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Gutiérrez-Arnal J, Marín C. The Latent Threat in Wild Birds: Clostridium botulinum. Vet Sci 2024; 11:36. [PMID: 38250942 PMCID: PMC10818396 DOI: 10.3390/vetsci11010036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 01/14/2024] [Accepted: 01/15/2024] [Indexed: 01/23/2024] Open
Abstract
Avian botulism caused by Clostridium botulinum emerged in 1910, affecting birds across North America, leading to severe outbreaks exacerbated by climate change, decreasing water levels, and inadequate wastewater management. While deadly for birds, its epidemiological impact on humans and other animals remains limited. Despite its significance, understanding and controlling the disease remain challenging. This review delves into the pathogen's epidemiology in wild bird populations, exploring the transmission, pathogenicity, clinical symptoms, diagnosis and treatment. The disease's growing concern in wild birds relates to the bacterium's adaptability and expansive spread, evident through genetic similarities among strains across countries. Outbreaks are influenced by environmental factors such as temperature and soil characteristics. Wild birds inadvertently transmit the bacterium, perpetuating the cycle through carcasses and flies. Some species suffer severely, while others, like scavengers, show resistance. Understanding disease mechanisms, involving potential toxin ingestion or internal production, remains ongoing. Clinical signs vary, affecting diverse bird orders. Diagnostic methods evolve, with treatment success varying among affected populations. Prevention and surveillance take precedence due to treatment challenges, emphasising population-based strategies and preventive measures to manage the widespread presence of C. botulinum.
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Affiliation(s)
- Josep Gutiérrez-Arnal
- Facultad de Veterinaria, Universidad Cardenal Herrera-CEU, CEU Universities, Calle Santiago Ramón y Cajal 20, 45115 Valencia, Alfara del Patriarca, Spain;
| | - Clara Marín
- Departamento de Producción y Sanidad Animal, Salud Pública Veterinaria y Ciencia y Tecnología de los Alimentos, Facultad de Veterinaria, Instituto de Ciencias Biomédicas, Universidad Cardenal Herrera-CEU, CEU Universities, Calle Santiago Ramón y Cajal 20, 45115 Valencia, Alfara del Patriarca, Spain
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Harris RA, Flint A, Blondin Brosseau M, Weedmark K, Austin JW. Complete genomes of Clostridium botulinum type B(F) isolates associated with a 1995 foodborne botulism outbreak from commercial pâté reveals a recombination event disrupting the ntnh gene. Microb Genom 2024; 10:001169. [PMID: 38175697 PMCID: PMC10868621 DOI: 10.1099/mgen.0.001169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 12/08/2023] [Indexed: 01/05/2024] Open
Abstract
Foodborne botulism is a neuroparalytic disease caused by ingestion of foods contaminated with botulinum neurotoxin (BoNT), produced by Clostridium botulinum. In 1995 a husband and wife from Québec, Canada, were hospitalized for several months with prolonged muscle paralysis after ingesting a commercial pâté de campagne. Examination of faecal samples from both patients and the pâté produced viable Group I (proteolytic) C. botulinum type B from each of the three samples. Whole genome sequencing revealed that all three isolates contain identical bont/B5 and bont/F2 genes encoded on a plasmid. Both faecal isolate genomes were identical in chromosome and plasmid length, as well as gene content. The genome of the pâté isolate was nearly identical to that of the faecal isolates with the notable difference of a missing 13-gene insertion on the bont/B5 cluster disrupting the ntnh gene. Examination of the insertion revealed several mobile genetic elements that participate in recombination.
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Affiliation(s)
| | - Annika Flint
- Bureau of Microbial Hazards, Health Canada, Ottawa, Ontario, Canada
| | | | - Kelly Weedmark
- Bureau of Microbial Hazards, Health Canada, Ottawa, Ontario, Canada
| | - John W. Austin
- Bureau of Microbial Hazards, Health Canada, Ottawa, Ontario, Canada
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3
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Rawson AM, Dempster AW, Humphreys CM, Minton NP. Pathogenicity and virulence of Clostridium botulinum. Virulence 2023; 14:2205251. [PMID: 37157163 PMCID: PMC10171130 DOI: 10.1080/21505594.2023.2205251] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023] Open
Abstract
Clostridium botulinum, a polyphyletic Gram-positive taxon of bacteria, is classified purely by their ability to produce botulinum neurotoxin (BoNT). BoNT is the primary virulence factor and the causative agent of botulism. A potentially fatal disease, botulism is classically characterized by a symmetrical descending flaccid paralysis, which is left untreated can lead to respiratory failure and death. Botulism cases are classified into three main forms dependent on the nature of intoxication; foodborne, wound and infant. The BoNT, regarded as the most potent biological substance known, is a zinc metalloprotease that specifically cleaves SNARE proteins at neuromuscular junctions, preventing exocytosis of neurotransmitters, leading to muscle paralysis. The BoNT is now used to treat numerous medical conditions caused by overactive or spastic muscles and is extensively used in the cosmetic industry due to its high specificity and the exceedingly small doses needed to exert long-lasting pharmacological effects. Additionally, the ability to form endospores is critical to the pathogenicity of the bacteria. Disease transmission is often facilitated via the metabolically dormant spores that are highly resistant to environment stresses, allowing persistence in the environment in unfavourable conditions. Infant and wound botulism infections are initiated upon germination of the spores into neurotoxin producing vegetative cells, whereas foodborne botulism is attributed to ingestion of preformed BoNT. C. botulinum is a saprophytic bacterium, thought to have evolved its potent neurotoxin to establish a source of nutrients by killing its host.
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Affiliation(s)
- Alexander M Rawson
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The Biodiscovery Institute, The University of Nottingham, Nottingham, UK
| | - Andrew W Dempster
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The Biodiscovery Institute, The University of Nottingham, Nottingham, UK
| | - Christopher M Humphreys
- Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, The Biodiscovery Institute, The University of Nottingham, Nottingham, UK
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Roja B, Saranya S, Chellapandi P. Discovery of novel virulence mechanisms in Clostridium botulinum type A3 using genome-wide analysis. Gene 2023; 869:147402. [PMID: 36972858 DOI: 10.1016/j.gene.2023.147402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 03/01/2023] [Accepted: 03/24/2023] [Indexed: 03/29/2023]
Abstract
OBJECTIVE Clostridium botulinum type A is a neurotoxin-producing, spore-forming anaerobic bacterium that causes botulism in humans. The evolutionary genomic context of this organism is not yet known to understand its molecular virulence mechanisms in the human intestinal tract. Hence, this study aimed to investigate the mechanisms underlying virulence and pathogenesis by comparing the genomic contexts across species, serotypes, and subtypes. METHODS A comparative genomic approach was used to analyze evolutionary genomic relationships, intergenomic distances, syntenic blocks, replication origins, and gene abundance with phylogenomic neighbors. RESULTS Type A strains have shown genomic proximity to group I strains with distinct accessory genes and vary even within subtypes. Phylogenomic data showed that type C and D strains were distantly related to a group I and group II strains. Synthetic plots indicated that orthologous genes might have evolved from Clostridial ancestry to subtype A3 strains, whereas syntonic out-paralogs might have emerged between subtypes A3 and A1 through α-events. Gene abundance analysis revealed the key roles of genes involved in biofilm formation, cell-cell communication, human diseases, and drug resistance compared to the pathogenic Clostridia. Moreover, we identified 43 unique genes in the type A3 genome, of which 29 were involved in the pathophysiological processes and other genes contributed to amino acid metabolism. The C. botulinum type A3 genome contains 14 new virulence proteins that can provide the ability to confer antibiotic resistance, virulence exertion and adherence to host cells, the host immune system, and mobility of extrachromosomal genetic elements. CONCLUSION The results of our study provide insight into the understanding of new virulence mechanisms to discover new therapeutics for the treatment of human diseases caused by type A3 strains.
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Affiliation(s)
- B Roja
- Industrial Systems Biology Lab, Department of Bioinformatics, School of Life Sciences, Bharathidasan University, Tiruchirappalli-620024, Tamil Nadu, India
| | - S Saranya
- Industrial Systems Biology Lab, Department of Bioinformatics, School of Life Sciences, Bharathidasan University, Tiruchirappalli-620024, Tamil Nadu, India
| | - P Chellapandi
- Industrial Systems Biology Lab, Department of Bioinformatics, School of Life Sciences, Bharathidasan University, Tiruchirappalli-620024, Tamil Nadu, India.
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Ma X, Li K, Li F, Su J, Meng W, Sun Y, Sun H, Sun J, Yuan Y, Lin Y, Hu S, Xu X, He Z. Tracing Foodborne Botulism Events Caused by Clostridium botulinum in Xinjiang Province, China, Using a Core Genome Sequence Typing Scheme. Microbiol Spectr 2022; 10:e0116422. [PMID: 36377961 PMCID: PMC9769928 DOI: 10.1128/spectrum.01164-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 10/22/2022] [Indexed: 11/16/2022] Open
Abstract
Foodborne botulism is a rare but life-threatening illness resulting from the action of a potent toxin mainly produced by Clostridium botulinum. It grows in an oxygen-deficient environment and is extremely viable in meat and soy products, making it one of the most virulent bacteria. How to track foodborne botulism events quickly and accurately has become a key issue. Here, we investigated two foodborne botulism events that occurred in Xinjiang in 2019 based on whole-genome sequencing and also successfully traced the relationship between clinical and food C. botulinum isolates using whole-genome core gene markers. All 59 isolates were classified as group I strains. Of the strains isolated in this study, 44 were found to be botulinum toxin A(B), and 15 isolates contained only the toxin B locus. Both the toxin A and B gene segments were located on the chromosome and organized in an ha cluster. Antibiotic resistance and virulence factors were also investigated. A set of 329 universal core gene markers were established using C. botulinum strains from a public database. These core gene markers were applied to the published C. botulinum genomes, and three outbreaks were identified. This work demonstrates that universal core gene markers can be used to trace foodborne botulism events, and we hope that our work will facilitate this effort in future. IMPORTANCE In this study, we analyzed 59 foodborne botulism (FB)-related strains isolated in Xinjiang Province, China. Our findings not only reveal the group classification, neurotoxin locus organization, antibiotic resistance and virulence factors of these strains but also establish a set of core gene markers for tracing foodborne botulism events, which was verified using published genomes. These findings indicate that these gene markers might be used as a potential tracing tool for FB events caused by C. botulinum group I strains, which have relatively stable genomic components.
