Entero-cytolysin (EC) from Vibrio cholerae non-O1 (some properties and pore-forming activity)

A thermolabile extracellular entero-cytolysin (EC) from Vibrio cholerae non-O1 was purified by ammonium sulphate fractionation, DE-52 cellulose ion exchange chromatography, gel-filtration on Ultrogel AcA-44 and high performance liquid chromatography on a Mono Q. The purified EC had a molecular weight of 63 kD and an isoelectric point of 6.2. It was not inactivated by cholesterol or 5,5'-dithio-bis(2-nitrobenzoic acid), nor activated by dithiothreitol. EC had no immunological cross-reactivity with cholera toxin. The EC caused fluid accumulation in the intestines of infant rabbits, death of mice by intravenous injection, and increased vascular permeability in the paw oedema test in mice. V. cholerae non-O1 EC lysed erythrocytes from various species and cultured cells (CHO, L-929, L-41, HEp-2, Vero, MDCK and BHK-21). In contrast to cholera toxin, EC caused crude destruction of target cells. The EC caused hemolysis by a colloid-osmotic mechanism due to the formation of hydrophilic pores of 1.8-2.0 nm diameter in the cell membrane. This EC also was able to open pores in lipid membranes. The induced channels were anion-selective and had a diameter of 1.8-2.0 nm.