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Ostreolysin A/Pleurotolysin B and Equinatoxins: Structure, Function and Pathophysiological Effects of These Pore-Forming Proteins

Institute of Preclinical Sciences, Veterinary Faculty, University of Ljubljana; 1115-Ljubljana, Slovenia
Laboratory for Cell Physiology and Toxinology, Institute of Pathophysiology, School of Medicine, University of Ljubljana, P.O. Box 11, 1105-Ljubljana, Slovenia
DRF/Institut de Sciences de la Vie Frédéric Joliot/SIMOPRO, CEA de Saclay, and Institut des Neurosciences Paris-Saclay (Neuro-PSI), UMR 9197 CNRS/Université Paris-Sud, 91190 Gif-sur-Yvette, France
Author to whom correspondence should be addressed.
Academic Editor: Michel R. Popoff
Toxins 2017, 9(4), 128;
Received: 13 February 2017 / Revised: 30 March 2017 / Accepted: 31 March 2017 / Published: 5 April 2017
(This article belongs to the Section Bacterial Toxins)
PDF [274 KB, uploaded 5 April 2017]


Acidic ostreolysin A/pleurotolysin B (OlyA/PlyB, formerly known as ostreolysin (Oly), and basic 20 kDa equinatoxins (EqTs) are cytolytic proteins isolated from the edible mushroom Pleurotus ostreatus and the sea anemone Actinia equina, respectively. Both toxins, although from different sources, share many similar biological activities: (i) colloid-osmotic shock by forming pores in cellular and artificial membranes enriched in cholesterol and sphingomyelin; (ii) increased vascular endothelial wall permeability in vivo and perivascular oedema; (iii) dose-dependent contraction of coronary vessels; (iv) haemolysis with pronounced hyperkalaemia in vivo; (v) bradycardia, myocardial ischemia and ventricular extrasystoles accompanied by progressive fall of arterial blood pressure and respiratory arrest in rodents. Both types of toxins are haemolytic within nanomolar range concentrations, and it seems that hyperkalaemia plays an important role in toxin cardiotoxicity. However, it was observed that the haemolytically more active EqT III is less toxic than EqT I, the most toxic and least haemolytic EqT. In mice, EqT II is more than 30 times more toxic than OlyA/PlyB when applied intravenously. These observations imply that haemolysis with hyperkalaemia is not the sole cause of the lethal activity of both toxins. Additional mechanisms responsible for lethal action of the two toxins are direct effects on heart, coronary vasoconstriction and related myocardial hypoxia. In this review, we appraise the pathophysiological mechanisms related to the chemical structure of OlyA/PlyB and EqTs, as well as their toxicity. View Full-Text
Keywords: ostreolysin A/pleurotolysin B; equinatoxins; pore-forming proteins; biological effects ostreolysin A/pleurotolysin B; equinatoxins; pore-forming proteins; biological effects
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Frangež, R.; Šuput, D.; Molgó, J.; Benoit, E. Ostreolysin A/Pleurotolysin B and Equinatoxins: Structure, Function and Pathophysiological Effects of These Pore-Forming Proteins. Toxins 2017, 9, 128.

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