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Affiliation(s)
- Xin Ma
- Center for Disease Control and Prevention of Xinjiang Uygur Autonomous Region, Urumqi, China
| | - Kexin Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- School of Engineering Medicine, Beihang University, Beijing, China
- Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Interdisciplinary Innovation Institute of Medicine and Engineering, Beihang University, Beijing, China
| | - Fang Li
- Center for Disease Control and Prevention of Xinjiang Uygur Autonomous Region, Urumqi, China
| | - Jing Su
- Center for Disease Control and Prevention of Xinjiang Uygur Autonomous Region, Urumqi, China
| | - Weiwei Meng
- Center for Disease Control and Prevention of Xinjiang Uygur Autonomous Region, Urumqi, China
| | - Yanming Sun
- School of Engineering Medicine, Beihang University, Beijing, China
| | - Hui Sun
- State Key Laboratory for Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, Beijing, China
- National Institute for Communicable Diseases Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Jiazheng Sun
- Criminal Investigation School, People's Public Security University of China, Beijing, China
| | - Yonghe Yuan
- Center for Disease Control and Prevention of Xinjiang Uygur Autonomous Region, Urumqi, China
| | - Yujia Lin
- Center for Disease Control and Prevention of Xinjiang Uygur Autonomous Region, Urumqi, China
| | - Songnian Hu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Xuefang Xu
- State Key Laboratory for Infectious Disease Prevention and Control, Chinese Center for Disease Control and Prevention, Beijing, China
- National Institute for Communicable Diseases Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Zilong He
- School of Engineering Medicine, Beihang University, Beijing, China
- Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Interdisciplinary Innovation Institute of Medicine and Engineering, Beihang University, Beijing, China
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Extensive Genome Exploration of Clostridium botulinum Group III Field Strains. Microorganisms 2021; 9:microorganisms9112347. [PMID: 34835472 PMCID: PMC8624178 DOI: 10.3390/microorganisms9112347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 11/03/2021] [Accepted: 11/10/2021] [Indexed: 11/16/2022] Open
Abstract
In animals, botulism is commonly sustained by botulinum neurotoxin C, D or their mosaic variants, which are produced by anaerobic bacteria included in Clostridium botulinum group III. In this study, a WGS has been applied to a large collection of C. botulinum group III field strains in order to expand the knowledge on these BoNT-producing Clostridia and to evaluate the potentiality of this method for epidemiological investigations. Sixty field strains were submitted to WGS, and the results were analyzed with respect to epidemiological information and compared to published sequences. The strains were isolated from biological or environmental samples collected in animal botulism outbreaks which occurred in Italy from 2007 to 2016. The new sequenced strains belonged to subspecific groups, some of which were already defined, while others were newly characterized, peculiar to Italian strains and contained genomic features not yet observed. This included, in particular, two new flicC types (VI and VII) and new plasmids which widen the known plasmidome of the species. The extensive genome exploration shown in this study improves the C. botulinum and related species classification scheme, enriching it with new strains of rare genotypes and permitting the highest grade of discrimination among strains for forensic and epidemiological applications.
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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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Brunt J, van Vliet AHM, Carter AT, Stringer SC, Amar C, Grant KA, Godbole G, Peck MW. Diversity of the Genomes and Neurotoxins of Strains of Clostridium botulinum Group I and Clostridium sporogenes Associated with Foodborne, Infant and Wound Botulism. Toxins (Basel) 2020; 12:toxins12090586. [PMID: 32932818 PMCID: PMC7551954 DOI: 10.3390/toxins12090586] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 09/02/2020] [Accepted: 09/08/2020] [Indexed: 12/23/2022] Open
Abstract
Clostridium botulinum Group I and Clostridium sporogenes are closely related bacteria responsible for foodborne, infant and wound botulism. A comparative genomic study with 556 highly diverse strains of C. botulinum Group I and C. sporogenes (including 417 newly sequenced strains) has been carried out to characterise the genetic diversity and spread of these bacteria and their neurotoxin genes. Core genome single-nucleotide polymorphism (SNP) analysis revealed two major lineages; C. botulinum Group I (most strains possessed botulinum neurotoxin gene(s) of types A, B and/or F) and C. sporogenes (some strains possessed a type B botulinum neurotoxin gene). Both lineages contained strains responsible for foodborne, infant and wound botulism. A new C. sporogenes cluster was identified that included five strains with a gene encoding botulinum neurotoxin sub-type B1. There was significant evidence of horizontal transfer of botulinum neurotoxin genes between distantly related bacteria. Population structure/diversity have been characterised, and novel associations discovered between whole genome lineage, botulinum neurotoxin sub-type variant, epidemiological links to foodborne, infant and wound botulism, and geographic origin. The impact of genomic and physiological variability on the botulism risk has been assessed. The genome sequences are a valuable resource for future research (e.g., pathogen biology, evolution of C. botulinum and its neurotoxin genes, improved pathogen detection and discrimination), and support enhanced risk assessments and the prevention of botulism.
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Affiliation(s)
- Jason Brunt
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (A.T.C.); (S.C.S.)
- Correspondence: (J.B.); (M.W.P.)
| | - Arnoud H. M. van Vliet
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7AL, UK;
| | - Andrew T. Carter
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (A.T.C.); (S.C.S.)
| | - Sandra C. Stringer
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (A.T.C.); (S.C.S.)
| | - Corinne Amar
- Gastrointestinal Pathogens Unit, National Infection Service, Public Health England, London NW9 5EQ, UK; (C.A.); (K.A.G.); (G.G.)
| | - Kathie A. Grant
- Gastrointestinal Pathogens Unit, National Infection Service, Public Health England, London NW9 5EQ, UK; (C.A.); (K.A.G.); (G.G.)
| | - Gauri Godbole
- Gastrointestinal Pathogens Unit, National Infection Service, Public Health England, London NW9 5EQ, UK; (C.A.); (K.A.G.); (G.G.)
| | - Michael W. Peck
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (A.T.C.); (S.C.S.)
- Correspondence: (J.B.); (M.W.P.)
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Brunt J, van Vliet AHM, Stringer SC, Carter AT, Lindström M, Peck MW. Pan-Genomic Analysis of Clostridium botulinum Group II (Non-Proteolytic C. botulinum) Associated with Foodborne Botulism and Isolated from the Environment. Toxins (Basel) 2020; 12:E306. [PMID: 32397147 PMCID: PMC7291236 DOI: 10.3390/toxins12050306] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 12/21/2022] Open
Abstract
The neurotoxin formed by Clostridium botulinum Group II is a major cause of foodborne botulism, a deadly intoxication. This study aims to understand the genetic diversity and spread of C. botulinum Group II strains and their neurotoxin genes. A comparative genomic study has been conducted with 208 highly diverse C. botulinum Group II strains (180 newly sequenced strains isolated from 16 countries over 80 years, 28 sequences from Genbank). Strains possessed a single type B, E, or F neurotoxin gene or were closely related strains with no neurotoxin gene. Botulinum neurotoxin subtype variants (including novel variants) with a unique amino acid sequence were identified. Core genome single-nucleotide polymorphism (SNP) analysis identified two major lineages-one with type E strains, and the second dominated by subtype B4 strains with subtype F6 strains. This study revealed novel details of population structure/diversity and established relationships between whole-genome lineage, botulinum neurotoxin subtype variant, association with foodborne botulism, epidemiology, and geographical source. Additionally, the genome sequences represent a valuable resource for the research community (e.g., understanding evolution of C. botulinum and its neurotoxin genes, dissecting key aspects of C. botulinum Group II biology). This may contribute to improved risk assessments and the prevention of foodborne botulism.
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Affiliation(s)
- Jason Brunt
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (S.C.S.); (A.T.C.)
| | - Arnoud H. M. van Vliet
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7AL, UK;
| | - Sandra C. Stringer
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (S.C.S.); (A.T.C.)
| | - Andrew T. Carter
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (S.C.S.); (A.T.C.)
| | - Miia Lindström
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, 00014 Helsinki, Finland;
| | - Michael W. Peck
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (S.C.S.); (A.T.C.)
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Martínez-Carranza M, Blasco P, Gustafsson R, Dong M, Berntsson RPA, Widmalm G, Stenmark P. Synaptotagmin Binding to Botulinum Neurotoxins. Biochemistry 2019; 59:491-498. [PMID: 31809018 DOI: 10.1021/acs.biochem.9b00554] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Botulinum neurotoxins (BoNTs) are exceptionally toxic proteins that cause paralysis but are also extensively used as treatment for various medical conditions. Most BoNTs bind two receptors on neuronal cells, namely, a ganglioside and a protein receptor. Differences in the sequence between the protein receptors from different species can impact the binding affinity and toxicity of the BoNTs. Here we have investigated how BoNT/B, /DC, and /G, all three toxins that utilize synaptotagmin I and II (Syt-I and Syt-II, respectively) as their protein receptors, bind to Syt-I and -II of mouse/rat, bovine, and human origin by isothermal titration calorimetry analysis. BoNT/G had the highest affinity for human Syt-I, and BoNT/DC had the highest affinity for bovine Syt-II. As expected, BoNT/B, /DC, and /G showed very low levels of binding to human Syt-II. Furthermore, we carried out saturation transfer difference (STD) and STD-TOCSY NMR experiments that revealed the region of the Syt peptide in direct contact with BoNT/G, which demonstrate that BoNT/G recognizes the Syt peptide in a model similar to that in the established BoNT/B-Syt-II complex. Our analyses also revealed that regions outside the Syt peptide's toxin-binding region are important for the helicity of the peptide and, therefore, the binding affinity.
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Affiliation(s)
| | - Pilar Blasco
- Department of Organic Chemistry , Stockholm University , SE-106 91 Stockholm , Sweden
| | - Robert Gustafsson
- Department of Biochemistry and Biophysics , Stockholm University , SE-106 91 Stockholm , Sweden
| | - Min Dong
- Department of Urology, Boston's Children Hospital, and Department of Microbiology and Immunology and Department of Surgery , Harvard Medical School , Boston , Massachusetts 02115 , United States
| | - Ronnie Per-Arne Berntsson
- Department of Medical Biochemistry and Biophysics , Umeå University , SE-90187 Umeå , Sweden.,Wallenberg Centre for Molecular Medicine , Umeå University , SE-90187 Umeå , Sweden
| | - Göran Widmalm
- Department of Organic Chemistry , Stockholm University , SE-106 91 Stockholm , Sweden
| | - 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
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The orphan germinant receptor protein GerXAO (but not GerX3b) is essential for L-alanine induced germination in Clostridium botulinum Group II. Sci Rep 2018; 8:7060. [PMID: 29728678 PMCID: PMC5935672 DOI: 10.1038/s41598-018-25411-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 04/20/2018] [Indexed: 12/27/2022] Open
Abstract
Clostridium botulinum is an anaerobic spore forming bacterium that produces the potent botulinum neurotoxin that causes a severe and fatal neuro-paralytic disease of humans and animals (botulism). C. botulinum Group II is a psychrotrophic saccharolytic bacterium that forms spores of moderate heat resistance and is a particular hazard in minimally heated chilled foods. Spore germination is a fundamental process that allows the spore to transition to a vegetative cell and typically involves a germinant receptor (GR) that responds to environmental signals. Analysis of C. botulinum Group II genomes shows they contain a single GR cluster (gerX3b), and an additional single gerA subunit (gerXAO). Spores of C. botulinum Group II strain Eklund 17B germinated in response to the addition of L-alanine, but did not germinate following the addition of exogenous Ca2+-DPA. Insertional inactivation experiments in this strain unexpectedly revealed that the orphan GR GerXAO is essential for L-alanine stimulated germination. GerX3bA and GerX3bC affected the germination rate but were unable to induce germination in the absence of GerXAO. No role could be identified for GerX3bB. This is the first study to identify the functional germination receptor of C. botulinum Group II.
