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Special Issue "Bacterial Pore-Forming Toxins"

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

Deadline for manuscript submissions: 30 September 2018

Special Issue Editor

Guest Editor
Dr. Peter A. Keyel

Department of Biological Sciences, Texas Tech University, Box 43131 Lubbock, TX 79409 USA
Website | E-Mail
Interests: cholesterol-dependent cytolysin; membrane repair; inflammasome; macrophage; Dnase1L3

Special Issue Information

Dear Colleagues,

Pore-forming toxins (PFTs) are the largest family of bacterial toxins. They are extensively involved in the virulence of many lethal Gram positive and Gram negative bacterial infections. In some cases, their impacts appear to be independent of target cell lysis, suggesting that PFTs may affect target cells in multiple ways. Similarly, nonpathogenic bacteria also utilize a range of PFTs, indicating that PFTs provide bacteria with a survival advantage beyond pathogenesis. The evolutionary advantages of PFTs are not limited to bacteria. Bacterial PFTs bear strong structural and three-dimensional similarities to PFTs used by other organisms, and have served effectively as tools for answering broad, fundamental questions about PFT structure and mechanism of action. Three such broad outstanding questions in the field are: How do bacterial PFTs promote bacterial fitness beyond lysis of target cells? What mechanisms do competing bacteria, hosts and other organisms use to react to bacterial PFTs? Which insights and mechanisms from bacterial PFTs are also relevant to PFTs from humans and other organisms?

This Special Issue will focus on the interaction of bacterial pore forming toxins with their targets, the functional outcomes of these interactions, and target responses to these toxins. Nonlethal toxin-target interactions, and novel insights into toxin structure/function are areas of special interest.

Dr. Peter A. Keyel
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a double-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Toxins is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • pore-forming toxin
  • cholesterol-dependent cytolysin
  • hemolysin
  • host-pathogen interaction
  • membrane repair
  • cell death

Published Papers (3 papers)

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Research

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Open AccessArticle Arcanobacterium haemolyticum Phospholipase D Enzymatic Activity Promotes the Hemolytic Activity of the Cholesterol-Dependent Cytolysin Arcanolysin
Received: 26 April 2018 / Revised: 14 May 2018 / Accepted: 18 May 2018 / Published: 23 May 2018
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Abstract
Arcanolysin, produced by the human pathogen Arcanobacterium haemolyticum, is a cholesterol-dependent cytolysin. To mediate the pore-formation process, arcanolysin is secreted by A. haemolyticum and then must interact with cholesterol embedded within a host membrane. However, arcanolysin must compete with membrane components, such
[...] Read more.
Arcanolysin, produced by the human pathogen Arcanobacterium haemolyticum, is a cholesterol-dependent cytolysin. To mediate the pore-formation process, arcanolysin is secreted by A. haemolyticum and then must interact with cholesterol embedded within a host membrane. However, arcanolysin must compete with membrane components, such as the phospholipid sphingomyelin, to interact with cholesterol and form pores. Cholesterol forms transient hydrogen bonds with the extracellular portion of sphingomyelin, shielding cholesterol from extracellular factors, including arcanolysin. A. haemolyticum also produces a sphingomyelin-specific phospholipase D, which removes the choline head from sphingomyelin, leaving cyclic-ceramide phosphate and eliminating the potential for cholesterol sequestration. We hypothesized that the enzymatic activity of phospholipase D decreases sphingomyelin-mediated cholesterol sequestration and increases cholesterol accessibility for arcanolysin. Using purified arcanolysin and phospholipase D, we demonstrate that the enzymatic activity of phospholipase D is necessary to promote arcanolysin-mediated hemolysis in both time- and concentration-dependent manners. Phospholipase D promotion of arcanolysin-mediated cytotoxicity was confirmed in Detroit 562 epithelial cells. Furthermore, we determined that incubating phospholipase D with erythrocytes corresponds with an increase in the amount of arcanolysin bound to host membranes. This observation suggests that phospholipase D promotes arcanolysin-mediated cytotoxicity by increasing the ability of arcanolysin to bind to a host membrane. Full article
(This article belongs to the Special Issue Bacterial Pore-Forming Toxins)
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Open AccessArticle Acid Sphingomyelinase Promotes Cellular Internalization of Clostridium perfringens Iota-Toxin
Received: 21 April 2018 / Revised: 14 May 2018 / Accepted: 18 May 2018 / Published: 20 May 2018
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Abstract
Clostridium perfringens iota-toxin is a binary actin-ADP-ribosylating toxin composed of the enzymatic component Ia and receptor binding component Ib. Ib binds to a cell surface receptor, forms Ib oligomer in lipid rafts, and associates with Ia. The Ia-Ib complex then internalizes by endocytosis.
[...] Read more.
Clostridium perfringens iota-toxin is a binary actin-ADP-ribosylating toxin composed of the enzymatic component Ia and receptor binding component Ib. Ib binds to a cell surface receptor, forms Ib oligomer in lipid rafts, and associates with Ia. The Ia-Ib complex then internalizes by endocytosis. Here, we showed that acid sphingomyelinase (ASMase) facilitates the cellular uptake of iota-toxin. Inhibitions of ASMase and lysosomal exocytosis by respective blockers depressed cell rounding induced by iota-toxin. The cytotoxicity of the toxin increased in the presence of Ca2+ in extracellular fluids. Ib entered target cells in the presence but not the absence of Ca2+. Ib induced the extracellular release of ASMase in the presence of Ca2+. ASMase siRNA prevented the cell rounding induced by iota-toxin. Furthermore, treatment of the cells with Ib resulted in the production of ceramide in cytoplasmic vesicles. These observations showed that ASMase promotes the internalization of iota-toxin into target cells. Full article
(This article belongs to the Special Issue Bacterial Pore-Forming Toxins)
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Review

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Open AccessReview Membrane Repair Mechanisms against Permeabilization by Pore-Forming Toxins
Received: 24 May 2018 / Revised: 4 June 2018 / Accepted: 7 June 2018 / Published: 9 June 2018
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Abstract
Permeabilization of the plasma membrane represents an important threat for any cell, since it compromises its viability by disrupting cell homeostasis. Numerous pathogenic bacteria produce pore-forming toxins that break plasma membrane integrity and cause cell death by colloid-osmotic lysis. Eukaryotic cells, in turn,
[...] Read more.
Permeabilization of the plasma membrane represents an important threat for any cell, since it compromises its viability by disrupting cell homeostasis. Numerous pathogenic bacteria produce pore-forming toxins that break plasma membrane integrity and cause cell death by colloid-osmotic lysis. Eukaryotic cells, in turn, have developed different ways to cope with the effects of such membrane piercing. Here, we provide a short overview of the general mechanisms currently proposed for plasma membrane repair, focusing more specifically on the cellular responses to membrane permeabilization by pore-forming toxins and presenting new data on the effects and cellular responses to the permeabilization by an RTX (repeats in toxin) toxin, the adenylate cyclase toxin-hemolysin secreted by the whooping cough bacterium Bordetella pertussis, which we have studied in the laboratory. Full article
(This article belongs to the Special Issue Bacterial Pore-Forming Toxins)
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