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Annual Review of Biochemistry Jun 2019Botulinum neurotoxins (BoNTs) and tetanus neurotoxin (TeNT) are the most potent toxins known and cause botulism and tetanus, respectively. BoNTs are also widely utilized... (Review)
Review
Botulinum neurotoxins (BoNTs) and tetanus neurotoxin (TeNT) are the most potent toxins known and cause botulism and tetanus, respectively. BoNTs are also widely utilized as therapeutic toxins. They contain three functional domains responsible for receptor-binding, membrane translocation, and proteolytic cleavage of host proteins required for synaptic vesicle exocytosis. These toxins also have distinct features: BoNTs exist within a progenitor toxin complex (PTC), which protects the toxin and facilitates its absorption in the gastrointestinal tract, whereas TeNT is uniquely transported retrogradely within motor neurons. Our increasing knowledge of these toxins has allowed the development of engineered toxins for medical uses. The discovery of new BoNTs and BoNT-like proteins provides additional tools to understand the evolution of the toxins and to engineer toxin-based therapeutics. This review summarizes the progress on our understanding of BoNTs and TeNT, focusing on the PTC, receptor recognition, new BoNT-like toxins, and therapeutic toxin engineering.
Topics: Animals; Botulinum Toxins; Humans; Metalloendopeptidases; Protein Conformation; Protein Engineering; Tetanus Toxin
PubMed: 30388027
DOI: 10.1146/annurev-biochem-013118-111654 -
Journal of Neurochemistry Sep 2021Tetanus is a deadly but preventable disease caused by a protein neurotoxin produced by Clostridium tetani. Spores of C. tetani may contaminate a necrotic wound and... (Review)
Review
Tetanus is a deadly but preventable disease caused by a protein neurotoxin produced by Clostridium tetani. Spores of C. tetani may contaminate a necrotic wound and germinate into a vegetative bacterium that releases a toxin, termed tetanus neurotoxin (TeNT). TeNT enters the general circulation, binds to peripheral motor neurons and sensory neurons, and is transported retroaxonally to the spinal cord. It then enters inhibitory interneurons and blocks the release of glycine or GABA causing a spastic paralysis. This review attempts to correlate the metalloprotease activity of TeNT and its trafficking and localization into the vertebrate body to the nature and sequence of appearance of the symptoms of tetanus.
Topics: Animals; Brain; Humans; Neurotoxins; Peripheral Nerves; Spinal Cord; Tetanus; Tetanus Toxin; Tetanus Toxoid
PubMed: 33629408
DOI: 10.1111/jnc.15330 -
Vaccine Aug 2022Tetanus toxoid (TTxd), developed over 100 years ago, is a clinically effective, legacy vaccine against tetanus. Due to the extreme potency of native tetanus toxin,...
Tetanus toxoid (TTxd), developed over 100 years ago, is a clinically effective, legacy vaccine against tetanus. Due to the extreme potency of native tetanus toxin, manufacturing and regulatory efforts often focus on TTxd production, standardization, and safety, rather than product modernization. Recently, a genetically detoxified, full-length tetanus toxin protein (8MTT) was reported as a tetanus vaccine alternative to TTxd (Przedpelski et al. mBio, 2020). Here we describe the production of 8MTT in Gor/Met E. coli, a strain engineered to have an oxidative cytoplasm, allowing for the expression of soluble, disulfide-bonded proteins. The strain was also designed to efficiently cleave N-terminal methionine, the obligatory start amino acid for E. coli expressed proteins. 8MTT was purified as a soluble protein from the cytoplasm in a two-column protocol to > 99 % purity, yielding 0.5 g of purified 8MTT/liter of fermentation broth with low endotoxin contamination, and antigenic purity of 3500 Lf/mg protein nitrogen. Mouse immunizations showed 8MTT to be an immunogenic vaccine and effective as a carrier protein for peptide and polysaccharide conjugates. These studies validate 8MTT as commercially viable and, unlike the heterogenous tetanus toxoid, a uniform carrier protein for conjugate vaccines. The development of a recombinant, genetically detoxified toxin produced in E. coli aligns the tetanus vaccine with modern manufacturing, regulatory, standardization, and safety requirements.