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Chellapandi P, Prisilla A. Clostridium botulinum type A-virulome-gut interactions: A systems biology insight. ACTA ACUST UNITED AC 2018. [DOI: 10.1016/j.humic.2018.01.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Nawrocki EM, Bradshaw M, Johnson EA. Botulinum neurotoxin-encoding plasmids can be conjugatively transferred to diverse clostridial strains. Sci Rep 2018; 8:3100. [PMID: 29449580 PMCID: PMC5814558 DOI: 10.1038/s41598-018-21342-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 02/02/2018] [Indexed: 02/07/2023] Open
Abstract
Most Group I Clostridium botulinum strains harbor botulinum neurotoxin (bont) genes on their chromosome, while some carry these genes (including bont/a, bont/b, and bont/f) on large plasmids. Prior work in our laboratory demonstrated that Group I BoNT plasmids were mobilized to C. botulinum recipient strains containing the Tn916 transposon. Here, we show that Tn916 is nonessential for plasmid transfer. Relying on an auxotrophic donor phenotype and a plasmid-borne selectable marker, we observed the transfer of pCLJ, a 270 kb plasmid harboring two bont genes, from its host strain to various clostridia. Transfer frequency was greatest to other Group I C. botulinum strains, but the plasmid was also transferred into traditionally nontoxigenic species, namely C. sporogenes and C. butyricum. Expression and toxicity of BoNT/A4 was confirmed in transconjugants by immunoblot and mouse bioassay. These data indicate that conjugation within the genus Clostridium can occur across physiological Groups of C. botulinum, supporting horizontal gene transfer via bont-bearing plasmids. The transfer of plasmids possessing bont genes to resistant Clostridium spp. such as C. sporogenes could impact biological safety for animals and humans. These plasmids may play an environmental role in initiating death in vertebrates, leading to decomposition and nutrient recycling of animal biomass.
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Affiliation(s)
- Erin M Nawrocki
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Marite Bradshaw
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Eric A Johnson
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
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Cohen JE, Wang R, Shen RF, Wu WW, Keller JE. Comparative pathogenomics of Clostridium tetani. PLoS One 2017; 12:e0182909. [PMID: 28800585 PMCID: PMC5553647 DOI: 10.1371/journal.pone.0182909] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 07/26/2017] [Indexed: 01/27/2023] Open
Abstract
Clostridium tetani and Clostridium botulinum produce two of the most potent neurotoxins known, tetanus neurotoxin and botulinum neurotoxin, respectively. Extensive biochemical and genetic investigation has been devoted to identifying and characterizing various C. botulinum strains. Less effort has been focused on studying C. tetani likely because recently sequenced strains of C. tetani show much less genetic diversity than C. botulinum strains and because widespread vaccination efforts have reduced the public health threat from tetanus. Our aim was to acquire genomic data on the U.S. vaccine strain of C. tetani to better understand its genetic relationship to previously published genomic data from European vaccine strains. We performed high throughput genomic sequence analysis on two wild-type and two vaccine C. tetani strains. Comparative genomic analysis was performed using these and previously published genomic data for seven other C. tetani strains. Our analysis focused on single nucleotide polymorphisms (SNP) and four distinct constituents of the mobile genome (mobilome): a hypervariable flagellar glycosylation island region, five conserved bacteriophage insertion regions, variations in three CRISPR (clustered regularly interspaced short palindromic repeats)-Cas (CRISPR-associated) systems, and a single plasmid. Intact type IA and IB CRISPR/Cas systems were within 10 of 11 strains. A type IIIA CRISPR/Cas system was present in two strains. Phage infection histories derived from CRISPR-Cas sequences indicate C. tetani encounters phages common among commensal gut bacteria and soil-borne organisms consistent with C. tetani distribution in nature. All vaccine strains form a clade distinct from currently sequenced wild type strains when considering variations in these mobile elements. SNP, flagellar glycosylation island, prophage content and CRISPR/Cas phylogenic histories provide tentative evidence suggesting vaccine and wild type strains share a common ancestor.
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Affiliation(s)
- Jonathan E. Cohen
- Laboratory of Respiratory and Special Pathogens, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Rong Wang
- Facility for Biotechnology Resources, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Rong-Fong Shen
- Facility for Biotechnology Resources, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - Wells W. Wu
- Facility for Biotechnology Resources, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
| | - James E. Keller
- Laboratory of Respiratory and Special Pathogens, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, United States of America
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15
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Peck MW, Smith TJ, Anniballi F, Austin JW, Bano L, Bradshaw M, Cuervo P, Cheng LW, Derman Y, Dorner BG, Fisher A, Hill KK, Kalb SR, Korkeala H, Lindström M, Lista F, Lúquez C, Mazuet C, Pirazzini M, Popoff MR, Rossetto O, Rummel A, Sesardic D, Singh BR, Stringer SC. Historical Perspectives and Guidelines for Botulinum Neurotoxin Subtype Nomenclature. Toxins (Basel) 2017; 9:toxins9010038. [PMID: 28106761 PMCID: PMC5308270 DOI: 10.3390/toxins9010038] [Citation(s) in RCA: 187] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 01/04/2017] [Accepted: 01/07/2017] [Indexed: 11/26/2022] Open
Abstract
Botulinum neurotoxins are diverse proteins. They are currently represented by at least seven serotypes and more than 40 subtypes. New clostridial strains that produce novel neurotoxin variants are being identified with increasing frequency, which presents challenges when organizing the nomenclature surrounding these neurotoxins. Worldwide, researchers are faced with the possibility that toxins having identical sequences may be given different designations or novel toxins having unique sequences may be given the same designations on publication. In order to minimize these problems, an ad hoc committee consisting of over 20 researchers in the field of botulinum neurotoxin research was convened to discuss the clarification of the issues involved in botulinum neurotoxin nomenclature. This publication presents a historical overview of the issues and provides guidelines for botulinum neurotoxin subtype nomenclature in the future.
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Affiliation(s)
| | - Theresa J Smith
- Molecular and Translational Sciences Division, United States Army Medical Institute of Infectious Diseases, Fort Detrick, MD 21702, USA.
| | - Fabrizio Anniballi
- National Reference Centre for Botulism, Istituto Superiore di Sanita, Rome 299-00161, Italy.
| | - John W Austin
- Bureau of Microbial Hazards, Health Canada, Ottawa, ON K1A 0K9, Canada.
| | - Luca Bano
- Istituto Zooprofilattico Sperimentale delle Venezie, Treviso 31020, Italy.
| | - Marite Bradshaw
- Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA.
| | - Paula Cuervo
- Área de Microbiología, Departamento de Patología, Universidad Nacional de Cuyo, Mendoza 450001, Argentina.
| | - Luisa W Cheng
- Foodborne Toxin Detection and Prevention Research Unit, Western Regional Research Center, U.S. Department of Agriculture, Albany, CA 94710, USA.
| | - Yagmur Derman
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki 00014, Finland.
| | | | - Audrey Fisher
- Applied Physics Laboratory, Johns Hopkins University, Baltimore, MD 21218, USA.
| | - Karen K Hill
- Los Alamos National Laboratories, Los Alamos, NM 87545, USA.
| | - Suzanne R Kalb
- National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA 30341, USA.
| | - Hannu Korkeala
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki 00014, Finland.
| | - Miia Lindström
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki 00014, Finland.
| | - Florigio Lista
- Army Medical and Veterinary Research Center, Rome 00184, Italy.
| | - Carolina Lúquez
- National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA.
| | - Christelle Mazuet
- Institut Pasteur, Bactéries anaérobies et Toxines, Paris 75015, France.
| | - Marco Pirazzini
- Biomedical Sciences Department, University of Padova, Padova 35131, Italy.
| | - Michel R Popoff
- Institut Pasteur, Bactéries anaérobies et Toxines, Paris 75015, France.
| | - Ornella Rossetto
- Biomedical Sciences Department, University of Padova, Padova 35131, Italy.
| | - Andreas Rummel
- Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover 30623, Germany.
| | - Dorothea Sesardic
- National Institute for Biological Standards and Control, a Centre of Medicines and Healthcare Products Regulatory Agency, Hertfordshire EN6 3QG, UK.
| | - Bal Ram Singh
- Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA.
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16
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Connan C, Popoff MR. Uptake of Clostridial Neurotoxins into Cells and Dissemination. Curr Top Microbiol Immunol 2017; 406:39-78. [PMID: 28879524 DOI: 10.1007/82_2017_50] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Clostridial neurotoxins, botulinum neurotoxins (BoNT) and tetanus neurotoxin (TeNT), are potent toxins, which are responsible for severe neurological diseases in man and animals. BoNTs induce a flaccid paralysis (botulism) by inhibiting acetylcholine release at the neuromuscular junctions, whereas TeNT causes a spastic paralysis (tetanus) by blocking the neurotransmitter release (glycine, GABA) in inhibitory interneurons within the central nervous system. Clostridial neurotoxins recognize specific receptor(s) on the target neuronal cells and enter via a receptor-mediated endocytosis. They transit through an acidic compartment which allows the translocation of the catalytic chain into the cytosol, a prerequisite step for the intracellular activity of the neurotoxins. TeNT migrates to the central nervous system by using a motor neuron as transport cell. TeNT enters a neutral pH compartment and undergoes a retrograde axonal transport to the spinal cord or brain, where the whole undissociated toxin is delivered and interacts with target neurons. Botulism most often results from ingestion of food contaminated with BoNT. Thus, BoNT passes through the intestinal epithelial barrier mainly via a transcytotic mechanism and then diffuses or is transported to the neuromuscular junctions by the lymph or blood circulation. Indeed, clostridial neurotoxins are specific neurotoxins which transit through a transport cell to gain access to the target neuron, and use distinct trafficking pathways in both cell types.
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Affiliation(s)
- Chloé Connan
- Unité Des Bactéries Anaérobies et Toxines, Institut Pasteur, 25 Rue Du Dr Roux, 75724, Paris Cedex 15, France
| | - Michel R Popoff
- Unité Des Bactéries Anaérobies et Toxines, Institut Pasteur, 25 Rue Du Dr Roux, 75724, Paris Cedex 15, France.
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17
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Entry of Botulinum Neurotoxin Subtypes A1 and A2 into Neurons. Infect Immun 2016; 85:IAI.00795-16. [PMID: 27795365 DOI: 10.1128/iai.00795-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 10/05/2016] [Indexed: 11/20/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) are the most toxic proteins for humans but also are common therapies for neurological diseases. BoNTs are dichain toxins, comprising an N-terminal catalytic domain (LC) disulfide bond linked to a C-terminal heavy chain (HC) which includes a translocation domain (HN) and a receptor binding domain (HC). Recently, the BoNT serotype A (BoNT/A) subtypes A1 and A2 were reported to possess similar potencies but different rates of cellular intoxication and pathology in a mouse model of botulism. The current study measured HCA1 and HCA2 entry into rat primary neurons and cultured Neuro2A cells. We found that there were two sequential steps during the association of BoNT/A with neurons. The initial step was ganglioside dependent, while the subsequent step involved association with synaptic vesicles. HCA1 and HCA2 entered the same population of synaptic vesicles and entered cells at similar rates. The primary difference was that HCA2 had a higher degree of receptor occupancy for cells and neurons than HcA1. Thus, HCA2 and HCA1 share receptors and entry pathway but differ in their affinity for receptor. The initial interaction of HCA1 and HCA2 with neurons may contribute to the unique pathologies of BoNT/A1 and BoNT/A2 in mouse models.
