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Wentz TG, Tremblay BJM, Bradshaw M, Doxey AC, Sharma SK, Sauer JD, Pellett S. Endogenous CRISPR-Cas Systems in Group I Clostridium botulinum and Clostridium sporogenes Do Not Directly Target the Botulinum Neurotoxin Gene Cluster. Front Microbiol 2022; 12:787726. [PMID: 35222299 PMCID: PMC8865420 DOI: 10.3389/fmicb.2021.787726] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/27/2021] [Indexed: 12/28/2022] Open
Abstract
Most strains of proteolytic group I Clostridium botulinum (G1 C. botulinum) and some strains of Clostridium sporogenes possess genes encoding botulinum neurotoxin (BoNT), a potent neuroparalytic agent. Within G1 C. botulinum, conserved bont gene clusters of three major toxin serotypes (bont/A/B/F) can be found on conjugative plasmids and/or within chromosomal pathogenicity islands. CRISPR-Cas systems enable site-specific targeting of previously encountered mobile genetic elements (MGE) such as plasmids and bacteriophage through the creation of a spacer library complementary to protospacers within the MGEs. To examine whether endogenous CRISPR-Cas systems restrict the transfer of bont gene clusters across strains we conducted a bioinformatic analysis profiling endogenous CRISPR-Cas systems from 241 G1 C. botulinum and C. sporogenes strains. Approximately 6,200 CRISPR spacers were identified across the strains and Type I-B, III-A/B/D cas genes and CRISPR array features were identified in 83% of the strains. Mapping the predicted spacers against the masked strain and RefSeq plasmid dataset identified 56,000 spacer-protospacer matches. While spacers mapped heavily to targets within bont(+) plasmids, no protospacers were identified within the bont gene clusters. These results indicate the toxin is not a direct target of CRISPR-Cas but the plasmids predominantly responsible for its mobilization are. Finally, while the presence of a CRISPR-Cas system did not reliably indicate the presence or absence of a bont gene cluster, comparative genomics across strains indicates they often occupy the same hypervariable loci common to both species, potentially suggesting similar mechanisms are involved in the acquisition and curation of both genomic features.
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Affiliation(s)
- Travis G. Wentz
- Microbiology Doctoral Training Program, University of Wisconsin–Madison, Madison, WI, United States,Division of Microbiology, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD, United States,Department of Bacteriology, University of Wisconsin–Madison, Madison, WI, United States
| | | | - Marite Bradshaw
- Department of Bacteriology, University of Wisconsin–Madison, Madison, WI, United States
| | - Andrew C. Doxey
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Shashi K. Sharma
- Division of Microbiology, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD, United States
| | - John-Demian Sauer
- Department of Medical Microbiology and Immunology, University of Wisconsin–Madison, Madison, WI, United States
| | - Sabine Pellett
- Department of Bacteriology, University of Wisconsin–Madison, Madison, WI, United States,*Correspondence: Sabine Pellett,
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Cai S, Kumar R, Singh BR. Clostridial Neurotoxins: Structure, Function and Implications to Other Bacterial Toxins. Microorganisms 2021; 9:2206. [PMID: 34835332 PMCID: PMC8618262 DOI: 10.3390/microorganisms9112206] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/19/2021] [Accepted: 10/19/2021] [Indexed: 01/20/2023] Open
Abstract
Gram-positive bacteria are ancient organisms. Many bacteria, including Gram-positive bacteria, produce toxins to manipulate the host, leading to various diseases. While the targets of Gram-positive bacterial toxins are diverse, many of those toxins use a similar mechanism to invade host cells and exert their functions. Clostridial neurotoxins produced by Clostridial tetani and Clostridial botulinum provide a classical example to illustrate the structure-function relationship of bacterial toxins. Here, we critically review the recent progress of the structure-function relationship of clostridial neurotoxins, including the diversity of the clostridial neurotoxins, the mode of actions, and the flexible structures required for the activation of toxins. The mechanism clostridial neurotoxins use for triggering their activity is shared with many other Gram-positive bacterial toxins, especially molten globule-type structures. This review also summarizes the implications of the molten globule-type flexible structures to other Gram-positive bacterial toxins. Understanding these highly dynamic flexible structures in solution and their role in the function of bacterial toxins not only fills in the missing link of the high-resolution structures from X-ray crystallography but also provides vital information for better designing antidotes against those toxins.
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Affiliation(s)
- Shuowei Cai
- Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, Dartmouth, MA 02747, USA
| | - Raj Kumar
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA; (R.K.); (B.R.S.)
| | - Bal Ram Singh
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA; (R.K.); (B.R.S.)
