C. difficile, B Subunit Binary Toxin (aa 209-876)

Name: C. difficile, B Subunit Binary Toxin (aa 209-876)
SKU: DAGB142
Rating: 5 (1 reviews)

Clostridium difficile Binary Toxin (B subunit) (aa 209-876), recombinant protein from E. coli

COA

SDS

Datasheet

Summary

Target

CDTb

Nature

Recombinant

Tag/Conjugate

Unconjugated

Molecular Weight

70 kDa

Format

Liquid

Concentration

Batch dependent - please inquire should you have specific requirements

Buffer

30mM Tris, 300mM NaCl, pH8.5

Preservative

None

Storage

Store at -20°C

Introduction

Binary toxin (CDT) is frequently observed in Clostridium difficile strains associated with increased severity of C. difficile infection (CDI). CDT belongs to the family of binary ADP-ribosylating toxins consisting of two separate toxin components: CDTa, the enzymatic ADP-ribosyltransferase which modifies actin, and CDTb which binds to host cells and translocates CDTa into the cytosol. CDTb is activated by serine proteases and binds to lipolysis stimulated lipoprotein receptor. ADP-ribosylation induces depolymerization of the actin cytoskeleton. Toxin-induced actin depolymerization also produces microtubule-based membrane protrusions which form a network on epithelial cells and increase bacterial adherence.

Keywords

Clostridium difficile; Binary toxin; CDTb

Citations

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Background

Clostridium difficile (C. difficile) is a Gram-positive anaerobic pathogen that primarily spreads through the fecal-oral route, rapidly increasing infection rates in hospitals and nursing homes. It causes nearly 50,000 deaths annually in the United States and Europe and has been classified by the Centers for Disease Control and Prevention (CDC) as one of the five most urgent threats to human health. In addition to primarily releasing clostridial toxins: enterotoxin TsdA and TsdB, highly virulent strains also release a potent AB-type binary toxin called B binary toxin (CDT), which is a major virulence factor in fatal C. difficile infections (CDI).

CDT consists of two independent proteins, CDTa and CDTb. The B subunit is responsible for delivery and has the ability to bind to target cell surfaces, while the A subunit, as an enzyme component, enters the cytoplasm through endocytosis, attacking actin cells to their death and causing clinical symptoms. While the A subunit translocates, the B subunit alone can cause cytoplasmic membrane perforation, leading to morphological changes in Vero human colonic epithelial cells CaCo-2, resulting in cytotoxicity. CDT intoxication induces an inflammatory response, damaging the structure and function of the host intestinal epithelial cells, leading to severe diarrhea, pseudomembranous colitis, and toxic megacolon complications, which can be life-threatening. Although it is known that CDT disrupts the actin cytoskeleton and damages epithelial tissues to induce inflammation, the specific impacts remain unclear and require further research to elucidate its interactions with the host.

Hypothetical Mechanism of CDT Entry into Cells (Abeyawardhane DL , 2021) Figure 1. Proposed Mechanism of CDT Cellular Entry (Source:Abeyawardhane DL , et al., 2021)

Current prevention and treatment methods for CDI are limited, with common approaches being antibiotic therapy. However, this method has significant limitations; on one hand, the emergence of resistance makes it ineffective in preventing recurrence, and on the other hand, it can lead to an imbalance in the gut microbiota, causing an overgrowth of C. difficile. Developing new, effective alternative therapies is crucial. Currently, a human monoclonal antibody, bezlotoxumab, planned for CDI prevention, has entered clinical trials, and some pharmacological inhibitors, such as pore-blocking agents chloroquine and its derivatives, have been shown to alleviate CDTb intoxication specifically.

Alternative Names

B Subunit Binary Toxin
C. difficile Binary Toxin B Subunit
CDTb
Clostridium difficile toxin

References

1. Abeyawardhane DL , et al., The Importance of Therapeutically Targeting the Binary Toxin from Clostridioides difficile. International Journal of Molecular Sciences . 2021; 22(6):2926.

Documents

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References

Sensory Processing and Gastrointestinal Manifestations in Autism Spectrum Disorders: No Relation toClostridium difficile

JOURNAL OF MOLECULAR NEUROSCIENCE

Authors: Khalil, Mona; Azouz, Hanan Galal; Ahmed, Shwikar AbdelSalam; Gad, Hala Ali; Omar, Omneya Magdy

Abstract

The role of the gut microbiota in triggering autism is a rapidly emerging field of research. Gut microbiota have been incriminated because autistic children often have gastrointestinal symptoms. Pathogenic gut bacteria in children with autism spectrum disorders (ASD) have been reported. The present study aimed to assessClostridium difficilein the stool of children with ASD and its relation to gastrointestinal (GI) comorbidities, autism severity, and sensory impairment. The study included 58 ASD patients, 45 of their neurotypical siblings, and 45 unrelated controls. Childhood Autism Rating Scale (CARS) was used to assess the severity of autism. Sensory problems were evaluated using the Short Sensory Profile (SSP). GI symptoms were assessed with a modified six-item GI Severity Index (6-GSI) questionnaire. Quantitative real-time PCR was done for the detection and quantitation ofC. difficileand its toxins A and B.C. difficilewas detected in 25.9%, 40%, and 15.6% of ASD cases, siblings, and unrelated control respectively. Regarding toxin A and B production, 73.3%, 77.8%, and 71.4% ofC. difficilein positive ASD, siblings, and unrelated control cases respectively were toxigenic. There was no statistically significant difference between the three groups as regardsC. difficilequalitative, quantitative, and toxin production results. In conclusion,C. difficileis not specifically prevalent in the gut of children with ASD. Although most of the strains are toxigenic, there were no GI symptoms in the control groups and no statistically significant association with GI Severity Index in autistic cases. Gastrointestinal dysfunction and sensory impairment are common comorbidities in ASD.

Phenotypic characterisation of Clostridium difficile PCR ribotype 251, an emerging multi-locus sequence type clade 2 strain in Australia

ANAEROBE

Authors: Hong, Stacey; Knight, Daniel R.; Chang, Barbara; Carman, Robert J.; Riley, Thomas V.

Abstract

The global emergence of epidemic Clostridium difficile PCR ribotype (RT) 027 prompted enhanced surveillance of emerging strains. Recently, there have been reports of severe C. difficile infection in Australia caused by an unusual strain of C. difficile not seen previously. Identified as PCR RT251, this strain produces toxins A (TcdA) and B (TcdB), as well as binary toxin (CDT), and shares a common phylogenetic lineage with RT027. In this study, C. difficile RT251 strains were sourced from various geographical locations and potential virulence factors were evaluated and compared to that of control strains, CD630, VPI10463 and R20291 in vitro. C. difficile RT251 strains were motile, germinated and sporulated efficiently, despite producing significantly less TcdA and TcdB compared to all control strains. Genomic analyses revealed three multi-locus sequence types (MLSTs 188, 231 and 365) with four to five loci variants compared to RT027 (ST1) all MLST clade 2. C. difficile RT251 strains were susceptible to metronidazole, vancomycin and moxifloxacin, a fluoroquinolone antimicrobial to which RT027 strains are often resistant. Further studies using whole-genome sequencing are required to determine additional virulence factors that may contribute to the pathogenicity of C. difficile RT251 strains. (C) 2019 Elsevier Ltd. All rights reserved.