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18
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Ihekwaba AEC, Mura I, Walshaw J, Peck MW, Barker GC. An Integrative Approach to Computational Modelling of the Gene Regulatory Network Controlling Clostridium botulinum Type A1 Toxin Production. PLoS Comput Biol 2016; 12:e1005205. [PMID: 27855161 PMCID: PMC5113860 DOI: 10.1371/journal.pcbi.1005205] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 10/16/2016] [Indexed: 11/19/2022] Open
Abstract
Clostridium botulinum produces botulinum neurotoxins (BoNTs), highly potent substances responsible for botulism. Currently, mathematical models of C. botulinum growth and toxigenesis are largely aimed at risk assessment and do not include explicit genetic information beyond group level but integrate many component processes, such as signalling, membrane permeability and metabolic activity. In this paper we present a scheme for modelling neurotoxin production in C. botulinum Group I type A1, based on the integration of diverse information coming from experimental results available in the literature. Experiments show that production of BoNTs depends on the growth-phase and is under the control of positive and negative regulatory elements at the intracellular level. Toxins are released as large protein complexes and are associated with non-toxic components. Here, we systematically review and integrate those regulatory elements previously described in the literature for C. botulinum Group I type A1 into a population dynamics model, to build the very first computational model of toxin production at the molecular level. We conduct a validation of our model against several items of published experimental data for different wild type and mutant strains of C. botulinum Group I type A1. The result of this process underscores the potential of mathematical modelling at the cellular level, as a means of creating opportunities in developing new strategies that could be used to prevent botulism; and potentially contribute to improved methods for the production of toxin that is used for therapeutics. Clostridium botulinum produces botulinum neurotoxins (BoNTs), highly potent substances responsible for botulism. Currently, mathematical models of C. botulinum growth and toxigenesis are largely aimed at risk assessment and do not include explicit genetic information. In this paper we present modelling based on the integration of diverse information from experimental results available in the literature. Experiments show that production of BoNTs depends on the growth-phase and is under the control of positive and negative regulatory elements at the intracellular level. Here, we integrate these regulatory elements into a combined model of population dynamics and gene regulation to build the first computational model of toxin production at the molecular level. We conduct a validation of our model against several items of published experimental data for different wild type and mutant strains of C. botulinum Group I type A1. The result of this process underscores the potential of mathematical modelling at the cellular level, as a means of creating opportunities that could be used to prevent botulism, and potentially contribute to improved methods for the production of toxin used for therapeutics.
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Affiliation(s)
- Adaoha E. C. Ihekwaba
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich, United Kingdom
- * E-mail: (AECI); (IM)
| | - Ivan Mura
- Department of Industrial Engineering, Universidad de los Andes, Bogotá, Colombia
- * E-mail: (AECI); (IM)
| | - John Walshaw
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich, United Kingdom
- School of Computing Sciences, University of East Anglia, Norwich, United Kingdom
| | - Michael W. Peck
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich, United Kingdom
| | - Gary C. Barker
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich, United Kingdom
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19
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Brunt J, van Vliet AHM, van den Bos F, Carter AT, Peck MW. Diversity of the Germination Apparatus in Clostridium botulinum Groups I, II, III, and IV. Front Microbiol 2016; 7:1702. [PMID: 27840626 PMCID: PMC5083711 DOI: 10.3389/fmicb.2016.01702] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 10/12/2016] [Indexed: 01/17/2023] Open
Abstract
Clostridium botulinum is a highly dangerous pathogen that forms very resistant endospores that are ubiquitous in the environment, and which, under favorable conditions germinate to produce vegetative cells that multiply and form the exceptionally potent botulinum neurotoxin. To improve the control of botulinum neurotoxin-forming clostridia, it is important to understand the mechanisms involved in spore germination. Here we present models for spore germination in C. botulinum based on comparative genomics analyses, with C. botulinum Groups I and III sharing similar pathways, which differ from those proposed for C. botulinum Groups II and IV. All spores germinate in response to amino acids interacting with a germinant receptor, with four types of germinant receptor identified [encoded by various combinations of gerA, gerB, and gerC genes (gerX)]. There are three gene clusters with an ABC-like configuration; ABC [gerX1], ABABCB [gerX2] and ACxBBB [gerX4], and a single CA-B [gerX3] gene cluster. Subtypes have been identified for most germinant receptor types, and the individual GerX subunits of each cluster show similar grouping in phylogenetic trees. C. botulinum Group I contained the largest variety of gerX subtypes, with three gerX1, three gerX2, and one gerX3 subtypes, while C. botulinum Group III contained two gerX1 types and one gerX4. C. botulinum Groups II and IV contained a single germinant receptor, gerX3 and gerX1, respectively. It is likely that all four C. botulinum Groups include a SpoVA channel involved in dipicolinic acid release. The cortex-lytic enzymes present in C. botulinum Groups I and III appear to be CwlJ and SleB, while in C. botulinum Groups II and IV, SleC appears to be important.
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Affiliation(s)
- Jason Brunt
- Gut Health and Food Safety, Institute of Food ResearchNorwich, UK
| | - Arnoud H. M. van Vliet
- Gut Health and Food Safety, Institute of Food ResearchNorwich, UK
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of SurreyGuildford, UK
| | | | - Andrew T. Carter
- Gut Health and Food Safety, Institute of Food ResearchNorwich, UK
| | - Michael W. Peck
- Gut Health and Food Safety, Institute of Food ResearchNorwich, UK
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Neurotoxins from Clostridium botulinum (serotype A) isolated from the soil of Mendoza (Argentina) differ from the A-Hall archetype and from that causing infant botulism. Toxicon 2016; 121:30-35. [PMID: 27527271 DOI: 10.1016/j.toxicon.2016.08.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 08/10/2016] [Accepted: 08/11/2016] [Indexed: 11/22/2022]
Abstract
The type A of neurotoxin produced by Clostridium botulinum is the prevalent serotype in strains of Mendoza. The soil is the main reservoir for C.botulinum and is possibly one of the infection sources in infant botulism. In this study, we characterized and compared autochthonous C. botulinum strains and their neurotoxins. Bacterial samples were obtained from the soil and from fecal samples collected from children with infant botulism. We first observed differences in the appearance of the colonies between strains from each source and with the A Hall control strain. In addition, purified neurotoxins of both strains were found to be enriched in a band of 300 kDa, whereas the A-Hall strain was mainly made up of a band of ∼600 kDa. This finding is in line with the lack of hemagglutinating activity of the neurotoxins under study. Moreover, the proteolytic activity of C. botulinum neurotoxins was evaluated against SNARE (soluble N-ethylmaleimide-sensitive factor-attachment protein receptor) proteins from rat brain. It was observed that both, SNAP 25 (synaptosomal-associated protein 25) and VAMP 2 (vesicle-associated membrane protein) were cleaved by the neurotoxins isolated from the soil strains, whereas the neurotoxins from infant botulism strains only induced a partial cleavage of VAMP 2. On the other hand, the neurotoxin from the A-Hall strain was able to cleave both proteins, though at a lesser extent. Our data indicate that the C.botulinum strain isolated from the soil, and its BoNT, exhibit different properties compared to the strain obtained from infant botulism patients, and from the A-Hall archetype.
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Abstract
C. botulinum Groups I and II form botulinum neurotoxin and cause foodborne botulism. Increased knowledge of C. botulinum Group I and II genomes and neurotoxin diversity. Impact on food safety via improved surveillance and tracing/tracking during outbreaks. New insights into C. botulinum biology, food chain transmission, evolution.
The deadly botulinum neurotoxin formed by Clostridium botulinum is the causative agent of foodborne botulism. The increasing availability of C. botulinum genome sequences is starting to allow the genomic diversity of C. botulinum Groups I and II and their neurotoxins to be characterised. This information will impact on microbiological food safety through improved surveillance and tracing/tracking during outbreaks, and a better characterisation of C. botulinum Groups I and II, including the risk presented, and new insights into their biology, food chain transmission, and evolution.
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Draft Genome Sequence of
Clostridium sporogenes
Strain UC9000 Isolated from Raw Milk. GENOME ANNOUNCEMENTS 2016; 4:4/2/e00244-16. [PMID: 27081128 PMCID: PMC4832156 DOI: 10.1128/genomea.00244-16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Clostridium sporogenes is a causative agent of food spoilage and is often used as the nontoxigenic surrogate for Clostridium botulinum. Here, we described the draft genome sequence and annotation of C. sporogenes strain UC9000 isolated from raw milk.
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Carter AT, Austin JW, Weedmark KA, Peck MW. Evolution of Chromosomal Clostridium botulinum Type E Neurotoxin Gene Clusters: Evidence Provided by Their Rare Plasmid-Borne Counterparts. Genome Biol Evol 2016; 8:540-55. [PMID: 26936890 PMCID: PMC4824171 DOI: 10.1093/gbe/evw017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Analysis of more than 150 Clostridium botulinum Group II type E genomes identified a small fraction (6%) where neurotoxin-encoding genes were located on plasmids. Seven closely related (134–144 kb) neurotoxigenic plasmids of subtypes E1, E3, and E10 were characterized; all carried genes associated with plasmid mobility via conjugation. Each plasmid contained the same 24-kb neurotoxin cluster cassette (six neurotoxin cluster and six flanking genes) that had split a helicase gene, rather than the more common chromosomal rarA. The neurotoxin cluster cassettes had evolved as separate genetic units which had either exited their chromosomal rarA locus in a series of parallel events, inserting into the plasmid-borne helicase gene, or vice versa. A single intact version of the helicase gene was discovered on a nonneurotoxigenic form of this plasmid. The observed low frequency for the plasmid location may reflect one or more of the following: 1) Less efficient recombination mechanism for the helicase gene target, 2) lack of suitable target plasmids, and 3) loss of neurotoxigenic plasmids. Type E1 and E10 plasmids possessed a Clustered Regularly Interspaced Short Palindromic Repeats locus with spacers that recognized C. botulinum Group II plasmids, but not C. botulinum Group I plasmids, demonstrating their long-term separation. Clostridium botulinum Group II type E strains also carry nonneurotoxigenic plasmids closely related to C. botulinum Group II types B and F plasmids. Here, the absence of neurotoxin cassettes may be because recombination requires both a specific mechanism and specific target sequence, which are rarely found together.
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Affiliation(s)
- Andrew T Carter
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Norwich, United Kingdom
| | - John W Austin
- Bureau of Microbial Hazards, Health Products and Food Branch, Health Canada, Ottawa, ON, Canada
| | - Kelly A Weedmark
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB, Canada
| | - Michael W Peck
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Norwich, United Kingdom
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Mechanism of substrate recognition by the novel Botulinum Neurotoxin subtype F5. Sci Rep 2016; 6:19875. [PMID: 26794648 PMCID: PMC4726221 DOI: 10.1038/srep19875] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/21/2015] [Indexed: 11/17/2022] Open
Abstract
Botulinum Neurotoxins (BoNTs) are the causative agents of botulism, which act by potently inhibiting the neurotransmitter release in motor neurons. Seven serotypes of BoNTs designated as BoNT/A-G have been identified. Recently, two novel types of Botulinum neurotoxins, which cleave a novel scissile bond, L54-E55, of VAMP-2 have been reported including BoNT/F subtype F5 and serotype H. However, little has been known on how these BoNTs recognize their substrates. The present study addressed for the first time the unique substrate recognition mechanism of LC/F5. Our data indicated that the optimal peptide required for efficient LC/F5 substrate cleavage is VAMP-2 (20–65). Interestingly, the overall mode of substrate recognition adopted by LC/F5 was similar to LC/F1, except that its recognition sites were shifted one helix toward the N-terminus of VAMP-2 when compared to that of LC/F1. The composition of LC/F5 pockets were found to have changed accordingly to facilitate specific recognition of these new sites of VAMP-2, including the P2′, P1′, P2, P3, B3, B2 and B1 sites. The study provides direct evidence of the evolutionary adaption of BoNT to recognize its substrate which is useful for effective antitoxin and inhibitor development.
