity varies amongst the serotypes. BoNT/B and/C bind gangliosides with greater affinity than BoNT/A1 [52], while BoNT/A2 appears to interact with polysialogangliosides with greater affinity than BoNT/A1 [53,54]. Cell entry kinetics also differ within the BoNT types, with BoNT/E,/A2, and/A6 entering neuronal cells faster than BoNT/A1 [55][56][57].…”

Section: Introductionmentioning

confidence: 98%

Critical Analysis of Neuronal Cell and the Mouse Bioassay for Detection of Botulinum Neurotoxins

Pellett

Tepp

Johnson

2019

Toxins

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Botulinum Neurotoxins (BoNTs) are a large protein family that includes the most potent neurotoxins known to humankind. BoNTs delivered locally in humans at low doses are widely used pharmaceuticals. Reliable and quantitative detection of BoNTs is of paramount importance for the clinical diagnosis of botulism, basic research, drug development, potency determination, and detection in clinical, environmental, and food samples. Ideally, a definitive assay for BoNT should reflect the activity of each of the four steps in nerve intoxication. The in vivo mouse bioassay (MBA) is the 'gold standard' for the detection of BoNTs. The MBA is sensitive, robust, semi-quantitative, and reliable within its sensitivity limits. Potential drawbacks with the MBA include assay-to-assay potency variations, especially between laboratories, and false positives or negatives. These limitations can be largely avoided by careful planning and performance. Another detection method that has gained importance in recent years for research and potency determination of pharmaceutical BoNTs is cell-based assays, as these assays can be highly sensitive, quantitative, human-specific, and detect fully functional holotoxins at physiologically relevant concentrations. A myriad of other in vitro BoNT detection methods exist. This review focuses on critical factors and assay limitations of the mouse bioassay and cell-based assays for BoNT detection. Key Contribution:This manuscript reviews two widely used botulinum neurotoxin detection assays, the mouse bioassay and cell-based assays, and the critical factors involved in their methodology as well as interpretation of results. Despite our ability to now reduce animal use and replace the mouse bioassay for certain aspects of botulinum neurotoxin detection, the mouse bioassay is sensitive and is the only in vivo assay considering all aspects of botulinum neurotoxin intoxication on a physiological level as well as pharmacokinetic aspects of the toxins, and thus remains important assay for botulinum neurotoxin detection.Toxins 2019, 11, 713 2 of 23 cells, with preferential entry into motor-neurons. Inside a neuron, the toxins block neurotransmitter release, leading to the long-lasting descending bilateral paralysis characteristic of botulism [6]. Even if applied intramuscularly for therapeutic purposes, a portion of the injected BoNTs, in particular at high doses, can diffuse away from the local injection site leading to distal neuronal effects and at very high doses systemic distribution [7][8][9][10]. BoNTs can also enter human or vertebrate circulation and cause botulism by different routes, including ingestion of contaminated foods, by wound infection with neurotoxigenic clostridia, and by the colonization of the intestinal tract by neurotoxigenic clostridia, causing infant botulism or adult intestinal botulism [11,12]. The latter is rare, as C. botulinum usually does not colonize a healthy intestine with a mature microbiota. The severe symptoms of botulism last from several days to up to a year, depending ...

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“…Amino acid sequence variations might impact BoNT biological functions including receptor recognition, the efficiency of entry into cells and persistence, recognition by monoclonal antibodies, and enzymatic activity. For example, BoNT/A2 has been shown to enter more efficiently into neuronal cells than BoNT/A1 and to have a higher affinity for its receptor [77,78].…”

Section: Botulinum Toxin Diversitymentioning

confidence: 99%

Botulinum Toxins, Diversity, Mode of Action, Epidemiology of Botulism in France

Popoff¹

2018

Botulinum Toxin

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Botulinum toxins (BoNTs) are the most potent toxins and are responsible for botulism, which is a neurological disease in man and animals. Botulism is characterized by flaccid paralysis and inhibition of secretions. BoNTs are produced by distinct clostridial species including Clostridium botulinum that consist in four physiological and genetic groups, atypical strains of C. baratii and C. butyricum. Recently, nonclostridial bacteria have been found to synthesize BoNTs. The particularity of BoNTs is to associate with nontoxic proteins to form large-size complexes that are resistant to acidic pH and protease degradation of the digestive tract. BoNTs are divided into 10 types based on neutralization by specific antisera and into more than 40 subtypes according to their sequence variations. All BoNTs retain a common core structure and mode of action, which consists in the inhibition of neurotransmitter release, notably acetylcholine. Human botulism occurs in three main forms: foodborne botulism, botulism by intestinal colonization including infant botulism, and wound botulism. In France, type B foodborne botulism is the most prevalent form, resulting from the traditional consumption of pork products such as home-made cured ham. Albeit less frequent, human botulism is still present in France including diverse types and origins.

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Entry of Botulinum Neurotoxin Subtypes A1 and A2 into Neurons

Cited by 29 publications

References 56 publications

Crystal structure of botulinum neurotoxin subtype A3 cell binding domain in complex with GD1a co‐receptor ganglioside

Crystal structure of botulinum neurotoxin subtype A3 cell binding domain in complex with GD1a co‐receptor ganglioside

Critical Analysis of Neuronal Cell and the Mouse Bioassay for Detection of Botulinum Neurotoxins

Botulinum Toxins, Diversity, Mode of Action, Epidemiology of Botulism in France

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