The role of cholesterol in the activity of pneumolysin, a bacterial protein toxin

Nöllmann, M., Gilbert, R., Mitchell, T., Sferrazza, M. and Byron, O. (2004) The role of cholesterol in the activity of pneumolysin, a bacterial protein toxin. Biophysical Journal, 86(5), pp. 3141-3151. (doi: 10.1016/S0006-3495(04)74362-3) (PMID:15111427) (PMCID:PMC1304179)

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Abstract

The mechanism via which pneumolysin (PLY), a toxin and major virulence factor of the bacterium Streptococcus pneumoniae, binds to its putative receptor, cholesterol, is still poorly understood. We present results from a series of biophysical studies that shed light on the interaction of PLY with cholesterol in solution and in lipid bilayers. PLY lyses cells whose walls contain cholesterol. Using standard hemolytic assays we have demonstrated that the hemolytic activity of PLY is inhibited by cholesterol, partially by ergosterol but not by lanosterol and that the functional stoichiometry of the cholesterol-PLY complex is 1:1. Tryptophan (Trp) fluorescence data recorded during PLY-cholesterol titration studies confirm this ratio, reveal a significant blue shift in the Trp fluorescence peak with increasing cholesterol concentrations indicative of increasing nonpolarity in the Trp environment, consistent with cholesterol binding by the tryptophans, and provide a measure of the affinity of cholesterol binding: Kd = 400 ± 100 nM. Finally, we have performed specular neutron reflectivity studies to observe the effect of PLY upon lipid bilayer structure.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Byron, Professor Olwyn and Nollmann, Marcelo and Mitchell, Professor Timothy
Authors: Nöllmann, M., Gilbert, R., Mitchell, T., Sferrazza, M., and Byron, O.
College/School:College of Medical Veterinary and Life Sciences > School of Life Sciences
College of Medical Veterinary and Life Sciences > School of Infection & Immunity
Journal Name:Biophysical Journal
Publisher:Elsevier (Cell Press)
ISSN:0006-3495
ISSN (Online):1542-0086

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