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Ihekwaba AEC, Mura I, Malakar PK, Walshaw J, Peck MW, Barker GC. New Elements To Consider When Modeling the Hazards Associated with Botulinum Neurotoxin in Food. J Bacteriol 2016; 198:204-11. [PMID: 26350137 PMCID: PMC4751798 DOI: 10.1128/jb.00630-15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) produced by the anaerobic bacterium Clostridium botulinum are the most potent biological substances known to mankind. BoNTs are the agents responsible for botulism, a rare condition affecting the neuromuscular junction and causing a spectrum of diseases ranging from mild cranial nerve palsies to acute respiratory failure and death. BoNTs are a potential biowarfare threat and a public health hazard, since outbreaks of foodborne botulism are caused by the ingestion of preformed BoNTs in food. Currently, mathematical models relating to the hazards associated with C. botulinum, which are largely empirical, make major contributions to botulinum risk assessment. Evaluated using statistical techniques, these models simulate the response of the bacterium to environmental conditions. Though empirical models have been successfully incorporated into risk assessments to support food safety decision making, this process includes significant uncertainties so that relevant decision making is frequently conservative and inflexible. Progression involves encoding into the models cellular processes at a molecular level, especially the details of the genetic and molecular machinery. This addition drives the connection between biological mechanisms and botulism risk assessment and hazard management strategies. This review brings together elements currently described in the literature that will be useful in building quantitative models of C. botulinum neurotoxin production. Subsequently, it outlines how the established form of modeling could be extended to include these new elements. Ultimately, this can offer further contributions to risk assessments to support food safety decision making.
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Affiliation(s)
- Adaoha E C Ihekwaba
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich, United Kingdom
| | - Ivan Mura
- Faculty of Engineering, EAN University, Bogotá, Colombia
| | - Pradeep K Malakar
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich, United Kingdom
| | - John Walshaw
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich, United Kingdom
| | - Michael W Peck
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich, United Kingdom
| | - G C Barker
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich, United Kingdom
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Schill KM, Wang Y, Butler RR, Pombert JF, Reddy NR, Skinner GE, Larkin JW. Genetic Diversity of Clostridium sporogenes PA 3679 Isolates Obtained from Different Sources as Resolved by Pulsed-Field Gel Electrophoresis and High-Throughput Sequencing. Appl Environ Microbiol 2016; 82:384-93. [PMID: 26519392 PMCID: PMC4702626 DOI: 10.1128/aem.02616-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 10/21/2015] [Indexed: 12/27/2022] Open
Abstract
Clostridium sporogenes PA 3679 is a nonpathogenic, nontoxic model organism for proteolytic Clostridium botulinum used in the validation of conventional thermal food processes due to its ability to produce highly heat-resistant endospores. Because of its public safety importance, the uncertain taxonomic classification and genetic diversity of PA 3679 are concerns. Therefore, isolates of C. sporogenes PA 3679 were obtained from various sources and characterized using pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing. The phylogenetic relatedness and genetic variability were assessed based on 16S rRNA gene sequencing and whole-genome single nucleotide polymorphism (SNP) analysis. All C. sporogenes PA 3679 isolates were categorized into two clades (clade I containing ATCC 7955 NCA3679 isolates 1961-2, 1990, and 2007 and clade II containing PA 3679 isolates NFL, UW, FDA, and Campbell and ATCC 7955 NCA3679 isolate 1961-4). The 16S maximum likelihood (ML) tree clustered both clades within proteolytic C. botulinum strains, with clade I forming a distinct cluster with other C. sporogenes non-PA 3679 strains. SNP analysis revealed that clade I isolates were more similar to the genomic reference PA 3679 (NCTC8594) genome (GenBank accession number AGAH00000000.1) than clade II isolates were. The genomic reference C. sporogenes PA 3679 (NCTC8594) genome and clade I C. sporogenes isolates were genetically distinct from those obtained from other sources (University of Wisconsin, National Food Laboratory, U.S. Food and Drug Administration, and Campbell's Soup Company). Thermal destruction studies revealed that clade I isolates were more sensitive to high temperature than clade II isolates were. Considering the widespread use of C. sporogenes PA 3679 and its genetic information in numerous studies, the accurate identification and genetic characterization of C. sporogenes PA 3679 are of critical importance.
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Affiliation(s)
- Kristin M Schill
- Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Bedford Park, Illinois, USA
| | - Yun Wang
- Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Bedford Park, Illinois, USA
| | - Robert R Butler
- Illinois Institute of Technology, Department of Biology, Chicago, Illinois, USA
| | | | - N Rukma Reddy
- Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Bedford Park, Illinois, USA
| | - Guy E Skinner
- Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Bedford Park, Illinois, USA
| | - John W Larkin
- Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Bedford Park, Illinois, USA
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Genomic characterization of Italian Clostridium botulinum group I strains. INFECTION GENETICS AND EVOLUTION 2015; 36:62-71. [DOI: 10.1016/j.meegid.2015.08.042] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 08/27/2015] [Accepted: 08/31/2015] [Indexed: 02/07/2023]
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Ihekwaba AEC, Mura I, Peck MW, Barker GC. The pattern of growth observed for Clostridium botulinum type A1 strain ATCC 19397 is influenced by nutritional status and quorum sensing: a modelling perspective. Pathog Dis 2015; 73:ftv084. [PMID: 26449712 PMCID: PMC4622173 DOI: 10.1093/femspd/ftv084] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 08/14/2015] [Accepted: 09/30/2015] [Indexed: 01/10/2023] Open
Abstract
Botulinum neurotoxins (BoNTs) produced by the anaerobic bacterium Clostridium botulinum are the most poisonous substances known to mankind. However, toxin regulation and signals triggering synthesis as well as the regulatory network and actors controlling toxin production are unknown. Experiments show that the neurotoxin gene is growth phase dependent for C. botulinum type A1 strain ATCC 19397, and toxin production is influenced both by culture conditions and nutritional status of the medium. Building mathematical models to describe the genetic and molecular machinery that drives the synthesis and release of BoNT requires a simultaneous description of the growth of the bacterium in culture. Here, we show four plausible modelling options which could be considered when constructing models describing the pattern of growth observed in a botulinum growth medium. Commonly used bacterial growth models are unsuitable to fit the pattern of growth observed, since they only include monotonic growth behaviour. We find that a model that includes both the nutritional status and the ability of the cells to sense their surroundings in a quorum-sensing manner is most successful at explaining the pattern of growth obtained for C. botulinum type A1 strain ATCC 19397.
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Affiliation(s)
- Adaoha E C Ihekwaba
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, UK
| | - Ivan Mura
- Faculty of Engineering, EAN University, Carrera 11 No. 78 - 47, Bogotá, Colombia
| | - Michael W Peck
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, UK
| | - G C Barker
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, UK
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Characterization of a Unique Tetrasaccharide and Distinct Glycoproteome in the O-Linked Protein Glycosylation System of Neisseria elongata subsp. glycolytica. J Bacteriol 2015; 198:256-67. [PMID: 26483525 DOI: 10.1128/jb.00620-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 10/14/2015] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED Broad-spectrum O-linked protein glycosylation is well characterized in the major Neisseria species of importance to human health and disease. Within strains of Neisseria gonorrhoeae, N. meningitidis, and N. lactamica, protein glycosylation (pgl) gene content and the corresponding oligosaccharide structure are fairly well conserved, although intra- and interstrain variability occurs. The status of such systems in distantly related commensal species, however, remains largely unexplored. Using a strain of deeply branching Neisseria elongata subsp. glycolytica, a heretofore unrecognized tetrasaccharide glycoform consisting of di-N-acetylbacillosamine-glucose-di-N-acetyl hexuronic acid-N-acetylhexosamine (diNAcBac-Glc-diNAcHexA-HexNAc) was identified. Directed mutagenesis, mass spectrometric analysis, and glycan serotyping confirmed that the oligosaccharide is an extended version of the diNAcBac-Glc-based structure seen in N. gonorrhoeae and N. meningitidis generated by the successive actions of PglB, PglC, and PglD and glucosyltransferase PglH orthologues. In addition, a null mutation in the orthologue of the broadly conserved but enigmatic pglG gene precluded expression of the extended glycoform, providing the first evidence that its product is a functional glycosyltransferase. Despite clear evidence for a substantial number of glycoprotein substrates, the major pilin subunit of the endogenous type IV pilus was not glycosylated. The latter finding raises obvious questions as to the relative distribution of pilin glycosylation within the genus, how protein glycosylation substrates are selected, and the overall structure-function relationships of broad-spectrum protein glycosylation. Together, the results of this study provide a foundation upon which to assess neisserial O-linked protein glycosylation diversity at the genus level. IMPORTANCE Broad-spectrum protein glycosylation systems are well characterized in the pathogenic Neisseria species N. gonorrhoeae and N. meningitidis. A number of lines of evidence indicate that the glycan components in these systems are subject to diversifying selection and suggest that glycan variation may be driven in the context of glycosylation of the abundant and surface-localized pilin protein PilE, the major subunit of type IV pili. Here, we examined protein glycosylation in a distantly related, nonpathogenic neisserial species, Neisseria elongata subsp. glycolytica. This system has clear similarities to the systems found in pathogenic species but makes novel glycoforms utilizing a glycosyltransferase that is widely conserved at the genus level but whose function until now remained unknown. Remarkably, PilE pilin is not glycosylated in this species, a finding that raises important questions about the evolutionary trajectories and overall structure-function relationships of broad-spectrum protein glycosylation systems in bacteria.
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Isolation of nanomolar scFvs of non-human primate origin, cross-neutralizing botulinum neurotoxins A1 and A2 by targeting their heavy chain. BMC Biotechnol 2015; 15:86. [PMID: 26382731 PMCID: PMC4574468 DOI: 10.1186/s12896-015-0206-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 09/11/2015] [Indexed: 12/14/2022] Open
Abstract
Background Botulism is a naturally occurring disease, mainly caused by the ingestion of food contaminated by the botulinum neurotoxins (BoNTs). Botulinum neurotoxins are the most lethal. They are classified among the six major biological warfare agents by the Centers for Disease Control. BoNTs act on the cholinergic motoneurons, where they cleave proteins implicated in acetylcholine vesicle exocytosis. This exocytosis inhibition induces a flaccid paralysis progressively affecting all the muscles and generally engendering a respiratory distress. BoNTs are also utilized in medicine, mainly for the treatment of neuromuscular disorders, preventing large scale vaccination. Botulism specific treatment requires injections of antitoxins, usually of equine origin and thus poorly tolerated. Therefore, development of human or human-like neutralizing antibodies is of a major interest, and it is the subject of the European framework project called “AntiBotABE”. Results In this study, starting from a macaque immunized with the recombinant heavy chain of BoNT/A1 (BoNT/A1-HC), an immune antibody phage-display library was generated and antibody fragments (single chain Fragment variable) with nanomolar affinity were isolated and further characterized. The neutralization capacities of these scFvs were analyzed in the mouse phrenic nerve-hemidiaphragm assay. Conclusions After a three-round panning, 24 antibody fragments with affinity better than 10 nM were isolated. Three of them neutralized BoNT/A1 efficiently and two cross-neutralized BoNT/A1 and BoNT/A2 subtypes in the mouse phrenic nerve-hemidiaphragm assay. These are the first monoclonal human-like antibodies cross-neutralizing both BoNT/A1 and BoNT/A2. The antibody A1HC38 was selected for further development, and could be clinically developed for the prophylaxis and treatment of botulism. Electronic supplementary material The online version of this article (doi:10.1186/s12896-015-0206-0) contains supplementary material, which is available to authorized users.
