EN
The article contains information regarding the similarities and differences between proteins of the thiol-activated cytolysins family (TACY). Members of this group of haemolysins are produced by several species of Gram-positive bacteria (Listeria spp., Streptococcus spp., Bacillus spp., Clostridium spp.,) and also by Gram-negative Klebsiella spp.. Their cytolytic activity is sensitive to oxygen and can be restored by adding reducing compounds. TACY bind to cholesterol-containing membranes to form pores. Preincubation of the toxin with small amounts of cholesterol inhibits hemolytic activity as well as cytolysis of eucaryotic cells. Members of the group show 40-70% similarity in amino acid sequence, and contain an almost invariant Trp-rich undecapeptide sequence (ECTGLAWEWWR). The TACY are important virulence factors. Recently increased use has been made of molecular methods (PCR, hybridization) in the detection and identification of the TACY producing bacteria.