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Davies JR, Masuyer G, Stenmark P. Structural and Biochemical Characterization of Botulinum Neurotoxin Subtype B2 Binding to Its Receptors. Toxins (Basel) 2020; 12:toxins12090603. [PMID: 32957706 PMCID: PMC7551386 DOI: 10.3390/toxins12090603] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/14/2020] [Accepted: 09/16/2020] [Indexed: 12/31/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) can be used therapeutically to treat a wide range of neuromuscular and neurological conditions. A collection of natural BoNT variants exists which can be classified into serologically distinct serotypes (BoNT/B), and further divided into subtypes (BoNT/B1, B2, …). BoNT subtypes share a high degree of sequence identity within the same serotype yet can display large variation in toxicity. One such example is BoNT/B2, which was isolated from Clostridium botulinum strain 111 in a clinical case of botulism, and presents a 10-fold lower toxicity than BoNT/B1. In an effort to understand the molecular mechanisms behind this difference in potency, we here present the crystal structures of BoNT/B2 in complex with the ganglioside receptor GD1a, and with the human synaptotagmin I protein receptor. We show, using receptor-binding assays, that BoNT/B2 has a slightly higher affinity for GD1a than BoNT/B1, and confirm its considerably weaker affinity for its protein receptors. Although the overall receptor-binding mechanism is conserved for both receptors, structural analysis suggests the lower affinity of BoNT/B2 is the result of key substitutions, where hydrophobic interactions important for synaptotagmin-binding are replaced by polar residues. This study provides a template to drive the development of future BoNT therapeutic molecules centered on assessing the natural subtype variations in receptor-binding that appears to be one of the principal stages driving toxicity.
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Affiliation(s)
- Jonathan R. Davies
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden;
| | - Geoffrey Masuyer
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden;
- Department of Pharmacy and Pharmacology, Centre for Therapeutic Innovation, University of Bath, Bath BA2 7AY, UK
- Correspondence: (G.M.); (P.S.)
| | - Pål Stenmark
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden;
- Department of Experimental Medical Science, Lund University, SE-221 00 Lund, Sweden
- Correspondence: (G.M.); (P.S.)
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Kohda T, Nakamura K, Hosomi K, Torii Y, Kozaki S, Mukamoto M. Characterization of the functional activity of botulinum neurotoxin subtype B6. Microbiol Immunol 2018; 61:482-489. [PMID: 28898517 DOI: 10.1111/1348-0421.12540] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 08/30/2017] [Accepted: 09/07/2017] [Indexed: 12/01/2022]
Abstract
Clostridium botulinum produces the highly potent neurotoxin, botulinum neurotoxin (BoNT), which is classified into seven serotypes (A-G); the subtype classification is confirmed by the diversity of amino acid sequences among the serotypes. BoNT from the Osaka05 strain is associated with type B infant botulism and has been classified as BoNT/B subtype B6 (BoNT/B6) by phylogenetic analysis and the antigenicity of its C-terminal heavy chain (HC ) domain. However, the molecular bases for its properties, including its potency, are poorly understood. In this study, BoNT/B6 holotoxin was purified and the biological activity and receptor binding activity of BoNT/B6 compared with those of the previously-characterized BoNT/B1 and BoNT/B2 subtypes. The derivative BoNT/B6 was found to be already nicked and in an activated form, indicating that endogenous protease production may be higher in this strain than in the other two strains. BoNT/B1 exhibited the greatest lethal activity in mice, followed by BoNT/B6, which is consistent with the sensitivity of PC12 cells. No significant differences were seen in the enzymatic activities of the BoNT/Bs against their substrate. HC /B1 and HC /B6 exhibited similar binding affinities to synaptotagmin II (SytII), which is a specific protein receptor for BoNT/B. Binding to the SytII/ganglioside complex is functionally related to the toxic action; however, the receptor recognition sites are conserved. These results suggest that the distinct characteristics and differences in biological sensitivity of BoNT/B6 may be attributable to the function of its Hc .domain.
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Affiliation(s)
- Tomoko Kohda
- Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Rinkuouraikita, Izumisano, 598-8531 Osaka, Japan
| | - Keiji Nakamura
- Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Rinkuouraikita, Izumisano, 598-8531 Osaka, Japan
| | - Koji Hosomi
- Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Rinkuouraikita, Izumisano, 598-8531 Osaka, Japan
| | - Yasushi Torii
- Department of Animal Science, Tokyo University of Agriculture, Funako, Atsugi, 243-0034 Kanagawa, Japan
| | - Shunji Kozaki
- Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Rinkuouraikita, Izumisano, 598-8531 Osaka, Japan
| | - Masafumi Mukamoto
- Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Rinkuouraikita, Izumisano, 598-8531 Osaka, Japan
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The binding of botulinum neurotoxins to different peripheral neurons. Toxicon 2017; 147:27-31. [PMID: 29042309 DOI: 10.1016/j.toxicon.2017.10.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 09/21/2017] [Accepted: 10/13/2017] [Indexed: 11/22/2022]
Abstract
Botulinum neurotoxins are the most potent toxins known. The double receptor binding modality represents one of the most significant properties of botulinum neurotoxins and largely accounts for their incredible potency and lethality. Despite the high affinity and the very specific binding, botulinum neurotoxins are versatile and multi-tasking toxins. Indeed they are able to act both at the somatic and at the autonomic nervous system. In spite of the preference for cholinergic nerve terminals botulinum neurotoxins have been shown to inhibit to some extent also the noradrenergic postganglionic sympathetic nerve terminals and the afferent nerve terminals of the sensory neurons inhibiting the release of neuropeptides and glutamate, which are responsible of nociception. Therefore, there is increasing evidence that the therapeutic effect in both motor and autonomic disorders is based on a complex mode of botulinum neurotoxin action modulating the activity of efferent as well as afferent nerve fibres.
