Binding of cholesterol by sulfhydryl-activated cytolysins

Abstract

The binding of cholesterol by pneumolysin, alveolysin, and streptolysin 0 has been demonstrated. The properties of the cytolysin-cholesterol interaction parallel those of cytolysin-erythrocyte interaction in that the reaction is rapid, temperature independent, decreased at elevated pH, and shows the same specificity with respect to other related sterols. However, oxidized or p-hydroxymercuribenzoate-treated toxin showed no decrease in cholesterol-binding activity, whereas the ability of cytolysin to bind to erythrocytes was modified by such treatment. One of the several properties common to that group of cytolytic agents known as the sulflydryl (or thiol)-activated toxins is sensitivity to inhibition by cholesterol and certain related sterols (see review by Bernheimer, 4). These agents act only on cells containing cholesterol (3), and it has been shown with one member ofthe group, cereolysin, that the interaction of toxin with liposomes depends on their cholesterol content (6). The work cited above supports the hypothesis that target cell membrane cholesterol is the receptor for the sulfhydryl-activated toxins. Although several reports of in vitro interactions between purified sulfhydryl-activated toxins and sterol dispersions h4ve appeared (7, 18, 21), there has been no direct demonstration of the binding of pure toxin with cholesterol. In the present communication we present evidence for such a binding and describe some properties of the system. MATERIALS AND METHODS Reagents. Cholesterol (cholest-5-en-3,8-ol) was obtained from Sigma Chemical Co. and from Steraloids, Ltd, [3H]cholesterol with a specific activity of 50 Ci/ mmol from New England Nuclear Corp. and the Commissariat de l'Energie Atomique (France), epicholesterol (cholest-5-en-3a-ol) and 7-dehydrocholesterol (cholsta-5,7-dien-3,8-ol) from Schwartz/Mann; bovine serum albumin from Pentex Biochemical; cytochrome c from Mann Research Laboratories; p-hydroxymercuribenzoate (pHMB) from Sigma Chemical Co.; oxidized dithiothreitol (DTT) from Calbiochem; and reduced DTT from Koch Light Laboratories. Purification of cytolysins. Pneumolysin was purified and titrated as described previously (11, 12

SpsA, a novel pneumococcal surface protein with specific binding to secretory Immunoglobulin A and secretory component

“…Because of increasing antibiotic resistance among pneumococci and the suboptimal efficacy of polysaccharide vaccine, the interest has shifted towards pneumococcal proteins. Many proteins, such as autolysin (Garcia et al, 1986;Lock et al, 1992), neuraminidase (Berry et al, 1988;Lock et al, 1988), pneumococcal surface adhesin A (PsaA; Sampson et al, 1994), IgA1 protease (Male, 1979;Poulsen et al, 1996), peptide permeases , pneumolysin (Johnson et al, 1980;Paton, 1996) and pneumococcal surface protein A (PspA; Briles et al, 1988; have been identified and characterized. Among these, pneumolysin and PspA have been studied in detail.…”

Listeriolysin O: cholesterol inhibits cytolysis but not binding to cellular membranes

“…The property all thiol-activated toxins have in common is that preincubation with low amounts of cholesterol inhibits haemolytic activity as well as cytolysis of eukaryotic cells. Thus, it is has been suggested that cholesterol is the primary receptor on host cell membranes (Duncan and Schlegel, 1975;Prigent and Alouf, 1976;Jonson et al, 1980). According to this line, inhibition of cytolysis was assumed to be due to occupancy of the cholesterol binding site by free cholesterol.…”

Modulation of coronavirus‐mediated cell fusion by homeostatic control of cholesterol and fatty acid metabolism

“…Cholesterol plays an important role in determining the physical properties and functions of animal cell membranes. In addition to having a modulating effect on membrane fluidity and permeability [Demel et al, 19721, there is evidence that cholesterol may interact directly with certain membrane proteins [Johnson et al, 1980;Asano and Asano, 19881 and possibly regulate their functional activity [McMurchie, 1988;Asano and Asano, 19881. Cholesterol is a n important dietary lipid and has been shown to modulate resistance of mice to infections by some bacteria and viruses, including Listeria monocytogenes [Kos et al, 1979;Kos et al, 19841 and Coxsackie B virus [Campbell et al, 19821 and also MHV-3 [Pereira et al, 19871. MHV-3 is strongly hepatotropic in Balb/c mice but causes only a mild liver infection in A/J mice.…”