CHARACTERIZATION OF THE SOLUTION PROPERTIES AND CONFORMATION OF PNEUMOLYSIN, THE MEMBRANE-DAMAGING TOXIN OF STREPTOCOCCUS-PNEUMONIAE

Pneumolysin is a membrane-damaging toxin produced by Streptococcuspneumoniae. In order to understand fully the mode of action of this toxin, it is necessary to have an appreciation of the size, self-association behaviour and solution conformation of pneumolysin. A combination of analytical ultracentrifugation methodologies has shown that pneumolysin lacks self-association behaviour in solution and has provided a weight-average M(r)(M(w)BAR) of 52000 +/- 2000, which was in agreement with that derived from the amino acid sequence. By determining a sedimentation coefficient (s20,w0) of 3.35 +/- 0.10 S, it was possible to suggest a model for the gross solution conformation of pneumolysin monomers. Spectroscopic methods provide additional secondary and tertiary structure information.