Candidalysin is a cytolytic 31-amino acid α-helical peptide toxin found in the opportunistic pathogen Candida albicans. As such, Candidalysin is a rare fungal example of a classical virulence factor. Hyphal morphogenesis in C. albicans is associated with damage to host epithelial cells; during this process Candidalysin is released.
C. albicans produces the protein Ece1 (extent of cell elongation 1) during the formation of hyphae. Cleavage of Ece1 at arginine/lysine residues by Kex2 and Kex1 releases several peptides, including the toxin Candidalysin. Consequently, Candidalysin is also known as Ece1-III62–92K. C. albicans strains missing Candidalysin do not damage epithelial cells and are said to be avirulent with respect to mucosal infections. The toxin is also responsible for the activation and propagation of a cellular immune response.