Pore-forming toxins Streptolysin

When alamethicin is added to a ternary vesicle system comprising PDA, phospholipid, and lipopolysaccharide (LPS), the addition of polymyxin, an LPS-binding antibiotic, sensitizes the vesicles to alamethicin (Katz et al. 2003). Cholesterol-containing PDA liposomes have been used to colorimetrically detect streptolysin O, a cholesterol-dependent pore-forming toxin (Ma and Cheng 2005). 

Permeabilized cells allow the study of intracellular processes in situ under conditions which are believed to be close to the physiological situation in intact cells. Permeabilization by bacterial pore-forming toxins, alpha-toxin and streptolysin O (SLO) is now a widely accepted approach in the functional analysis of intracellular organelles. 

Bhakdi S, Bayley H, Valeva A etal. (1996) Staphylococcal alpha-toxin, streptolysin O, and Escherichia coli hemolysin prototypes of pore forming bacterial cytoly-sins. In Arch Microbiol 165 73-79. 

Toxins that act directly on cell membranes, called cytolytic toxins, disturb and ultimately kill the target cells. Produced by many organisms (e.g., bacteria, fungi, plants, fish, and snakes), cytolytic toxins may cause damage in several ways. For example, streptolysin O (67,000 D), produced by the bacterium Streptococcus pyogenes, causes pores to form in the target cell membranes. Affected cells are rapidly lysed because the cell membrane is much more permeable to ions such as Na+. Streptolysin O is believed to cause some of the damage in rheumatic fever. 

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