Structure of the full-length Clostridium difficile toxin B

Chen, Peng; Lam, Kwok Ho; Liu, Zheng; Mindlin, Frank A.; Chen, Baohua; Gutierrez, Craig; Huang, Lan; Zhang, Yongrong; Hamza, Therwa; Feng, Hanping; Matsui, Tsutomu; Bowen, Mark E.; Perry, Kay; Jin, Rongsheng

doi:10.1038/s41594-019-0268-0

Cited by 73 publications

(146 citation statements)

References 78 publications

(120 reference statements)

Supporting

Mentioning

121

Contrasting

Order By: Relevance

“…Initial analysis of the dataset revealed that approximately 50% of the SEMA6A dimers were bound to TcsL using this sample preparation approach. Consequently, 2D and 3D classification resulted in two homogenous datasets corresponding to the TcsL- Figure 3 The architecture of TcsL is similar to previously-determined structures of other clostridial toxins (8,(22)(23)(24) of SEMA6A, which is buried in a TcsL hydrophobic pocket formed by C1433, I1434, Y1471, A1486 and I1493. Indeed, expression of a SEMA6A M109D in SEMA6A knockout cells does not make the cells more sensitive to TcsL, in contrast to wild-type SEMA6A (Fig.…”

supporting

confidence: 65%

Identification of the C. sordellii lethal toxin receptor elucidates principles of receptor specificity in clostridial toxins

Lee

Beilhartz

Kucharska

et al. 2019

Preprint

View full text Add to dashboard Cite

Clostridium sordellii lethal toxin (TcsL) is responsible for an almost invariably lethal toxic shock syndrome associated with gynecological C. sordellii infections. Here, using CRISPR/Cas9 screening, we identify semaphorins SEMA6A and SEMA6B as the cellular receptors for TcsL and demonstrate that soluble extracellular SEMA6A can protect mice from TcsL-induced edema. A 3.3 Å cryo-EM structure shows that TcsL binds SEMA6A with the same region that the highly related C. difficile TcdB toxin uses to bind structurally unrelated Frizzled receptors. Remarkably, reciprocal mutations in this evolutionarily divergent surface are sufficient to switch receptor specificity between the toxins. Our findings establish semaphorins as physiologically relevant receptors for TcsL, and reveal the molecular basis for the difference in tissue targeting and disease pathogenesis between highly related toxins.Clostridium sordellii is an anaerobic gram-positive bacterium found in soil and in the gastrointestinal and vaginal tracts of animals and humans. C. sordellii is present in the rectal or vaginal tract of 3-4% of women, but vaginal colonization rate after childbirth or abortion is as high as 29% (1, 2). While the majority of carriers are asymptomatic, pathogenic C. sordellii infections arise rapidly and are highly lethal. Most C. sordellii infections occur in women following childbirth, medically induced abortion, or miscarriage, leading to a toxic shock syndrome with almost 100% mortality within days (1-4). The primary cause of the high mortality associated with C. sordellii infections is the lethal toxin TcsL (5), which belongs to the large clostridial toxin (LCT) family together with toxins from related species such as Clostridium difficile (6). LCTs enter the host cell by receptor-mediated endocytosis followed by translocation into the cytoplasm, where they potently modulate host cell function by glucosylating small Ras family GTPases (6).Although all LCTs are highly similar at the sequence level, they differ in their tissue specificity and in their effects on cell morphology, physiology, and viability. TcsL is most closely related to the C. difficile cytotoxin TcdB, sharing almost 90% sequence similarity. TcdB binds Frizzled family receptors FZD1/FZD2/FZD7 expressed in the colonic epithelium (7,8), the primary site of C. difficile infection. C. sordellii, however, does not infect or damage colonic epithelium, suggesting that TcsL binds a different cell-surface receptor.

show abstract

supporting

confidence: 65%

Identification of the C. sordellii lethal toxin receptor elucidates principles of receptor specificity in clostridial toxins

Lee

Beilhartz

Kucharska

et al. 2019

Preprint

View full text Add to dashboard Cite

show abstract

“…binding 55 , and E3 binding 54 were then analyzed in terms of their variation across subtypes. E3 binding residues were identified by analysis of PDB structure 6OQ5 54…”

Section: Sequence Clustering and Analysismentioning

confidence: 99%

“…FZD and bezlotoxumab variants also co-occur with each other. (b) Evolutionary conservation mapped to the protein structure of full length TcdB based on PDB 6OQ554 . Eight highly conserved surface patches are indicated, and additional details are inFig.…”

mentioning

confidence: 99%

Phylogenomics of 8,839Clostridioides difficilegenomes reveals recombination-driven evolution and diversification of toxin A and B

