Clostridium perfringens Enterotoxin: The Toxin Forms Highly Cation-Selective Channels in Lipid Bilayers

Roland Benz,Michel Popoff

doi:10.3390/toxins10090341

Roland Benz, Michel Popoff

Open Access

https://doi.org/10.3390/toxins10090341

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Journal: Toxins	Publication Date: Aug 22, 2018
Citations: 10	License type: CC BY 4.0

Affiliation: Constructor University, Institut Pasteur

Abstract

One of the numerous toxins produced by Clostridium perfringens is Clostridium perfringens enterotoxin (CPE), a polypeptide with a molecular mass of 35.5 kDa exhibiting three different domains. Domain one is responsible for receptor binding, domain two is involved in hexamer formation and domain three has to do with channel formation in membranes. CPE is the major virulence factor of this bacterium and acts on the claudin-receptor containing tight junctions between epithelial cells resulting in various gastrointestinal diseases. The activity of CPE on Vero cells was demonstrated by the entry of propidium iodide (PI) in the cells. The entry of propidium iodide caused by CPE was well correlated with the loss of cell viability monitored by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test. CPE formed ion-permeable channels in artificial lipid bilayer membranes with a single-channel conductance of 620 pS in 1 M KCl. The single-channel conductance was not a linear function of the bulk aqueous salt concentration indicating that point-negative charges at the CPE channel controlled ion transport. This resulted in the high cation selectivity of the CPE channels, which suggested that anions are presumably not permeable through the CPE channels. The possible role of cation transport by CPE channels in disease caused by C. perfringens is discussed.

Highlights

Clostridium perfringens is a ubiquitous spore-forming anaerobic bacterium which is responsible for various diseases in humans and animals including gangrene, and gastro-intestinal diseases
C. perfringens enterotoxin (CPE) activity on Vero cells was checked by monitoring the entry of propidium iodide (PI) as already tested with the mouse carcinoma cell line FM3a [37] or with other pore-forming toxins such as C. perfringens epsilon toxin (ETX) which form small pores in the plasma membrane [38]
Entry of propidium iodide was monitored by spectrofluorimetry and cell viability by the MTT test

Summary

Introduction

Clostridium perfringens is a ubiquitous spore-forming anaerobic bacterium which is responsible for various diseases in humans and animals including gangrene, and gastro-intestinal diseases (food poisoning diarrhea, enteritis, necrotic enteritis, and enterotoxemia). C. perfringens enterotoxin (CPE) is the causative toxin of food poisoning diarrhea and enteritis in humans and more rarely for enteritis in animals. A few number of C. perfringens strains (about 5%) contain the cpe gene and produce CPE. Most of C. perfringens type E possess a silent cpe, but some strains express a functional variant CPE [4,5]. CPE sequence is almost identical in all strains except in C. perfringens type E containing a variant CPE [2]. In most C. perfringens type A strains

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