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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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Metabolic shift of Escherichia coli under salt stress in the presence of glycine betaine. Appl Environ Microbiol 2015; 80:4745-56. [PMID: 24858086 DOI: 10.1128/aem.00599-14] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An important area of food safety focuses on bacterial survival and growth in unfavorable environments. In order to understand how bacteria adapt to stresses other than nutrient limitation in batch cultures, we need to develop mechanistic models of intracellular regulation and metabolism under stress. We studied the growth of Escherichia coli in minimal medium with added salt and different osmoprotectants. To characterize the metabolic efficiency with a robust parameter, we identified the optical density (OD) values at the inflection points of measured "OD versus time" growth curves and described them as a function of glucose concentration. We found that the metabolic efficiency parameter did not necessarily follow the trend of decreasing specific growth rate as the salt concentration increased. In the absence of osmoprotectant, or in the presence of proline, the metabolic efficiency decreased with increasing NaCl concentration. However, in the presence of choline or glycine betaine, it increased between 2 and 4.5% NaCl before declining at 5% NaCl and above. Microarray analysis of the transcriptional network and proteomics analysis with glycine betaine in the medium indicated that between 4.5 and 5% NaCl, the metabolism switched from aerobic to fermentative pathways and that the response to osmotic stress is similar to that for oxidative stress. We conclude that, although the growth rate appeared to decrease smoothly with increasing NaCl, the metabolic strategy of cells changed abruptly at a threshold concentration of NaCl.
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Genomic Epidemiology of Clostridium botulinum Isolates from Temporally Related Cases of Infant Botulism in New South Wales, Australia. J Clin Microbiol 2015; 53:2846-53. [PMID: 26109442 DOI: 10.1128/jcm.00143-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 06/15/2015] [Indexed: 01/24/2023] Open
Abstract
Infant botulism is a potentially life-threatening paralytic disease that can be associated with prolonged morbidity if not rapidly diagnosed and treated. Four infants were diagnosed and treated for infant botulism in NSW, Australia, between May 2011 and August 2013. Despite the temporal relationship between the cases, there was no close geographical clustering or other epidemiological links. Clostridium botulinum isolates, three of which produced botulism neurotoxin serotype A (BoNT/A) and one BoNT serotype B (BoNT/B), were characterized using whole-genome sequencing (WGS). In silico multilocus sequence typing (MLST) found that two of the BoNT/A-producing isolates shared an identical novel sequence type, ST84. The other two isolates were single-locus variants of this sequence type (ST85 and ST86). All BoNT/A-producing isolates contained the same chromosomally integrated BoNT/A2 neurotoxin gene cluster. The BoNT/B-producing isolate carried a single plasmid-borne bont/B gene cluster, encoding BoNT subtype B6. Single nucleotide polymorphism (SNP)-based typing results corresponded well with MLST; however, the extra resolution provided by the whole-genome SNP comparisons showed that the isolates differed from each other by >3,500 SNPs. WGS analyses indicated that the four infant botulism cases were caused by genomically distinct strains of C. botulinum that were unlikely to have originated from a common environmental source. The isolates did, however, cluster together, compared with international isolates, suggesting that C. botulinum from environmental reservoirs throughout NSW have descended from a common ancestor. Analyses showed that the high resolution of WGS provided important phylogenetic information that would not be captured by standard seven-loci MLST.
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Implications of Genome-Based Discrimination between Clostridium botulinum Group I and Clostridium sporogenes Strains for Bacterial Taxonomy. Appl Environ Microbiol 2015; 81:5420-9. [PMID: 26048939 DOI: 10.1128/aem.01159-15] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 05/26/2015] [Indexed: 01/08/2023] Open
Abstract
Taxonomic classification of Clostridium botulinum is based on the production of botulinum neurotoxin (BoNT), while closely related, nontoxic organisms are classified as Clostridium sporogenes. However, this taxonomic organization does not accurately mirror phylogenetic relationships between these species. A phylogenetic reconstruction using 2,016 orthologous genes shared among strains of C. botulinum group I and C. sporogenes clearly separated these two species into discrete clades which showed ∼93% average nucleotide identity (ANI) between them. Clustering of strains based on the presence of variable orthologs revealed 143 C. sporogenes clade-specific genetic signatures, a subset of which were further evaluated for their ability to correctly classify a panel of presumptive C. sporogenes strains by PCR. Genome sequencing of several C. sporogenes strains lacking these signatures confirmed that they clustered with C. botulinum strains in a core genome phylogenetic tree. Our analysis also identified C. botulinum strains that contained C. sporogenes clade-specific signatures and phylogenetically clustered with C. sporogenes strains. The genome sequences of two bont/B2-containing strains belonging to the C. sporogenes clade contained regions with similarity to a bont-bearing plasmid (pCLD), while two different strains belonging to the C. botulinum clade carried bont/B2 on the chromosome. These results indicate that bont/B2 was likely acquired by C. sporogenes strains through horizontal gene transfer. The genome-based classification of these species used to identify candidate genes for the development of rapid assays for molecular identification may be applicable to additional bacterial species that are challenging with respect to their classification.
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Apertures in the Clostridium sporogenes spore coat and exosporium align to facilitate emergence of the vegetative cell. Food Microbiol 2015; 51:45-50. [PMID: 26187826 PMCID: PMC4521118 DOI: 10.1016/j.fm.2015.04.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 03/24/2015] [Accepted: 04/28/2015] [Indexed: 11/23/2022]
Abstract
Clostridium sporogenes forms highly heat resistant endospores, enabling this bacterium to survive adverse conditions. Subsequently, spores may germinate, giving rise to vegetative cells that multiply and lead to food spoilage. Electron microscopy was used to visualise changes in spore structures during germination, emergence and outgrowth. C. sporogenes spores were surrounded by an exosporium that was oval in shape and typically 3 μm in length. An aperture of 0.3–0.4 μm was observed at one end of the exosporium. The rupture of the spore coats occurs adjacent to the opening in the exosporium. The germinated cell emerges through this hole in the spore coat and then through the pre-existing aperture in the exosporium, before eventually being released, leaving behind a largely intact exosporium with an enlarged aperture (0.7–1.0 μm) and coat shell. The formation of this aperture, its function and its alignment with the spore coat is discussed. Electron microscopy was used to study structures of Clostridium sporogenes spores. Spore exosporia possessed either a terminal aperture or a lipped protrusion. Cells emerged through the preformed aperture or sporiduct of the spore. Apertures in the spore coat and exosporium were aligned, and may be predetermined.
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36
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Carter AT, Austin JW, Weedmark KA, Corbett C, Peck MW. Three classes of plasmid (47-63 kb) carry the type B neurotoxin gene cluster of group II Clostridium botulinum. Genome Biol Evol 2015; 6:2076-87. [PMID: 25079343 PMCID: PMC4231633 DOI: 10.1093/gbe/evu164] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Pulsed-field gel electrophoresis and DNA sequence analysis of 26 strains of Group II (nonproteolytic) Clostridium botulinum type B4 showed that 23 strains carried their neurotoxin gene cluster on a 47–63 kb plasmid (three strains lacked any hybridization signal for the neurotoxin gene, presumably having lost their plasmid). Unexpectedly, no neurotoxin genes were found on the chromosome. This apparent constraint on neurotoxin gene transfer to the chromosome stands in marked contrast to Group I C. botulinum, in which neurotoxin gene clusters are routinely found in both locations. The three main classes of type B4 plasmid identified in this study shared different regions of homology, but were unrelated to any Group I or Group III plasmid. An important evolutionary aspect firmly links plasmid class to geographical origin, with one class apparently dominant in marine environments, whereas a second class is dominant in European terrestrial environments. A third class of plasmid is a hybrid between the other two other classes, providing evidence for contact between these seemingly geographically separated populations. Mobility via conjugation has been previously demonstrated for the type B4 plasmid of strain Eklund 17B, and similar genes associated with conjugation are present in all type B4 plasmids now described. A plasmid toxin–antitoxin system pemI gene located close to the neurotoxin gene cluster and conserved in each type B4 plasmid class may be important in understanding the mechanism which regulates this unique and unexpected bias toward plasmid-borne neurotoxin genes in Group II C. botulinum type B4.
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Affiliation(s)
- Andrew T Carter
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Norwich, United Kingdom
| | - John W Austin
- Bureau of Microbial Hazards, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada
| | - Kelly A Weedmark
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Cindi Corbett
- National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada
| | - Michael W Peck
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Norwich, United Kingdom
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Kull S, Schulz KM, Strotmeier JWN, Kirchner S, Schreiber T, Bollenbach A, Dabrowski PW, Nitsche A, Kalb SR, Dorner MB, Barr JR, Rummel A, Dorner BG. Isolation and functional characterization of the novel Clostridium botulinum neurotoxin A8 subtype. PLoS One 2015; 10:e0116381. [PMID: 25658638 PMCID: PMC4320087 DOI: 10.1371/journal.pone.0116381] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 12/06/2014] [Indexed: 12/31/2022] Open
Abstract
Botulism is a severe neurological disease caused by the complex family of botulinum neurotoxins (BoNT). Based on the different serotypes known today, a classification of serotype variants termed subtypes has been proposed according to sequence diversity and immunological properties. However, the relevance of BoNT subtypes is currently not well understood. Here we describe the isolation of a novel Clostridium botulinum strain from a food-borne botulism outbreak near Chemnitz, Germany. Comparison of its botulinum neurotoxin gene sequence with published sequences identified it to be a novel subtype within the BoNT/A serotype designated BoNT/A8. The neurotoxin gene is located within an ha-orfX+ cluster and showed highest homology to BoNT/A1, A2, A5, and A6. Unexpectedly, we found an arginine insertion located in the HC domain of the heavy chain, which is unique compared to all other BoNT/A subtypes known so far. Functional characterization revealed that the binding characteristics to its main neuronal protein receptor SV2C seemed unaffected, whereas binding to membrane-incorporated gangliosides was reduced in comparison to BoNT/A1. Moreover, we found significantly lower enzymatic activity of the natural, full-length neurotoxin and the recombinant light chain of BoNT/A8 compared to BoNT/A1 in different endopeptidase assays. Both reduced ganglioside binding and enzymatic activity may contribute to the considerably lower biological activity of BoNT/A8 as measured in a mouse phrenic nerve hemidiaphragm assay. Despite its reduced activity the novel BoNT/A8 subtype caused severe botulism in a 63-year-old male. To our knowledge, this is the first description and a comprehensive characterization of a novel BoNT/A subtype which combines genetic information on the neurotoxin gene cluster with an in-depth functional analysis using different technical approaches. Our results show that subtyping of BoNT is highly relevant and that understanding of the detailed toxin function might pave the way for the development of novel therapeutics and tailor-made antitoxins.