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Identification and characterization of a novel botulinum neurotoxin. Nat Commun 2017; 8:14130. [PMID: 28770820 PMCID: PMC5543303 DOI: 10.1038/ncomms14130] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 12/02/2016] [Indexed: 12/19/2022] Open
Abstract
Botulinum neurotoxins are known to have seven serotypes (BoNT/A-G). Here we report a new BoNT serotype, tentatively named BoNT/X, which has the lowest sequence identity with other BoNTs and is not recognized by antisera against known BoNTs. Similar to BoNT/B/D/F/G, BoNT/X cleaves vesicle-associated membrane proteins (VAMP) 1, 2 and 3, but at a novel site (Arg66-Ala67 in VAMP2). Remarkably, BoNT/X is the only toxin that also cleaves non-canonical substrates VAMP4, VAMP5 and Ykt6. To validate its activity, a small amount of full-length BoNT/X was assembled by linking two non-toxic fragments using a transpeptidase (sortase). Assembled BoNT/X cleaves VAMP2 and VAMP4 in cultured neurons and causes flaccid paralysis in mice. Thus, BoNT/X is a novel BoNT with a unique substrate profile. Its discovery posts a challenge to develop effective countermeasures, provides a novel tool for studying intracellular membrane trafficking, and presents a new potential therapeutic toxin for modulating secretions in cells.
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Rummel A. Two Feet on the Membrane: Uptake of Clostridial Neurotoxins. Curr Top Microbiol Immunol 2016; 406:1-37. [PMID: 27921176 DOI: 10.1007/82_2016_48] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
The extraordinary potency of botulinum neurotoxins (BoNT) and tetanus neurotoxin (TeNT) is mediated by their high neurospecificity, targeting peripheral cholinergic motoneurons leading to flaccid and spastic paralysis, respectively, and successive respiratory failure. Complex polysialo gangliosides accumulate BoNT and TeNT on the plasma membrane. The ganglioside binding in BoNT/A, B, E, F, G, and TeNT occurs via a conserved ganglioside-binding pocket within the most carboxyl-terminal 25 kDa domain HCC, whereas BoNT/C, DC, and D display here two different ganglioside binding sites. This enrichment step facilitates subsequent binding of BoNT/A, B, DC, D, E, F, and G to the intraluminal domains of the synaptic vesicle glycoprotein 2 (SV2) isoforms A-C and synaptotagmin-I/-II, respectively. Whereas an induced α-helical 20-mer Syt peptide binds via side chain interactions to the tip of the HCC domain of BoNT/B, DC and G, the preexisting, quadrilateral β-sheet helix of SV2C-LD4 binds the clinically most relevant serotype BoNT/A mainly through backbone-backbone interactions at the interface of HCC and HCN. In addition, the conserved, complex N559-glycan branch of SV2C establishes extensive interactions with BoNT/A resulting in delayed dissociation providing BoNT/A more time for endocytosis into synaptic vesicles. An analogous interaction occurs between SV2A/B and BoNT/E. Altogether, the nature of BoNT-SV2 recognition clearly differs from BoNT-Syt. Subsequently, the synaptic vesicle is recycled and the bound neurotoxin is endocytosed. Acidification of the vesicle lumen triggers membrane insertion of the translocation domain, pore formation, and finally translocation of the enzymatically active light chain into the neuronal cytosol to halt release of neurotransmitters.
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Affiliation(s)
- Andreas Rummel
- Institut Für Toxikologie, Medizinische Hochschule Hannover, 30623, Hannover, Germany.
