Thiol-independent activity of a cholesterol-binding enterohemolysin produced by enteropathogenic Escherichia coli

Abstract

Enterohemolysin produced by Escherichia coli associated with infant diarrhea showed characteristics similar to those of thiol-activated hemolysins produced by Gram-positive bacteria, including inactivation by cholesterol, lytic activity towards eukaryotic cells and thermoinstability. However, enterohemolysin activity was not inactivated by oxidation or by SH group-blocking agents (1 mM HgCl 2 , 1 mM iodoacetic acid) and the hemolysin (100 µg/ml) was not lethal to mice, in contrast to the lethality of the thiol-activated hemolysin family to animals. Earlier reports showed that intravenous injection of partially purified streptolysin O preparations (0.2 µg) was rapidly lethal to mice. These results suggest that E. coli enterohemolysin is not a thiol-activated hemolysin, despite its ability to bind cholesterol, probably due to the absence of free thiol-group(s) that characterize the active form of the thiol-activated hemolysin molecule.

The ability of haemolysins expressed by atypical enteropathogenic Escherichia coli to bind to extracellular matrix components

“…2). This observation differs from previous reports, which describe the lack of haemolytic activity in the culture supernatant of strain C3888 (Beutin et al 1990, Figueiredo et al 2003. However, these authors detected such activity in disrupted bacterial cells collected by centrifugation.…”

Induction of apoptosis in Caco-2 and HT-29 human intestinal epithelial cells by enterohemolysin produced by classic enteropathogenic Escherichia coli

“…Enterohemolysin (EHly) was purified as described by Figueiredo et al . (2003b) from EHly produced by E. coli strain C3888 (O 26: H − ), kindly supplied by Dr. L. Beutin (Robert Koch Institute, Berlin, Germany) and was used in EHly purification, as described by (Figueiredo et al . 2003b).…”

“…Enterohemolysin Enterohemolysin (EHly) was purified as described by Figueiredo et al (2003b) from EHly produced by E. coli strain C3888 (O 26: H ) ), kindly supplied by Dr. L. Beutin (Robert Koch Institute, Berlin, Germany) and was used in EHly purification, as described by (Figueiredo et al 2003b). After many assays, we have determined that 0AE3 M of sodium sulfate or 0AE01% Triton X-100 are the best additive concentrations to improve and to stabilize the hemolytic activity of purified EHly, as proposed by Kashino (2003).…”

“…The cytotoxic activity of EHly had been reported in animals and human cultured cells lines (Beutin et al 1989(Beutin et al , 1998Figueiredo et al 2003b) with morphological changes, including cell rounding and detachment of the cell layer, as described for verotoxin by Konowalchuk et al (1977). However, a detailed study of the intracellular alterations by the EHly is still lacking.…”

Toxins of Locus of Enterocyte Effacement-Negative Shiga Toxin-Producing Escherichia coli

“…Whether pore formation occurs in an oligomeric form, such as that described for the Staphylococcus aureus ’ α-hemolysis, or in a monomeric way is still unknown. The same is true for the mechanism which is needed to form the first contact with the membrane of erythrocytes and eukaryotic cells, both of which are the typical target cells of EHEC-Hly [ 148 , 149 ]. In addition, and as something that is similar to all toxins of the RFX family, EHEC-Hly requires post-transformational activation by fatty acylation of specific lysine residues [ 150 ].…”