Rabbit enterotoxaemia: Purification and preliminary characterisation of a toxin produced by Clostridium spiroforme

Fernie, D

doi:10.1016/0378-1097(84)90296-9

Cited by 4 publications

(6 citation statements)

References 3 publications

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“…S3–S5 d-f) representing 23, 21 and 19% cytotoxicity compared with the ΔPaLoc parental strain. These values were similar to those obtained following treatment with the CDT-minus control, in which CDTb present in the ΔPaLoc supernatant had not been proteolytically activated with trypsin and consequently could not enter the cells through receptor-mediated endocytosis [24,25]. Such treatments led to 25, 31 and 40 (Figs.…”

Section: Resultssupporting

confidence: 82%

Phosphorylation and functionality of CdtR in Clostridium difficile

2019

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The production of TcdA, TcdB and CDT in Clostridium difficile PCR ribotype 027, is regulated by the two-component system response regulator CdtR. Despite this, little is known about the signal transduction pathway leading to the activation of CdtR. In this study, we generated R20291ΔPalocΔ cdtR model strains expressing CdtR phospho-variants in which our predicted phospho-accepting Asp, Asp61 was mutated for Ala or Glu. The constructs were assessed for their ability to restore CDT production. Dephospho-CdtR-Asp61Ala was completely non-functional and mirrored the cdtR -deletion mutant, whilst phospho-CdtR-Asp61Glu was functional, possessing 38–52% of wild-type activity. Taken together, these data suggest that CdtR is activated by phosphorylation of Asp61. The same principles were applied to assess the function of PCR ribotype 078-derived CdtR, which was shown to be non-functional owing to polymorphisms present within its coding gene. Conversely, polymorphisms present within its promoter region, provide significantly enhanced promoter activity compared with its PCR ribotype 027 counterpart. To ensure our data were representative for each ribotype, we determined that the cdtR nucleotide sequence was conserved in a small library of eight PCR ribotype 027 clinical isolates and nineteen PCR ribotype 078 isolates from clinical and animal origin.

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Section: Resultssupporting

confidence: 82%

Phosphorylation and functionality of CdtR in Clostridium difficile

2019

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“…The isoelectric points of mature "A" components range from 5.2 (C. perfringens Ia) to a distinctly high 9.3 (C. difficile CDTa), while the "B" component range encompasses pH 4.5 (C. difficile CDTb) to 6.2 (C. botulinum C2II) (331). The cell-binding components are enzymatically inert (as ascertained by existing assays) and produced by the bacterium as precursor molecules, with isoelectric point shifts of less than 0.8 pH unit following activation by various serine-type proteases such as chymotrypsin, furin, or trypsin derived from the bacterium, host, or exogenous addition in vitro (122,211,325,417). The resultant loss of an N-terminal peptide (ϳ20 kDa) from a "B" precursor induces conformational changes that facilitate homoheptamerization, either in solution or on the cell surface, and subsequent docking with an "A" component(s).…”

Section: Biochemistry Genetics and Proteolytic Activationmentioning

confidence: 99%

Binary Bacterial Toxins: Biochemistry, Biology, and Applications of CommonClostridiumandBacillusProteins

Barth

Aktories

Popoff

et al. 2004

Microbiol Mol Biol Rev

375

388

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Certain pathogenic species of Bacillus and Clostridium have developed unique methods for intoxicating cells that employ the classic enzymatic “A-B” paradigm for protein toxins. The binary toxins produced by B. anthracis, B. cereus, C. botulinum, C. difficile, C. perfringens, and C. spiroforme consist of components not physically associated in solution that are linked to various diseases in humans, animals, or insects. The “B” components are synthesized as precursors that are subsequently activated by serine-type proteases on the targeted cell surface and/or in solution. Following release of a 20-kDa N-terminal peptide, the activated “B” components form homoheptameric rings that subsequently dock with an “A” component(s) on the cell surface. By following an acidified endosomal route and translocation into the cytosol, “A” molecules disable a cell (and host organism) via disruption of the actin cytoskeleton, increasing intracellular levels of cyclic AMP, or inactivation of signaling pathways linked to mitogen-activated protein kinase kinases. Recently, B. anthracis has gleaned much notoriety as a biowarfare/bioterrorism agent, and of primary interest has been the edema and lethal toxins, their role in anthrax, as well as the development of efficacious vaccines and therapeutics targeting these virulence factors and ultimately B. anthracis. This review comprehensively surveys the literature and discusses the similarities, as well as distinct differences, between each Clostridium and Bacillus binary toxin in terms of their biochemistry, biology, genetics, structure, and applications in science and medicine. The information may foster future studies that aid novel vaccine and drug development, as well as a better understanding of a conserved intoxication process utilized by various gram-positive, spore-forming bacteria

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“…3). This residual toxicity, however, was not CDT-mediated, since the CDT-minus control comprising R20291ΔPaLoc supernatant without the proteolytic activation of CdtB, and which consequently could not mediate cellular entry of CdtA [11], [12], also led to an average of 25.6 rounded cells (Fig. S3j−l), thus demonstrating the involvement of other non-toxin virulence factors.…”

mentioning

confidence: 99%