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Rummel A. The long journey of botulinum neurotoxins into the synapse. Toxicon 2015; 107:9-24. [PMID: 26363288 DOI: 10.1016/j.toxicon.2015.09.009] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 08/27/2015] [Accepted: 09/08/2015] [Indexed: 01/09/2023]
Abstract
Botulinum neurotoxins (BoNT) cause the disease botulism, a flaccid paralysis of the muscle. They are also very effective, widely used medicines applied locally in sub-nanogram quantities. BoNTs are released together with several non-toxic, associated proteins as progenitor toxin complexes (PCT) by Clostridium botulinum to become highly potent oral poisons ingested via contaminated food. They block the neurotransmission in susceptible animals and humans already in nanogram quantities due to their specific ability to enter motoneurons and to cleave only selected neuronal proteins involved in neuroexocytosis. BoNTs have developed a sophisticated strategy to passage the gastrointestinal tract and to be absorbed in the intestine of the host to finally attack neurons. A non-toxic non-hemagglutinin (NTNHA) forms a binary complex with BoNT to protect it from gastrointestinal degradation. This binary M-PTC is one component of the bi-modular 14-subunit ∼760 kDa large progenitor toxin complex. The other component is the structurally and functionally independent dodecameric hemagglutinin (HA) complex which facilitates the absorption on the intestinal epithelium by glycan binding. Subsequent to its transcytosis the HA complex disrupts the tight junction of the intestinal barrier from the basolateral side by binding to E-cadherin. Now, the L-PTC can also enter the circulation by paracellular routes in much larger quantities. From here, the dissociated BoNTs reach the neuromuscular junction and accumulate via interaction with polysialo gangliosides, complex glycolipids, on motoneurons at the neuromuscular junction. Subsequently, additional specific binding to luminal segments of synaptic vesicles proteins like SV2 and synaptotagmin leads to their uptake. Finally, the neurotoxins shut down the synaptic vesicle cycle, which they had exploited before to enter their target cells, via specific cleavage of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins, which constitute the core components of the cellular membrane fusion machinery.
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Affiliation(s)
- Andreas Rummel
- Institut für Toxikologie, Medizinische Hochschule Hannover, 30623 Hannover, Germany.
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9
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Hosomi K, Sakaguchi Y, Kohda T, Gotoh K, Motooka D, Nakamura S, Umeda K, Iida T, Kozaki S, Mukamoto M. Complete nucleotide sequence of a plasmid containing the botulinum neurotoxin gene in Clostridium botulinum type B strain 111 isolated from an infant patient in Japan. Mol Genet Genomics 2014; 289:1267-74. [PMID: 25149145 DOI: 10.1007/s00438-014-0887-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 07/05/2014] [Indexed: 12/26/2022]
Abstract
Botulinum neurotoxins (BoNTs) are highly potent toxins that are produced by Clostridium botulinum. We determined the complete nucleotide sequence of a plasmid containing the botulinum neurotoxin gene in C. botulinum type B strain 111 in order to obtain an insight into the toxigenicity and evolution of the bont gene in C. botulinum. Group I C. botulinum type B strain 111 was isolated from the first case of infant botulism in Japan in 1995. In previous studies, botulinum neurotoxin subtype B2 (BoNT/B2) produced by strain 111 exhibited different antigenic properties from those of authentic BoNT/B1 produced by strain Okra. We have recently shown that the isolates of strain 111 that lost toxigenicity were cured of the plasmid containing the bont/B2 gene. In the present study, the plasmid (named pCB111) was circular 265,575 bp double-stranded DNA and contained 332 predicted open reading frames (ORFs). 85 gene products of these ORFs could be functionally assigned on the basis of sequence homology to known proteins. The bont/B2 complex genes were located on pCB111 and some gene products may be involved in the conjugative plasmid transfer and horizontal transfer of bont genes. pCB111 was similar to previously identified plasmids containing bont/B1, /B5, or/A3 complex genes in other group I C. botulinum strains. It was suggested that these plasmids had been derived from a common ancestor and had played important roles for the bont gene transfer between C. botulinum.
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Affiliation(s)
- Koji Hosomi
- Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-58 Rinku Orai Kita, Izumisano, Osaka, 598-8531, Japan
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Popoff MR, Bouvet P. Genetic characteristics of toxigenic Clostridia and toxin gene evolution. Toxicon 2013; 75:63-89. [DOI: 10.1016/j.toxicon.2013.05.003] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 04/30/2013] [Accepted: 05/08/2013] [Indexed: 12/14/2022]
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Dolimbek BZ, Steward LE, Aoki KR, Atassi MZ. Location of the synaptosome-binding regions on botulinum neurotoxin B. Biochemistry 2011; 51:316-28. [PMID: 22146011 DOI: 10.1021/bi201322c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The regions of botulinum neurotoxin B (BoNT/B) involved in binding to mouse brain synaptosomes (snps) were localized. Sixty 19-residue overlapping peptides (peptide C31 consisted of 24 residues) encompassing BoNT/B H chain (residues 442-1291) were synthesized and used to inhibit binding of (125)I-labeled BoNT/B to snps. Synaptosome-binding regions were noncompeting and existed on both H(N) and H(C) domains of neurotoxin. At 37 °C, inhibitory activities on H(N) resided, in decreasing order, in peptides 638-656 (26.7%), 596-614 (18.2%), 512-530 (13.9%), 778-796 (13.8%), and 526-544 (11.6%). On H(C), activity resided in decreasing order in peptides 1170-1188 (44.6%), 1128-1146 (21.6%), 1184-1202 (18.6%), 1156-1174 (13.0%), 946-964 (11.8%), 1114-1132 (11.2%), 1100-1118 (6.2%), 876-894 (6.1%), 1268-1291 (4.6%), and 1226-1244 (4.3%). The 45 remaining H(N) and H(C) peptides had no activity. At 4 °C, peptide C24 (1170-1188) remained quite active (inhibiting, 31.2%), while activities of peptides N15, C21, and C25 were little under 10%. The snp-binding regions contained sites that bind synaptotagmin II and gangliosides. Despite the low degree of sequence homology, BoNT/B and BoNT/A display significant structural homology and appeared to bind in part to the same snp-binding regions. Binding of each labeled toxin to snps was inhibited ~50% by the other toxin, 70-72% by its correlate H(C), and by the H(C) of the other toxin [29% (BoNT/A by H(C) of B) or 32% (BoNT/B by H(C) of A)]. In the three-dimensional structure of BoNT/B, the greater part of H(C), one H(N) face, and part of the belt on the same side interact with snps. Thus, BoNT/B binds to snps through the H(C) head and employs regions on one H(N) face and the belt, reserving flexibility for the belt's unbound part to release the light chain. Most snp-binding regions coincide or overlap with blocking antibody (Ab)-binding regions explaining how such Abs prevent BoNT/B toxicity.