Mansfield

Tremblay

Zeng

et al. 2020

Preprint

View full text Add to dashboard Cite

AbstractClostridioides difficile is the major worldwide cause of antibiotic-associated gastrointestinal infection. A pathogenicity locus (PaLoc) encoding one or two homologous toxins, toxin A (TcdA) and toxin B (TcdB) is essential for C. difficile pathogenicity. However, toxin sequence variation poses major challenges for the development of diagnostic assays, therapeutics, and vaccines. Here, we present a comprehensive phylogenomic analysis 8,839 C. difficile strains and their toxins including 6,492 genomes that we assembled from the NCBI short read archive. A total of 5,175 tcdA and 8,022 tcdB genes clustered into 7 (A1-A7) and 12 (B1-B12) distinct subtypes, which form the basis of a new method for toxin-based subtyping of C. difficile. We developed a haplotype coloring algorithm to visualize amino acid variation across all toxin sequences, which revealed that TcdB has diversified through extensive homologous recombination throughout its entire sequence, and formed new subtypes through distinct recombination events. In contrast, TcdA varies mainly in the number of repeats in its C-terminal repetitive region, suggesting that recombination-mediated diversification of TcdB provides a selective advantage in C. difficile evolution. The application of toxin subtyping is then validated by classifying 351 C. difficile clinical isolates from Brigham and Women’s Hospital in Boston, demonstrating its clinical utility. Subtyping partitions TcdB into binary functional and antigenic groups generated by intragenic recombinations, including two distinct cell-rounding phenotypes, whether recognizing frizzled proteins as receptors, and whether can be efficiently neutralized by monoclonal antibody bezlotoxumab, the only FDA-approved therapeutic antibody. Our analysis also identifies eight universally conserved surface patches across the TcdB structure, representing ideal targets for developing broad-spectrum therapeutics. Finally, we established an open online database (DiffBase) as a central hub for collection and classification of C. difficile toxins, which will help clinicians decide on therapeutic strategies targeting specific toxin variants, and allow researchers to monitor the ongoing evolution and diversification of C. difficile.

show abstract

“…These are two large proteins that contain a common multi-modular domain structure described as the ABCD model (A: biological activity; B: binding; C: cutting; D: delivery) [14]. The crystal structure of toxin A and toxin B has recently been elucidated and reported [15,16]. The toxins are encoded by the tcdA and tcdB genes, respectively, located within a region known as the pathogenicity locus or PaLoc, a chromosomally integrated DNA sequence.…”

Section: Pathophysiology Of CDImentioning

confidence: 99%

Bezlotoxumab for Preventing Recurrent Clostridioides difficile Infection: A Narrative Review from Pathophysiology to Clinical Studies

et al. 2020

View full text Add to dashboard Cite

Clostridioides difficile infection (CDI) and recurrent CDI (rCDI) remain associated with a reduction in the patients' quality of life and with increased healthcare costs. Bezlotoxumab is a monoclonal antibody against toxin B of C. difficile, approved for prevention of rCDI. In this narrative review, we briefly discuss the pathophysiology of CDI and the mechanism of action of bezlotoxumab, as well as the available evidence from investigational and observational studies in terms of efficacy, effectiveness, and safety of bezlotoxumab for the prevention of rCDI. Overall, bezlotoxumab has proved efficacious in reducing the burden of rCDI, thereby providing clinicians with an important novel strategy to achieve sustained cure. Nonetheless, experiences outside randomized controlled trials (RCTs) remain scant, and mostly represented by case series without a control group. Along with the conduction of RCTs to directly compare bezlotoxumab with faecal microbiota transplantation (or to precisely evaluate the role of their combined use), further widening our post-marketing experience remains paramount to firmly guide the use of bezlotoxumab outside RCTs, and to clearly identify those real-life settings where its preventive benefits can be exploited most.

show abstract

Structure of the full-length Clostridium difficile toxin B

Cited by 73 publications

References 78 publications

Identification of the C. sordellii lethal toxin receptor elucidates principles of receptor specificity in clostridial toxins

Identification of the C. sordellii lethal toxin receptor elucidates principles of receptor specificity in clostridial toxins

Phylogenomics of 8,839Clostridioides difficilegenomes reveals recombination-driven evolution and diversification of toxin A and B

Bezlotoxumab for Preventing Recurrent Clostridioides difficile Infection: A Narrative Review from Pathophysiology to Clinical Studies

Contact Info

Product

Resources

About