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Affiliation(s)
- Skadi Kull
- Biological Toxins (ZBS3), Centre for Biological Threats and Special Pathogens, Robert Koch-Institut, Berlin, Germany
| | - K. Melanie Schulz
- Biological Toxins (ZBS3), Centre for Biological Threats and Special Pathogens, Robert Koch-Institut, Berlin, Germany
| | | | - Sebastian Kirchner
- Biological Toxins (ZBS3), Centre for Biological Threats and Special Pathogens, Robert Koch-Institut, Berlin, Germany
| | - Tanja Schreiber
- Biological Toxins (ZBS3), Centre for Biological Threats and Special Pathogens, Robert Koch-Institut, Berlin, Germany
| | | | - P. Wojtek Dabrowski
- Highly Pathogenic Viruses (ZBS1), Centre for Biological Threats and Special Pathogens, Robert Koch-Institut, Berlin, Germany
| | - Andreas Nitsche
- Highly Pathogenic Viruses (ZBS1), Centre for Biological Threats and Special Pathogens, Robert Koch-Institut, Berlin, Germany
| | - Suzanne R. Kalb
- Centers for Disease Control and Prevention, National Center for Environmental Health, Division of Laboratory Sciences, Atlanta, Georgia, United States of America
| | - Martin B. Dorner
- Biological Toxins (ZBS3), Centre for Biological Threats and Special Pathogens, Robert Koch-Institut, Berlin, Germany
| | - John R. Barr
- Centers for Disease Control and Prevention, National Center for Environmental Health, Division of Laboratory Sciences, Atlanta, Georgia, United States of America
| | - Andreas Rummel
- Institut für Toxikologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Brigitte G. Dorner
- Biological Toxins (ZBS3), Centre for Biological Threats and Special Pathogens, Robert Koch-Institut, Berlin, Germany
- * E-mail:
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38
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An atypical outbreak of food-borne botulism due to Clostridium botulinum types B and E from ham. J Clin Microbiol 2014; 53:722-6. [PMID: 25428161 DOI: 10.1128/jcm.02942-14] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An outbreak of human botulism was due to consumption of ham containing botulinum neurotoxins B and E. A Clostridium botulinum type E strain isolated from ham was assigned to a new subtype (E12) based on bont/E gene sequencing and belongs to a new multilocus sequence subtype, as analyzed by whole-genome sequencing.
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39
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Carter AT, Peck MW. Genomes, neurotoxins and biology of Clostridium botulinum Group I and Group II. Res Microbiol 2014; 166:303-17. [PMID: 25445012 PMCID: PMC4430135 DOI: 10.1016/j.resmic.2014.10.010] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 10/10/2014] [Accepted: 10/21/2014] [Indexed: 11/29/2022]
Abstract
Recent developments in whole genome sequencing have made a substantial contribution to understanding the genomes, neurotoxins and biology of Clostridium botulinum Group I (proteolytic C. botulinum) and C. botulinum Group II (non-proteolytic C. botulinum). Two different approaches are used to study genomics in these bacteria; comparative whole genome microarrays and direct comparison of complete genome DNA sequences. The properties of the different types of neurotoxin formed, and different neurotoxin gene clusters found in C. botulinum Groups I and II are explored. Specific examples of botulinum neurotoxin genes are chosen for an in-depth discussion of neurotoxin gene evolution. The most recent cases of foodborne botulism are summarised.
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Affiliation(s)
- Andrew T Carter
- Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4 7UA, UK
| | - Michael W Peck
- Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4 7UA, UK
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Immunoprecipitation of native botulinum neurotoxin complexes from Clostridium botulinum subtype A strains. Appl Environ Microbiol 2014; 81:481-91. [PMID: 25362065 DOI: 10.1128/aem.02817-14] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) naturally exist as components of protein complexes containing nontoxic proteins. The nontoxic proteins impart stability of BoNTs in the gastrointestinal tract and during purification and handling. The two primary neurotoxin complexes (TCs) are (i) TC1, consisting of BoNT, nontoxin-nonhemagglutinin (NTNH), and hemagglutinins (HAs), and (ii) TC2, consisting of BoNT and NTNH (and possibly OrfX proteins). In this study, BoNT/A subtypes A1, A2, A3, and A5 were examined for the compositions of their TCs in culture extracts using immunoprecipitation (IP). IP analyses showed that BoNT/A1 and BoNT/A5 form TC1s, while BoNT/A2 and BoNT/A3 form TC2s. A Clostridium botulinum host strain expressing recombinant BoNT/A4 (normally present as a TC2) from an extrachromosomal plasmid formed a TC1 with complexing proteins from the host strain, indicating that the HAs and NTNH encoded on the chromosome associated with the plasmid-encoded BoNT/A4. Strain NCTC 2916 (A1/silent B1), which carries both an ha silent bont/b cluster and an orfX bont/a1 cluster, was also examined. IP analysis revealed that NCTC 2916 formed only a TC2 containing BoNT/A1 and its associated NTNH. No association between BoNT/A1 and the nontoxic proteins from the silent bont/b cluster was detected, although the HAs were expressed as determined by Western blotting analysis. Additionally, NTNH and HAs from the silent bont/b cluster did not form a complex in NCTC 2916. The stabilities of the two types of TC differed at various pHs and with addition of KCl and NaCl. TC1 complexes were more stable than TC2 complexes. Mouse serum stabilized TC2, while TC1 was unaffected.
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Smith TJ, Hill KK, Raphael BH. Historical and current perspectives on Clostridium botulinum diversity. Res Microbiol 2014; 166:290-302. [PMID: 25312020 DOI: 10.1016/j.resmic.2014.09.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2014] [Revised: 09/24/2014] [Accepted: 09/24/2014] [Indexed: 11/19/2022]
Abstract
For nearly one hundred years, researchers have attempted to categorize botulinum neurotoxin-producing clostridia and the toxins that they produce according to biochemical characterizations, serological comparisons, and genetic analyses. Throughout this period the bacteria and their toxins have defied such attempts at categorization. Below is a description of both historic and current Clostridium botulinum strain and neurotoxin information that illustrates how each new finding has significantly added to the knowledge of the botulinum neurotoxin-containing clostridia and their diversity.
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Affiliation(s)
- Theresa J Smith
- Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, MD 21702, USA.
| | - Karen K Hill
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Brian H Raphael
- Enteric Diseases Laboratory Branch, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
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Dahlsten E, Lindström M, Korkeala H. Mechanisms of food processing and storage-related stress tolerance in Clostridium botulinum. Res Microbiol 2014; 166:344-52. [PMID: 25303833 DOI: 10.1016/j.resmic.2014.09.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 09/26/2014] [Accepted: 09/26/2014] [Indexed: 12/28/2022]
Abstract
Vegetative cultures of Clostridium botulinum produce the extremely potent botulinum neurotoxin, and may jeopardize the safety of foods unless sufficient measures to prevent growth are applied. Minimal food processing relies on combinations of mild treatments, primarily to avoid deterioration of the sensory qualities of the food. Tolerance of C. botulinum to minimal food processing is well characterized. However, data on effects of successive treatments on robustness towards further processing is lacking. Developments in genetic manipulation tools and the availability of annotated genomes have allowed identification of genetic mechanisms involved in stress tolerance of C. botulinum. Most studies focused on low temperature, and the importance of various regulatory mechanisms in cold tolerance of C. botulinum has been demonstrated. Furthermore, novel roles in cold tolerance were shown for metabolic pathways under the control of these regulators. A role for secondary oxidative stress in tolerance to extreme temperatures has been proposed. Additionally, genetic mechanisms related to tolerance to heat, low pH, and high salinity have been characterized. Data on genetic stress-related mechanisms of psychrotrophic Group II C. botulinum strains are scarce; these mechanisms are of interest for food safety research and should thus be investigated. This minireview encompasses the importance of C. botulinum as a food safety hazard and its central physiological characteristics related to food-processing and storage-related stress. Special attention is given to recent findings considering genetic mechanisms C. botulinum utilizes in detecting and countering these adverse conditions.
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Affiliation(s)
- Elias Dahlsten
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, P. O. Box 66, FI-00014 Helsinki, Finland.
| | - Miia Lindström
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, P. O. Box 66, FI-00014 Helsinki, Finland.
| | - Hannu Korkeala
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, P. O. Box 66, FI-00014 Helsinki, Finland.
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Børud B, Anonsen JH, Viburiene R, Cohen EH, Samuelsen ABC, Koomey M. Extended glycan diversity in a bacterial protein glycosylation system linked to allelic polymorphisms and minimal genetic alterations in a glycosyltransferase gene. Mol Microbiol 2014; 94:688-99. [PMID: 25213144 DOI: 10.1111/mmi.12789] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2014] [Indexed: 12/17/2022]
Abstract
Glycans manifest in conjunction with the broad spectrum O-linked protein glycosylation in species within the genus Neisseria display intra- and interstrain diversity. Variability in glycan structure and antigenicity are attributable to differences in the content and expression status of glycan synthesis genes. Given the high degree of standing allelic polymorphisms in these genes, the level of glycan diversity may exceed that currently defined. Here, we identify unique protein-associated disaccharide glycoforms that carry N-acetylglucosamine (GlcNAc) at their non-reducing end. This altered structure was correlated with allelic variants of pglH whose product was previously demonstrated to be responsible for the expression of glucose (Glc)-containing disaccharides. Allele comparisons and site-specific mutagenesis showed that the presence of a single residue, alanine at position 303 in place of a glutamine, was sufficient for GlcNAc versus Glc incorporation. Phylogenetic analyses revealed that GlcNAc-containing disaccharides may be widely distributed within the pgl systems of Neisseria particularly in strains of N. meningitidis. Although analogous minimal structural alterations in glycosyltransferases have been documented in association with lipopolysaccharide and capsular polysaccharide variability, this appears to be the first example in which such changes have been implicated in glycan diversification within a bacterial protein glycosylation system.
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Affiliation(s)
- Bente Børud
- Department of Biosciences, University of Oslo, Oslo, Norway
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Brunt J, Plowman J, Gaskin DJH, Itchner M, Carter AT, Peck MW. Functional characterisation of germinant receptors in Clostridium botulinum and Clostridium sporogenes presents novel insights into spore germination systems. PLoS Pathog 2014; 10:e1004382. [PMID: 25210747 PMCID: PMC4161481 DOI: 10.1371/journal.ppat.1004382] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 08/04/2014] [Indexed: 01/05/2023] Open
Abstract
Clostridium botulinum is a dangerous pathogen that forms the highly potent botulinum toxin, which when ingested causes a deadly neuroparalytic disease. The closely related Clostridium sporogenes is occasionally pathogenic, frequently associated with food spoilage and regarded as the non-toxigenic equivalent of Group I C. botulinum. Both species form highly resistant spores that are ubiquitous in the environment and which, under favourable growth conditions germinate to produce vegetative cells. To improve the control of botulinum neurotoxin-forming clostridia, it is imperative to comprehend the mechanisms by which spores germinate. Germination is initiated following the recognition of small molecules (germinants) by a specific germinant receptor (GR) located in the spore inner membrane. The present study precisely defines clostridial GRs, germinants and co-germinants. Group I C. botulinum ATCC3502 contains two tricistronic and one pentacistronic GR operons, while C. sporogenes ATCC15579 has three tricistronic and one tetracistronic GR operons. Insertional knockout mutants, allied with characterisation of recombinant GRs shows for the first time that amino acid stimulated germination in C. botulinum requires two tri-cistronic encoded GRs which act in synergy and cannot function individually. Spore germination in C. sporogenes requires one tri-cistronic GR. Two other GRs form part of a complex involved in controlling the rate of amino-acid stimulated germination. The suitability of using C. sporogenes as a substitute for C. botulinum in germination studies and food challenge tests is discussed. Clostridium botulinum is a dangerous pathogen that forms the deadly botulinum neurotoxin. Strains of C. botulinum are present in the environment as spores. Under suitable conditions, the dormancy of the bacterial spore is broken, and germination occurs. Germination is initiated following the recognition of small molecules by a specific germinant receptor (GR) located within spores. Currently, the identification and characterisation of these GRs remains unknown, but is critical if strategies are to be developed to either prevent spore germination altogether, or to germinate all the spores and then inactivate the emergent sensitive vegetative cells. The present study has characterised two functionally active GRs in C. botulinum which act in synergy and cannot function individually, and a related functionally active GR in C. sporogenes. These GRs respond to amino acids. Other GRs appear to form part of a complex involved in controlling the speed of germination, or are not functionally active. This study provides new insights into the mechanisms involved in germination and will allow us to develop new strategies to control this deadly pathogen.