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Affiliation(s)
- Behzod Z Dolimbek
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, United States
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Genetic characterization of Clostridium botulinum associated with type B infant botulism in Japan. J Clin Microbiol 2009; 47:2720-8. [PMID: 19571018 DOI: 10.1128/jcm.00077-09] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 15 proteolytic Clostridium botulinum type B strains, including 3 isolates associated with infant botulism in Japan, were genetically characterized by phylogenetic analysis of boNT/B gene sequences, genotyping, and determination of the boNT/B gene location by using pulsed-field gel electrophoresis (PFGE) for molecular epidemiological analysis of infant botulism in Japan. Strain Osaka05, isolated from a case in 2005, showed a unique boNT/B gene sequence and was considered to be a new BoNT/B subtype by phylogenetic analysis. Strain Osaka06, isolated from a case in 2006, was classified as the B2 subtype, the same as strain 111, isolated from a case in 1995. The five isolates associated with infant botulism in the United States were classified into the B1 subtype. Isolates from food samples in Japan were divided into the B1 and the B2 subtypes, although no relation with infant botulism was shown by PFGE genotyping. The results of PFGE and Southern blot hybridization with undigested DNA suggested that the boNT/B gene is located on large plasmids (approximately 150 kbp, 260 kbp, 275 kbp, or 280 kbp) in five strains belonging to three BoNT/B subtypes from various sources. The botulinum neurotoxin (BoNT) of Osaka05 was suggested to have an antigenicity different from the antigenicities of BoNT/B1 and BoNT/B2 by a sandwich enzyme-linked immunosorbent assay with the recombinant BoNT/B-C-terminal domain. We established a multiplex PCR assay for BoNT/B subtyping which will be useful for epidemiological studies of type B strains and the infectious diseases that they cause.
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Novel Clostridium botulinum toxin gene arrangement with subtype A5 and partial subtype B3 botulinum neurotoxin genes. J Clin Microbiol 2009; 47:2349-50. [PMID: 19420169 DOI: 10.1128/jcm.00799-09] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Abstract
Tetanus neurotoxin and botulinum neurotoxins are the causative agents of tetanus and botulism. They block the release of neurotransmitters from synaptic vesicles in susceptible animals and man and act in nanogram quantities because of their ability to specifically attack motoneurons. They developed an ingenious strategy to enter neurons. This involves a concentration step via complex polysialo gangliosides at the plasma membrane and the uptake and ride in recycling synaptic vesicles initiated by binding to a specific protein receptor. Finally, the neurotoxins shut down the synaptic vesicle cycle, which they had misused before to enter their target cells, via specific cleavage of protein core components of the cellular membrane fusion machinery. The uptake of four out of seven known botulinum neurotoxins into synaptic vesicles has been demonstrated to rely on binding to intravesicular segments of the synaptic vesicle proteins synaptotagmin or synaptic vesicle protein 2. This review summarizes the present knowledge about the cell receptor molecules and the mode of toxin-receptor interaction that enables the toxins' sophisticated access to their site of action.
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Affiliation(s)
- Thomas Binz
- Institut für Biochemie, Medizinische Hochschule Hannover, Hannover, Germany.
