Special Issue "Novel Aspects of Bacterial AB5-Toxins"

A special issue of Toxins (ISSN 2072-6651). This special issue belongs to the section "Bacterial Toxins".

Deadline for manuscript submissions: 31 January 2022.

Special Issue Editors

Prof. Dr. Holger Barth
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Guest Editor
Institut für Pharmakologie und Toxikologie, Universitätsklinikum Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
Special Issues and Collections in MDPI journals
Prof. Dr. Herbert Schmidt
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Guest Editor
Institute of Food Science and Biotechnologie, Department of Food Microbiology and -hygiene, University of Hohenheim, Garbenstrasse 28, 70599 Stuttgart, Germany

Special Issue Information

Dear Colleagues,

Bacterial AB5 toxins consist of a highly specialized group of composite proteins, which have been implicated in serious human diseases. Current important members of the bacterial AB5 toxin family are cholera toxin (Ctx) of Vibrio cholerae, pertussis toxin (Ptx) of Bordetella pertussis, Shiga toxin (Stx), subtilase cytotoxin (SubAB), and heat-labile Enterotoxin (Lt) of pathogenic Escherichia coli. More recently, other bacterial AB5 toxins have been described, such as ArtAB of Salmonella enterica serovar Typhi and Ecx of E. coli. AB5 toxins share a similar hexameric architecture, consisting of an enzymatic subunit (A) and five receptor-binding B subunits that form a pentamer. Whereas the enzymatic A subunits mediate the toxic effects in their eukaryotic target cells, the B subunits guide the holotoxin to the target cells by specific receptor binding and finally deliver the A subunits into the cytosol where they interact with their substrate molecules. Binding, uptake, and intracellular transport of AB5 toxins follow similar paths but are toxin-specific, as described in the literature.

During recent years, interesting new aspects of AB5 toxins concerning subunit structures, assembly, binding, uptake, and the AB5 paradigm have been revealed by several authors. Moreover, attractive novel approaches to specifically inhibit toxin uptake and thereby cell intoxication were reported. The aim of this Special Issue is to present novel aspects of AB5 toxins to get more detailed insights into the structure and function of this important group of protein exotoxins.

Prof. Dr. Holger Barth
Prof. Dr. Herbert Schmidt
Guest Editors

Manuscript Submission Information

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Keywords

  • AB5 toxins
  • Shiga toxin
  • subtilase cytotoxin
  • Pertussistoxin
  • Choleratoxin
  • subunit assembly
  • binding
  • translocation
  • function
  • inhibitors

Published Papers (2 papers)

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Research

Article
Combined Action of Shiga Toxin Type 2 and Subtilase Cytotoxin in the Pathogenesis of Hemolytic Uremic Syndrome
Toxins 2021, 13(8), 536; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins13080536 - 29 Jul 2021
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Abstract
Shiga toxin-producing E. coli (STEC) produces Stx1 and/or Stx2, and Subtilase cytotoxin (SubAB). Since these toxins may be present simultaneously during STEC infections, the purpose of this work was to study the co-action of Stx2 and SubAB. Stx2 + SubAB was assayed in [...] Read more.
Shiga toxin-producing E. coli (STEC) produces Stx1 and/or Stx2, and Subtilase cytotoxin (SubAB). Since these toxins may be present simultaneously during STEC infections, the purpose of this work was to study the co-action of Stx2 and SubAB. Stx2 + SubAB was assayed in vitro on monocultures and cocultures of human glomerular endothelial cells (HGEC) with a human proximal tubular epithelial cell line (HK-2) and in vivo in mice after weaning. The effects in vitro of both toxins, co-incubated and individually, were similar, showing that Stx2 and SubAB contribute similarly to renal cell damage. However, in vivo, co-injection of toxins lethal doses reduced the survival time of mice by 24 h and mice also suffered a strong decrease in the body weight associated with a lowered food intake. Co-injected mice also exhibited more severe histological renal alterations and a worsening in renal function that was not as evident in mice treated with each toxin separately. Furthermore, co-treatment induced numerous erythrocyte morphological alterations and an increase of free hemoglobin. This work shows, for the first time, the in vivo effects of Stx2 and SubAB acting together and provides valuable information about their contribution to the damage caused in STEC infections. Full article
(This article belongs to the Special Issue Novel Aspects of Bacterial AB5-Toxins)
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Article
Cytotoxic Effects of Recombinant StxA2-His in the Absence of Its Corresponding B-Subunit
Toxins 2021, 13(5), 307; https://0-doi-org.brum.beds.ac.uk/10.3390/toxins13050307 - 26 Apr 2021
Viewed by 814
Abstract
AB5 protein toxins are produced by certain bacterial pathogens and are composed of an enzymatically active A-subunit and a B-subunit pentamer, the latter being responsible for cell receptor recognition, cellular uptake, and transport of the A-subunit into the cytosol of eukaryotic target [...] Read more.
AB5 protein toxins are produced by certain bacterial pathogens and are composed of an enzymatically active A-subunit and a B-subunit pentamer, the latter being responsible for cell receptor recognition, cellular uptake, and transport of the A-subunit into the cytosol of eukaryotic target cells. Two members of the AB5 toxin family were described in Shiga toxin-producing Escherichia coli (STEC), namely Shiga toxin (Stx) and subtilase cytotoxin (SubAB). The functional paradigm of AB toxins includes the B-subunit being mandatory for the uptake of the toxin into its target cells. Recent studies have shown that this paradigm cannot be maintained for SubAB, since SubA alone was demonstrated to intoxicate human epithelial cells in vitro. In the current study, we raised the hypothesis that this may also be true for the A-subunit of the most clinically relevant Stx-variant, Stx2a. After separate expression and purification, the recombinant Stx2a subunits StxA2a-His and StxB2a-His were applied either alone or in combination in a 1:5 molar ratio to Vero B4, HeLa, and HCT-116 cells. For all cell lines, a cytotoxic effect of StxA2a-His alone was detected. Competition experiments with Stx and SubAB subunits in combination revealed that the intoxication of StxA2a-His was reduced by addition of SubB1-His. This study showed that the enzymatic subunit StxA2a alone was active on different cells and might therefore play a yet unknown role in STEC disease development. Full article
(This article belongs to the Special Issue Novel Aspects of Bacterial AB5-Toxins)
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