Haemolysin-derived synthetic peptides with pore-forming and haemolytic activity

Escherichia coli haemolysin (Hlya) is a pore-forming protein which belongs to the family of 'Repeat-toxins' (RTX) (Lo et al., 1987; Lally et al., 1989; Kraig et al., 1990). A model for the pore-forming structure of HlyA has been proposed (Ludwig et al., 1991) which consists of eight transmembrane segments all present in this hydrophobic region of HlyA. We report here that two synthetic peptides of 10 and 8 amino acids in length (Pep1 and Pep2, respectively), which are derived from transmembrane segment V, are able to form pores in an artificial lipid bilayer. In addition, Pep1 exhibits strong haemolytic activity when tested on human red blood cells (HRBCs). The haemolytic activity of Pep1 and of E. coli haemolysin is completely inhibited by antibodies raised against Pep1.