Topics: Animals; Antibodies, Bacterial; Carrier Proteins; Escherichia coli; Mice; Tetanus; Tetanus Toxin; Tetanus Toxoid; Vaccines, Conjugate
PubMed: 35871872
DOI: 10.1016/j.vaccine.2022.07.011 -
Microbiological Reviews Jun 1979
Review
Topics: Animals; Cell Membrane; Cells, Cultured; Central Nervous System; Chemical Phenomena; Chemistry; Clostridium tetani; Gangliosides; Humans; Models, Chemical; Receptors, Drug; Tetanus; Tetanus Toxin
PubMed: 390355
DOI: 10.1128/mr.43.2.224-240.1979 -
Toxins Nov 2022We review some of the precursor works of the Pasteurians in the field of bacterial toxins. The word "toxin" was coined in 1888 by Ludwig Brieger to qualify different... (Review)
Review
We review some of the precursor works of the Pasteurians in the field of bacterial toxins. The word "toxin" was coined in 1888 by Ludwig Brieger to qualify different types of poison released by bacteria. Pasteur had identified the bacteria as the cause of putrefaction but never used the word toxin. In 1888, Émile Roux and Alexandre Yersin were the first to demonstrate that the bacteria causing diphtheria was releasing a deadly toxin. In 1923, Gaston Ramon treated that toxin with formalin and heat, resulting in the concept of "anatoxin" as a mean of vaccination. A similar approach was performed to obtain the tetanus anatoxin by Pierre Descombey, Christian Zoeller and G. Ramon. On his side, Elie Metchnikoff also studied the tetanus toxin and investigated the cholera toxin. His colleague from Odessa, Nikolaï GamaleÏa who was expected to join Institut Pasteur, wrote the first book on bacterial poisons while other Pasteurians such as Etienne Burnet, Maurice Nicolle, Emile Césari, and Constant Jouan wrote books on toxins. Concerning the endotoxins, Alexandre Besredka obtained the first immune antiserum against lipopolysaccharide, and André Boivin characterized the biochemical nature of the endotoxins in a work initiated with Lydia Mesrobeanu in Bucharest.
Topics: Humans; Tetanus; Endotoxins; Tetanus Toxin; Bacteria; Poisons
PubMed: 36356009
DOI: 10.3390/toxins14110759 -
Toxins Nov 2019Tetanus and botulinum neurotoxins are the most poisonous substances known, so much so as to be considered for a possible terrorist use. At the same time, botulinum... (Review)
Review
Tetanus and botulinum neurotoxins are the most poisonous substances known, so much so as to be considered for a possible terrorist use. At the same time, botulinum neurotoxin type A1 is successfully used to treat a variety of human syndromes characterized by hyperactive cholinergic nerve terminals. The extreme toxicity of these neurotoxins is due to their neurospecificity and to their metalloprotease activity, which results in the deadly paralysis of tetanus and botulism. Recently, many novel botulinum neurotoxins and some botulinum-like toxins have been discovered. This large number of toxins differs in terms of toxicity and biological activity, providing a potential goldmine for novel therapeutics and for new molecular tools to dissect vesicular trafficking, fusion, and exocytosis. The scattered data on toxicity present in the literature require a systematic organization to be usable by scientists and clinicians. We have assembled here the data available in the literature on the toxicity of these toxins in different animal species. The internal comparison of these data provides insights on the biological activity of these toxins.
Topics: Animals; Botulinum Toxins; Humans; Lethal Dose 50; Neurotoxins; Tetanus Toxin
PubMed: 31771110
DOI: 10.3390/toxins11120686 -
Toxicon : Official Journal of the... Jun 2018Tetanus (TeNT) and botulinum (BoNT) neurotoxins, the causative agents of tetanus and botulism, respectively, are the most potent toxic molecules known to mankind. This... (Review)
Review
Tetanus (TeNT) and botulinum (BoNT) neurotoxins, the causative agents of tetanus and botulism, respectively, are the most potent toxic molecules known to mankind. This extreme potency is attributed to: i) their specificity for essential components of the neurotransmitter release machinery present at vertebrate synapses, and ii) their high-affinity targeting to motor neurons by binding to polysialogangliosides and protein receptors. Comprising the clostridial neurotoxin family, TeNT and BoNTs engage distinct surface receptors and intracellular sorting pathways in neurons. BoNTs bind to the intraluminal domain of specific synaptic vesicle proteins that are exposed to the extracellular milieu upon exocytosis, and are taken up by synaptic vesicle recycling. A sizeable proportion of BoNT molecules remain at the neuromuscular junction, where their protease moiety is released into the cytoplasm, blocking synaptic transmission and causing flaccid paralysis. In contrast, TeNT undergoes binding to specific components of the basal membrane at the neuromuscular junction, is endocytosed into motor neurons and sorted to axonal signalling endosomes. Following this, TeNT is transported to the soma of motor neurons located in the spinal cord or brainstem, and then transcytosed to inhibitory interneurons, where it blocks synaptic transmission. TeNT-induced impairment of inhibitory input leads to hyperactivity of motor neurons, causing spastic paralysis, which is the hallmark of tetanus. This review examines the molecular mechanisms leading to the entry, sorting and intracellular trafficking of TeNT and BoNTs.
Topics: Animals; Botulinum Toxins; Humans; Protein Transport; Tetanus Toxin
PubMed: 29031941
DOI: 10.1016/j.toxicon.2017.10.008 -
MSphere May 2020The clostridial neurotoxins (CNTs) comprise tetanus toxin (TT) and botulinum neurotoxin (BoNT [BT]) serotypes (A to G and X) and several recently identified CNT-like...
