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Majou D. Endopeptidase activities of Clostridium botulinum toxins in the development of this bacterium. Res Microbiol 2024:104216. [PMID: 38897423 DOI: 10.1016/j.resmic.2024.104216] [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: 02/14/2024] [Revised: 05/30/2024] [Accepted: 05/31/2024] [Indexed: 06/21/2024]
Abstract
By-products like CO₂ and organic acids, produced during Clostridium botulinum growth, appear to inhibit its development and reduce ATP production. A decrease in ATP production creates an imbalance in the ATP/GTP ratio. GTP activates CodY, which regulates BoNT expression. This toxin is released into the extracellular medium. Its light chains act as a specific endopeptidase, targeting SNARE proteins. The specific amino acids released enter the cells and are metabolized by the Stickland reaction, resulting in the synthesis of ATP. This ATP might then be used by histidine kinases to activate Spo0A, the main regulator initiating sporulation, through phosphorylation.
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Affiliation(s)
- Didier Majou
- ACTIA, 149, Rue de Bercy, 75595 Paris Cedex 12, France.
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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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Bowe BK, Wentz TG, Gregg BM, Tepp WH, Schill KM, Sharma S, Pellett S. Genomic Diversity, Competition, and Toxin Production by Group I and II Clostridium botulinum Strains Used in Food Challenge Studies. Microorganisms 2022; 10:1895. [PMID: 36296172 PMCID: PMC9611418 DOI: 10.3390/microorganisms10101895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 09/16/2022] [Accepted: 09/17/2022] [Indexed: 11/16/2022] Open
Abstract
Botulinum neurotoxins (BoNTs) produced by the bacteria Clostridium botulinum are the causative agent of human and animal botulism, a rare but serious and potentially deadly intoxication. Foodborne botulism is caused by the consumption of foods containing BoNTs, which results from contamination of foods with C. botulinum spores and toxin production by the bacteria during growth within the food. Validation of the safety of food products is essential in preventing foodborne botulism, however, limited guidance and standards exist for the selection of strains used in C. botulinum food challenge studies. Sequencing and genomics studies have revealed that C. botulinum is a large, diverse, and polyphyletic species, with physiologic and growth characteristics studied only in a few representatives. Little is known about potential growth competition or effects on toxin production between C. botulinum strains. In this study, we investigated an applied cocktail of ten C. botulinum strains, seven Group I and three Group II. Whole genome SNP alignments revealed that this strain cocktail encompasses the major clades of the Group I and II C. botulinum species. While growth competition appears to exist between several of the strains, the cocktail as a whole resulted in high levels of BoNT production.
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Affiliation(s)
- Brooke Kathryn Bowe
- Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
- Food Research Institute, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
| | - Travis Gwynn Wentz
- Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
| | - Brieana Marie Gregg
- Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
| | - William Howard Tepp
- Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
| | - Kristin Marie Schill
- Food Research Institute, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
| | - Shashi Sharma
- Division of Microbiology, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740, USA
| | - Sabine Pellett
- Department of Bacteriology, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
- Food Research Institute, University of Wisconsin-Madison, 1550 Linden Dr, Madison, WI 53706, USA
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Regulatory Networks Controlling Neurotoxin Synthesis in Clostridium botulinum and Clostridium tetani. Toxins (Basel) 2022; 14:toxins14060364. [PMID: 35737025 PMCID: PMC9229411 DOI: 10.3390/toxins14060364] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/16/2022] [Accepted: 05/21/2022] [Indexed: 12/30/2022] Open
Abstract
Clostridium botulinum and Clostridium tetani are Gram-positive, spore-forming, and anaerobic bacteria that produce the most potent neurotoxins, botulinum toxin (BoNT) and tetanus toxin (TeNT), responsible for flaccid and spastic paralysis, respectively. The main habitat of these toxigenic bacteria is the environment (soil, sediments, cadavers, decayed plants, intestinal content of healthy carrier animals). C. botulinum can grow and produce BoNT in food, leading to food-borne botulism, and in some circumstances, C. botulinum can colonize the intestinal tract and induce infant botulism or adult intestinal toxemia botulism. More rarely, C. botulinum colonizes wounds, whereas tetanus is always a result of wound contamination by C. tetani. The synthesis of neurotoxins is strictly regulated by complex regulatory networks. The highest levels of neurotoxins are produced at the end of the exponential growth and in the early stationary growth phase. Both microorganisms, except C. botulinum E, share an alternative sigma factor, BotR and TetR, respectively, the genes of which are located upstream of the neurotoxin genes. These factors are essential for neurotoxin gene expression. C. botulinum and C. tetani share also a two-component system (TCS) that negatively regulates neurotoxin synthesis, but each microorganism uses additional distinct sets of TCSs. Neurotoxin synthesis is interlocked with the general metabolism, and CodY, a master regulator of metabolism in Gram-positive bacteria, is involved in both clostridial species. The environmental and nutritional factors controlling neurotoxin synthesis are still poorly understood. The transition from amino acid to peptide metabolism seems to be an important factor. Moreover, a small non-coding RNA in C. tetani, and quorum-sensing systems in C. botulinum and possibly in C. tetani, also control toxin synthesis. However, both species use also distinct regulatory pathways; this reflects the adaptation of C. botulinum and C. tetani to different ecological niches.
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Lin Y, Jiang Y, Gong Z, Wang Y, Jiang M, Chen Q, Li C, Hu Q, Shi X. Investigation and Identification of Food Poisoning Caused by Clostridium botulinum Type B1 in Shenzhen, China. Foodborne Pathog Dis 2022; 19:226-231. [PMID: 35231189 DOI: 10.1089/fpd.2021.0060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Clostridium botulinum produces botulinum neurotoxins (BoNTs), which cause people who ingest them to become seriously ill and sometimes die. In recent years, sporadic food poisoning cases associated with C. botulinum have occurred across the world. In 2016, two men were admitted to our hospital in Shenzhen, China, with foodborne botulism. In this study, we report on these two typical C. botulinum-related food poisoning incidents and the steps taken to identify and characterize the causative pathogen. We characterized the bacterial pathogen isolated from the first patient using cooked meat medium and egg yolk agar bacterial cultures under anaerobic conditions, and morphologically identified the isolate using Gram staining. The in vivo bioassay results in mice showed that the minimum lethal dose of the BoNTs produced by our isolate was 0.001-0.0001 mg/mL (LD50 of the culture was estimated to be 1.5812 mg/kg). Whole genome sequencing (WGS) results showed that the isolate was identified as C. botulinum B1 Okra. The causative strain was successfully isolated from the intestinal lavage fluid collected from the initial patient.
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Affiliation(s)
- Yiman Lin
- Shenzhen Major Infectious Disease Control Key Laboratory, Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Yixiang Jiang
- Shenzhen Major Infectious Disease Control Key Laboratory, Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Zelong Gong
- School of Public Health, Southern Medical University, Guangzhou, China
| | - Yanli Wang
- The University of Hong Kong-Shenzhen Hospital, Shenzhen, China
| | - Min Jiang
- Shenzhen Major Infectious Disease Control Key Laboratory, Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Qiongcheng Chen
- Shenzhen Major Infectious Disease Control Key Laboratory, Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Chunlian Li
- Shenzhen Major Infectious Disease Control Key Laboratory, Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Qinghua Hu
- Shenzhen Major Infectious Disease Control Key Laboratory, Shenzhen Center for Disease Control and Prevention, Shenzhen, China
| | - Xiaolu Shi
- Shenzhen Major Infectious Disease Control Key Laboratory, Shenzhen Center for Disease Control and Prevention, Shenzhen, China
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