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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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Tsukamoto K, Kozai Y, Ihara H, Kohda T, Mukamoto M, Tsuji T, Kozaki S. Identification of the receptor-binding sites in the carboxyl-terminal half of the heavy chain of botulinum neurotoxin types C and D. Microb Pathog 2008; 44:484-93. [PMID: 18242046 DOI: 10.1016/j.micpath.2007.12.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 12/11/2007] [Accepted: 12/14/2007] [Indexed: 10/22/2022]
Abstract
Botulinum neurotoxin (BoNT) binds to presynaptic neuronal cells and blocks neurotransmitter release. The carboxyl-terminal half of the heavy chain (H(C)) of the neurotoxin recognizes its specific receptor on the plasma membrane. We have previously demonstrated that BoNT/C binds to gangliosides GD1b and GT1b under physiological conditions, while BoNT/D interacts with phosphatidylethanolamine (PE). Here we report that the recognition sites for gangliosides and PE are present in the carboxyl-terminal domain of H(C). Chimeric mutants and site-directed mutants of BoNT/C-H(C) and BoNT/D-H(C) were generated and their binding activities evaluated. The chimeric H(C) that consisted of the amino-terminal half of BoNT/D-H(C) and the carboxyl-terminal half of BoNT/C-H(C) possessed activity similar to the authentic BoNT/C-H(C), suggesting that the carboxyl-terminal region of H(C) is involved in the receptor recognition of BoNT/C. Moreover, analysis using site-directed mutants indicated that the peptide motif W(1257)Ycdots, three dots, centeredG(1270)cdots, three dots, centeredH(1282) plays an important role in the interaction between BoNT/C and gangliosides. In contrast, we revealed that two lysine residues of BoNT/D-H(C) are involved in the formation of the critical binding site for receptor binding.
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Affiliation(s)
- Kentaro Tsukamoto
- Department of Microbiology, Fujita Health University School of Medicine, Toyoake, Aichi 4701192, Japan
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Kohda T, Ihara H, Seto Y, Tsutsuki H, Mukamoto M, Kozaki S. Differential contribution of the residues in C-terminal half of the heavy chain of botulinum neurotoxin type B to its binding to the ganglioside GT1b and the synaptotagmin 2/GT1b complex. Microb Pathog 2007; 42:72-9. [PMID: 17188834 DOI: 10.1016/j.micpath.2006.10.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Accepted: 10/31/2006] [Indexed: 10/23/2022]
Abstract
Clostridium botulinum type B neurotoxin was effectively bound to synaptotagmin 2 (Stg2) associated with ganglioside GT1b, however, the molecular interaction between the neurotoxin and the Stg2/GT1b complex has not been identified. Previously, we found that infant botulism-related strain 111 generated a low activity of the neurotoxin (111/NT), which differed in some amino acid residues, especially in the carboxyl terminal half of the heavy chain (H(C)), from the original neurotoxin of strain Okra (Okra/NT) associated with a food-borne botulism. In this study, we evaluated the binding capabilities of site-directed mutants of Okra/H(C) to the Stg2/GT1b complex and to GT1b alone, and investigated the relationship between the toxic action and receptor binding. Replacement of K1187 and E1190 with glutamic acid and lysine, respectively, which substituted for the 111/NT residues, caused a reduction of binding affinity to the Stg2/GT1b complex, suggesting that both these residues contribute to the different binding affinity between Okra/NT and 111/NT. Substitution of four residues, H1240, S1259, W1261 and Y1262, which form a ganglioside pocket, drastically decreased the binding of H(C) to the Stg2/GT1b complex and to GT1b. Mutation in the residues, K1186, E1189, K1191 and K1260 reduced the binding of H(C) to GT1b alone, but not to the Stg2/GT1b complex. Analyses of effects of mutant toxins on toxicity of BoNT/B to cerebellar granule cells suggest the association of cell toxicity with binding to Stg2/GT1b complex but not that to GT1b alone.
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Affiliation(s)
- Tomoko Kohda
- Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
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Rummel A, Eichner T, Weil T, Karnath T, Gutcaits A, Mahrhold S, Sandhoff K, Proia RL, Acharya KR, Bigalke H, Binz T. Identification of the protein receptor binding site of botulinum neurotoxins B and G proves the double-receptor concept. Proc Natl Acad Sci U S A 2007; 104:359-64. [PMID: 17185412 PMCID: PMC1716154 DOI: 10.1073/pnas.0609713104] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Indexed: 11/18/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) cause muscle paralysis by selectively cleaving core components of the vesicular fusion machinery within motoneurons. Complex gangliosides initially bind into a pocket that is conserved among the seven BoNTs and tetanus neurotoxin. Productive neurotoxin uptake also requires protein receptors. The interaction site of the protein receptor within the neurotoxin is currently unknown. We report the identification and characterization of the protein receptor binding site of BoNT/B and BoNT/G. Their protein receptors, synaptotagmins I and II, bind to a pocket at the tip of their H(CC) (C-terminal domain of the C-terminal fragment of the heavy chain) that corresponds to the unique second carbohydrate binding site of tetanus neurotoxin, the sialic acid binding site. Substitution of amino acids in this region impaired binding to synaptotagmins and drastically decreased toxicity at mouse phrenic nerve preparations; CD-spectroscopic analyses evidenced that the secondary structure of the mutated neurotoxins was unaltered. Deactivation of the synaptotagmin binding site by single mutations led to virtually inactive BoNT/B and BoNT/G when assayed at phrenic nerve preparations of complex-ganglioside-deficient mice. Analogously, a BoNT B mutant with deactivated ganglioside and synaptotagmin binding sites lacked appreciable activity at wild-type mouse phrenic nerve preparations. Thus, these data exclude relevant contributions of any cell surface molecule other than one ganglioside and one protein receptor to the entry process of BoNTs, which substantiates the double-receptor concept. The molecular characterization of the synaptotagmin binding site provides the basis for designing a novel class of potent binding inhibitors.