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Affiliation(s)
- Jason Brunt
- Gut Health and Food Safety, Institute of Food Research (IFR), Norwich Research Park, Colney, Norwich, Norfolk, United Kingdom
- * E-mail:
| | - June Plowman
- Gut Health and Food Safety, Institute of Food Research (IFR), Norwich Research Park, Colney, Norwich, Norfolk, United Kingdom
| | - Duncan J. H. Gaskin
- Gut Health and Food Safety, Institute of Food Research (IFR), Norwich Research Park, Colney, Norwich, Norfolk, United Kingdom
| | - Manoa Itchner
- Gut Health and Food Safety, Institute of Food Research (IFR), Norwich Research Park, Colney, Norwich, Norfolk, United Kingdom
| | - Andrew T. Carter
- Gut Health and Food Safety, Institute of Food Research (IFR), Norwich Research Park, Colney, Norwich, Norfolk, United Kingdom
| | - Michael W. Peck
- Gut Health and Food Safety, Institute of Food Research (IFR), Norwich Research Park, Colney, Norwich, Norfolk, United Kingdom
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Two novel toxin variants revealed by whole-genome sequencing of 175 Clostridium botulinum type E strains. Appl Environ Microbiol 2014; 80:6334-45. [PMID: 25107978 DOI: 10.1128/aem.01573-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We sequenced 175 Clostridium botulinum type E strains isolated from food, clinical, and environmental sources from northern Canada and analyzed their botulinum neurotoxin (bont) coding sequences (CDSs). In addition to bont/E1 and bont/E3 variant types, neurotoxin sequence analysis identified two novel BoNT type E variants termed E10 and E11. Strains producing type E10 were found along the eastern coastlines of Hudson Bay and the shores of Ungava Bay, while strains producing type E11 were only found in the Koksoak River region of Nunavik. Strains producing BoNT/E3 were widespread throughout northern Canada, with the exception of the coast of eastern Hudson Bay.
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Raphael BH, Shirey TB, Lúquez C, Maslanka SE. Distinguishing highly-related outbreak-associated Clostridium botulinum type A(B) strains. BMC Microbiol 2014; 14:192. [PMID: 25031122 PMCID: PMC4112988 DOI: 10.1186/1471-2180-14-192] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 07/10/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In the United States, most Clostridium botulinum type A strains isolated during laboratory investigations of human botulism demonstrate the presence of an expressed type A botulinum neurotoxin (BoNT/A) gene and an unexpressed BoNT/B gene. These strains are designated type A(B). The most common pulsed-field gel electrophoresis (PFGE) pattern in the C. botulinum PulseNet database is composed of A(B) strains. The purpose of this study was to evaluate the ability of genome sequencing and multi-loci variable number of tandem repeat analysis (MLVA) to differentiate such strains. RESULTS The genome sequences of type A(B) strains evaluated in this study are closely related and cluster together compared to other available C. botulinum Group I genomes. In silico multilocus sequence typing (MLST) analysis (7-loci) was unable to differentiate any of the type A(B) strains isolated from seven different outbreak investigations evaluated in this study. A 15-locus MLVA scheme demonstrated an improved ability to differentiate these strains, however, repeat unit variation among the strains was restricted to only two loci. Reference-free single nucleotide polymorphism (SNP) analysis demonstrated the ability to differentiate strains from all of the outbreaks examined and a non-outbreak associated strain. CONCLUSIONS This study confirms that type A(B) strains that share the same PFGE pattern also share closely-related genome sequences. The lack of a complete type A(B) strain representative genome sequence hinders the ability to assemble genomes by reference mapping and analysis of SNPs at pre-identified sites. However, compared to other methods evaluated in this study, a reference-free SNP analysis demonstrated optimal subtyping utility for type A(B) strains using de novo assembled genome sequences.
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Affiliation(s)
- Brian H Raphael
- Enteric Diseases Laboratory Branch, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Timothy B Shirey
- Enteric Diseases Laboratory Branch, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Carolina Lúquez
- Enteric Diseases Laboratory Branch, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Susan E Maslanka
- Enteric Diseases Laboratory Branch, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
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Wangroongsarb P, Kohda T, Jittaprasartsin C, Suthivarakom K, Kamthalang T, Umeda K, Sawanpanyalert P, Kozaki S, Ikuta K. Molecular characterization of Clostridium botulinum isolates from foodborne outbreaks in Thailand, 2010. PLoS One 2014; 9:e77792. [PMID: 24475015 PMCID: PMC3903786 DOI: 10.1371/journal.pone.0077792] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 09/04/2013] [Indexed: 12/18/2022] Open
Abstract
Background Thailand has had several foodborne outbreaks of botulism, one of the biggest being in 2006 when laboratory investigations identified the etiologic agent as Clostridium botulinum type A. Identification of the etiologic agent from outbreak samples is laborious using conventional microbiological methods and the neurotoxin mouse bioassay. Advances in molecular techniques have added enormous information regarding the etiology of outbreaks and characterization of isolates. We applied these methods in three outbreaks of botulism in Thailand in 2010. Methodology/Principal Findings A total of 19 cases were involved (seven each in Lampang and Saraburi and five in Maehongson provinces). The first outbreak in Lampang province in April 2010 was associated with C. botulinum type F, which was detected by conventional methods. Outbreaks in Saraburi and Maehongson provinces occurred in May and December were due to C. botulinum type A1(B) and B that were identified by conventional methods and molecular techniques, respectively. The result of phylogenetic sequence analysis showed that C. botulinum type A1(B) strain Saraburi 2010 was close to strain Iwate 2007. Molecular analysis of the third outbreak in Maehongson province showed C. botulinum type B8, which was different from B1–B7 subtype. The nontoxic component genes of strain Maehongson 2010 revealed that ha33, ha17 and botR genes were close to strain Okra (B1) while ha70 and ntnh genes were close to strain 111 (B2). Conclusion/Significance This study demonstrates the utility of molecular genotyping of C. botulinum and how it contributes to our understanding the epidemiology and variation of boNT gene. Thus, the recent botulism outbreaks in Thailand were induced by various C. botulinum types.
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Affiliation(s)
- Piyada Wangroongsarb
- Department of Medical Sciences, National Institute of Health, Nonthaburi, Thailand
| | - Tomoko Kohda
- Department of Veterinary Science, Osaka Prefecture University, Osaka, Japan
| | | | - Karun Suthivarakom
- Department of Medical Sciences, National Institute of Health, Nonthaburi, Thailand
| | - Thanitchi Kamthalang
- Department of Medical Sciences, National Institute of Health, Nonthaburi, Thailand
| | - Kaoru Umeda
- Department of Microbiology, Osaka City Institute of Public Health and Environmental Sciences, Osaka, Japan
| | | | - Shunji Kozaki
- Department of Veterinary Science, Osaka Prefecture University, Osaka, Japan
| | - Kazuyoshi Ikuta
- Department of Virology, Osaka University, Osaka, Japan
- * E-mail:
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Whole-genome single-nucleotide-polymorphism analysis for discrimination of Clostridium botulinum group I strains. Appl Environ Microbiol 2014; 80:2125-32. [PMID: 24463972 DOI: 10.1128/aem.03934-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clostridium botulinum is a genetically diverse Gram-positive bacterium producing extremely potent neurotoxins (botulinum neurotoxins A through G [BoNT/A-G]). The complete genome sequences of three strains harboring only the BoNT/A1 nucleotide sequence are publicly available. Although these strains contain a toxin cluster (HA(+) OrfX(-)) associated with hemagglutinin genes, little is known about the genomes of subtype A1 strains (termed HA(-) OrfX(+)) that lack hemagglutinin genes in the toxin gene cluster. We sequenced the genomes of three BoNT/A1-producing C. botulinum strains: two strains with the HA(+) OrfX(-) cluster (69A and 32A) and one strain with the HA(-) OrfX(+) cluster (CDC297). Whole-genome phylogenic single-nucleotide-polymorphism (SNP) analysis of these strains along with other publicly available C. botulinum group I strains revealed five distinct lineages. Strains 69A and 32A clustered with the C. botulinum type A1 Hall group, and strain CDC297 clustered with the C. botulinum type Ba4 strain 657. This study reports the use of whole-genome SNP sequence analysis for discrimination of C. botulinum group I strains and demonstrates the utility of this analysis in quickly differentiating C. botulinum strains harboring identical toxin gene subtypes. This analysis further supports previous work showing that strains CDC297 and 657 likely evolved from a common ancestor and independently acquired separate BoNT/A1 toxin gene clusters at distinct genomic locations.
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Morrison MJ, Imperiali B. The renaissance of bacillosamine and its derivatives: pathway characterization and implications in pathogenicity. Biochemistry 2014; 53:624-38. [PMID: 24383882 PMCID: PMC3951908 DOI: 10.1021/bi401546r] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
![]()
Prokaryote-specific
sugars, including N,N′-diacetylbacillosamine
(diNAcBac) and pseudaminic
acid, have experienced a renaissance in the past decade because of
their discovery in glycans related to microbial pathogenicity. DiNAcBac
is found at the reducing end of oligosaccharides of N- and O-linked
bacterial protein glycosylation pathways of Gram-negative pathogens,
including Campylobacter jejuni and Neisseria
gonorrhoeae. Further derivatization of diNAcBac results in
the nonulosonic acid known as legionaminic acid, which was first characterized
in the O-antigen of the lipopolysaccharide (LPS) in Legionella
pneumophila. Pseudaminic acid, an isomer of legionaminic
acid, is also important in pathogenic bacteria such as Helicobacter
pylori because of its occurrence in O-linked glycosylation
of flagellin proteins, which plays an important role in flagellar
assembly and motility. Here, we present recent advances in the characterization
of the biosynthetic pathways leading to these highly modified sugars
and investigation of the roles that each plays in bacterial fitness
and pathogenicity.
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Affiliation(s)
- Michael J Morrison
- Departments of Chemistry and Biology, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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Comparison of assembled Clostridium botulinum A1 genomes revealed their evolutionary relationship. Genomics 2013; 103:94-106. [PMID: 24369123 DOI: 10.1016/j.ygeno.2013.12.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 11/08/2013] [Accepted: 12/14/2013] [Indexed: 11/24/2022]
Abstract
Clostridium botulinum encompasses bacteria that produce at least one of the seven serotypes of botulinum neurotoxin (BoNT/A-G). The availability of genome sequences of four closely related Type A1 or A1(B) strains, as well as the A1-specific microarray, allowed the analysis of their genomic organizations and evolutionary relationship. The four genomes share >90% core genes and >96% functional groups. Phylogenetic analysis based on COG shows closer relations of the A1(B) strain, NCTC 2916, to B1 and F1 than A1 strains. Alignment of the genomes of the three A1 strains revealed a highly similar chromosomal structure with three small gaps in the genome of ATCC 19397 and one additional gap in the genome of Hall A, suggesting ATCC 19379 as an evolutionary intermediate between Hall A and ATCC 3502. Analyses of the four gap regions indicated potential horizontal gene transfer and recombination events important for the evolution of A1 strains.
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