The clostridial neurotoxins (CNTs) comprise tetanus toxin (TT) and botulinum neurotoxin (BoNT [BT]) serotypes (A to G and X) and several recently identified CNT-like proteins, including BT/En and the mosquito BoNT-like toxin Pmp1. CNTs are produced as single proteins cleaved to a light chain (LC) and a heavy chain (HC) connected by an interchain disulfide bond. LC is a zinc metalloprotease (cleaving oluble -ethylmaleimide-sensitive factor ttachment protein ceptors [SNAREs]), while HC contains an N-terminal translocation domain (HCN) and a C-terminal receptor binding domain (HCC). HCN-mediated LC translocation is the least understood function of CNT action. Here, β-lactamase (βlac) was used as a reporter in discovery-based live-cell assays to characterize TT-mediated LC translocation. Directed mutagenesis identified a role for a charged loop (DKE) connecting α15 and α16 (-loop) within HCN in LC translocation; aliphatic substitution inhibited LC translocation but not other toxin functions such as cell binding, intracellular trafficking, or HCN-mediated pore formation. K was conserved among the CNTs. In molecular simulations of the HCN with a membrane, the -loop did not bind with the cell membrane. Taken together, the results of these studies implicate the -loop in LC translocation, independently of pore formation. How protein toxins translocate their catalytic domain across a cell membrane is the least understood step in toxin action. This study utilized a reporter, β-lactamase, that was genetically fused to full-length, nontoxic tetanus toxin (βlac-TT) in discovery-based live-cell assays to study LC translocation. Directed mutagenesis identified a role for K in LC translocation. K was located between α15 and α16 (termed the -loop). Cellular assays showed that K did not interfere with other toxin functions, including cell binding, intracellular trafficking, and pore formation. The equivalent K is conserved among the clostridial neurotoxin family of proteins as a conserved structural motif. The -loop appears to contribute to LC translocation.
Topics: Animals; Botulinum Toxins; Cell Line; Cell Membrane; Cells, Cultured; Mice; Neurons; Protein Binding; Protein Transport; Rats; Tetanus Toxin; Translocation, Genetic
PubMed: 32376703
DOI: 10.1128/mSphere.00244-20 -
Nature Neuroscience Jun 2020Descending command neurons instruct spinal networks to execute basic locomotor functions, such as gait and speed. The command functions for gait and speed are symmetric,...
Descending command neurons instruct spinal networks to execute basic locomotor functions, such as gait and speed. The command functions for gait and speed are symmetric, implying that a separate unknown system directs asymmetric movements, including the ability to move left or right. In the present study, we report that Chx10-lineage reticulospinal neurons act to control the direction of locomotor movements in mammals. Chx10 neurons exhibit mainly ipsilateral projection, and their selective unilateral activation causes ipsilateral turning movements in freely moving mice. Unilateral inhibition of Chx10 neurons causes contralateral turning movements. Paired left-right motor recordings identified distinct mechanisms for directional movements mediated via limb and axial spinal circuits. Finally, we identify sensorimotor brain regions that project on to Chx10 reticulospinal neurons, and demonstrate that their unilateral activation can impart left-right directional commands. Together these data identify the descending motor system that commands left-right locomotor asymmetries in mammals.
Topics: Animals; Brain Stem; Clozapine; Efferent Pathways; Homeodomain Proteins; Locomotion; Mice; Neuroanatomical Tract-Tracing Techniques; Neurons; Tetanus Toxin; Transcription Factors
PubMed: 32393896
DOI: 10.1038/s41593-020-0633-7 -
Toxins Nov 2010In many neurological disorders strategies for a specific delivery of a biological activity from the periphery to the central nervous system (CNS) remains a considerable... (Review)
Review
In many neurological disorders strategies for a specific delivery of a biological activity from the periphery to the central nervous system (CNS) remains a considerable challenge for successful therapy. Reporter assays have established that the non-toxic C-fragment of tetanus toxin (TTC), provided either as protein or encoded by non-viral naked DNA plasmid, binds pre-synaptic motor neuron terminals and can facilitate the retrograde axonal transport of desired therapeutic molecules to the CNS. Alleviated symptoms in animal models of neurological diseases upon delivery of therapeutic molecules offer a hopeful prospect for TTC therapy. This review focuses on what has been learned on TTC-mediated neuronal targeting, and discusses the recent discovery that, instead of being merely a carrier molecule, TTC itself may well harbor neuroprotective properties.
Topics: Animals; Axonal Transport; Disease Models, Animal; Gene Targeting; Genetic Therapy; Humans; Molecular Targeted Therapy; Motor Neuron Disease; Motor Neurons; Neural Pathways; Neurodegenerative Diseases; Neuromuscular Junction; Neuroprotective Agents; Peptide Fragments; Presynaptic Terminals; Tetanus Toxin
PubMed: 22069568
DOI: 10.3390/toxins2112622