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Affiliation(s)
- Andreas Rummel
- *Institut für Biochemie, OE 4310, and
- Institut für Toxikologie, OE 5340, Medizinische Hochschule Hannover, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - Timo Eichner
- Institut für Toxikologie, OE 5340, Medizinische Hochschule Hannover, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - Tanja Weil
- Merz Pharmaceuticals GmbH, Eckenheimer Landstrasse 100, 60318 Frankfurt am Main, Germany
| | | | - Aleksandrs Gutcaits
- Merz Pharmaceuticals GmbH, Eckenheimer Landstrasse 100, 60318 Frankfurt am Main, Germany
| | | | - Konrad Sandhoff
- Kekule-Institut für Organische Chemie und Biochemie der Universität Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany
| | - Richard L. Proia
- Genetics of Development and Disease Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892; and
| | - K. Ravi Acharya
- **Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
| | - Hans Bigalke
- Institut für Toxikologie, OE 5340, Medizinische Hochschule Hannover, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
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Hill KK, Smith TJ, Helma CH, Ticknor LO, Foley BT, Svensson RT, Brown JL, Johnson EA, Smith LA, Okinaka RT, Jackson PJ, Marks JD. Genetic diversity among Botulinum Neurotoxin-producing clostridial strains. J Bacteriol 2006; 189:818-32. [PMID: 17114256 PMCID: PMC1797315 DOI: 10.1128/jb.01180-06] [Citation(s) in RCA: 310] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clostridium botulinum is a taxonomic designation for many diverse anaerobic spore-forming rod-shaped bacteria that have the common property of producing botulinum neurotoxins (BoNTs). The BoNTs are exoneurotoxins that can cause severe paralysis and death in humans and other animal species. A collection of 174 C. botulinum strains was examined by amplified fragment length polymorphism (AFLP) analysis and by sequencing of the 16S rRNA gene and BoNT genes to examine the genetic diversity within this species. This collection contained representatives of each of the seven different serotypes of botulinum neurotoxins (BoNT/A to BoNT/G). Analysis of the16S rRNA gene sequences confirmed previous identifications of at least four distinct genomic backgrounds (groups I to IV), each of which has independently acquired one or more BoNT genes through horizontal gene transfer. AFLP analysis provided higher resolution and could be used to further subdivide the four groups into subgroups. Sequencing of the BoNT genes from multiple strains of serotypes A, B, and E confirmed significant sequence variation within each serotype. Four distinct lineages within each of the BoNT A and B serotypes and five distinct lineages of serotype E strains were identified. The nucleotide sequences of the seven toxin genes of the serotypes were compared and showed various degrees of interrelatedness and recombination, as was previously noted for the nontoxic nonhemagglutinin gene, which is linked to the BoNT gene. These analyses contribute to the understanding of the evolution and phylogeny within this species and assist in the development of improved diagnostics and therapeutics for the treatment of botulism.
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Affiliation(s)
- K K Hill
- Bioscience, Theoretical Divisions, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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Smith TJ, Lou J, Geren IN, Forsyth CM, Tsai R, Laporte SL, Tepp WH, Bradshaw M, Johnson EA, Smith LA, Marks JD. Sequence variation within botulinum neurotoxin serotypes impacts antibody binding and neutralization. Infect Immun 2005; 73:5450-7. [PMID: 16113261 PMCID: PMC1231122 DOI: 10.1128/iai.73.9.5450-5457.2005] [Citation(s) in RCA: 223] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The botulinum neurotoxins (BoNTs) are category A biothreat agents which have been the focus of intensive efforts to develop vaccines and antibody-based prophylaxis and treatment. Such approaches must take into account the extensive BoNT sequence variability; the seven BoNT serotypes differ by up to 70% at the amino acid level. Here, we have analyzed 49 complete published sequences of BoNTs and show that all toxins also exhibit variability within serotypes ranging between 2.6 and 31.6%. To determine the impact of such sequence differences on immune recognition, we studied the binding and neutralization capacity of six BoNT serotype A (BoNT/A) monoclonal antibodies (MAbs) to BoNT/A1 and BoNT/A2, which differ by 10% at the amino acid level. While all six MAbs bound BoNT/A1 with high affinity, three of the six MAbs showed a marked reduction in binding affinity of 500- to more than 1,000-fold to BoNT/A2 toxin. Binding results predicted in vivo toxin neutralization; MAbs or MAb combinations that potently neutralized A1 toxin but did not bind A2 toxin had minimal neutralizing capacity for A2 toxin. This was most striking for a combination of three binding domain MAbs which together neutralized >40,000 mouse 50% lethal doses (LD(50)s) of A1 toxin but less than 500 LD(50)s of A2 toxin. Combining three MAbs which bound both A1 and A2 toxins potently neutralized both toxins. We conclude that sequence variability exists within all toxin serotypes, and this impacts monoclonal antibody binding and neutralization. Such subtype sequence variability must be accounted for when generating and evaluating diagnostic and therapeutic antibodies.
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Affiliation(s)
- T J Smith
- Toxinology Division, USAMRIID, Frederick, Maryland, USA
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Tsukamoto K, Kohda T, Mukamoto M, Takeuchi K, Ihara H, Saito M, Kozaki S. Binding of Clostridium botulinum type C and D neurotoxins to ganglioside and phospholipid. Novel insights into the receptor for clostridial neurotoxins. J Biol Chem 2005; 280:35164-71. [PMID: 16115873 DOI: 10.1074/jbc.m507596200] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Clostridium botulinum neurotoxins (BoNTs) act on nerve endings to block acetylcholine release. Their potency is due to their enzymatic activity and selective high affinity binding to neurons. Although there are many pieces of data available on the receptor for BoNT, little attempt has been made to characterize the receptors for BoNT/C and BoNT/D. For this purpose, we prepared the recombinant carboxyl-terminal domain of the heavy chain (H(C)) and then examined its binding capability to rat brain synaptosomes treated with enzymes and heating. Synaptosomes treated with proteinase K or heating retained binding capability to both H(C)/C and H(C)/D, suggesting that a proteinaceous substance does not constitute the receptor component. We next performed a thin layer chromatography overlay assay of H(C) with a lipid extract of synaptosomes. Under physiological or higher ionic strengths, H(C)/C bound to gangliosides GD1b and GT1b. These data are in accord with results showing that neuraminidase and endoglycoceramidase treatment decreased H(C)/C binding to synaptosomes. On the other hand, H(C)/D interacted with phosphatidylethanolamine but not with any ganglioside. Using cerebellar granule cells obtained from GM3 synthase knock-out mice, we found that BoNT/C did not elicit a toxic effect but that BoNT/D still inhibited glutamate release to the same extent as in granule cells from wild type mice. These observations suggested that BoNT/C recognized GD1b and GT1b as functional receptors, whereas BoNT/D induced toxicity in a ganglioside-independent manner, possibly through binding to phosphatidylethanolamine. Our results provide novel insights into the receptor for clostridial neurotoxin.
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Affiliation(s)
- Kentaro Tsukamoto
- Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Japan
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Abstract
Biologic toxins are molecules produced by living organisms that are poisonous to other species, such as humans. Some biologic toxins are so potent and relatively easy to produce that they have been classified as biothreat agents. These include the botulinum neurotoxins, ricin, staphylococcal enterotoxin B, and Clostridium perfringens epsilon toxin. This article focuses on these four biothreat toxins and their medical aspects. The majority of the article is spent on the botulinum neurotoxins, because these are the most poisonous substances known and are the only toxins classified as Category A threat agents-the highest level of threat agent. The remainder of the article is devoted to sections on the other three biothreat toxins: ricin, staphylococcal enterotoxin B, and C perfringens epsilon toxin.
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Affiliation(s)
- James D Marks
- Department of Anesthesia and Perioperative Care, University of California San Francisco, San Francisco General Hospital, Room 3C38, 1001 Potrero Avenue, San Francisco, CA 94110, USA.
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Lalli G, Bohnert S, Deinhardt K, Verastegui C, Schiavo G. The journey of tetanus and botulinum neurotoxins in neurons. Trends Microbiol 2003; 11:431-7. [PMID: 13678859 DOI: 10.1016/s0966-842x(03)00210-5] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Anaerobic bacteria of the genus Clostridia are a major threat to human and animal health, being responsible for pathologies ranging from food poisoning to gas gangrene. In each of these, the production of sophisticated exotoxins is the main cause of disease. The most powerful clostridial toxins are tetanus and botulinum neurotoxins, the causative agents of tetanus and botulism. They are structurally organized into three domains endowed with distinct functions: high affinity binding to neurons, membrane translocation and specific cleavage of proteins controlling neuroexocytosis. Recent discoveries regarding the mechanism of membrane recruitment and sorting of these neurotoxins within neurons make them ideal tools to uncover essential aspects of neuronal physiology in health and disease.
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Affiliation(s)
- Giovanna Lalli
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK.
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