Initial characterization of the hemolysin stachylysin from Stachybotrys chartarum

Stachybotrys chartarum is a toxigenic fungus that has been associated with human health concerns, including pulmonary hemorrhage and hemosiderosis. Th is fungus produces a hemolysin, stachylysin, which in its apparent monomeri c form has a molecular mass of 11,920 Da as determined by matrix-assisted l aser desorption ionization-time of flight mass spectrometry. However, it ap pears to form polydispersed aggregates, which confounds understanding of th e actual hemolytically active form. Exhaustive dialysis or heat treatment a t 60 degreesC for 30 min inactivated stachylysin. Stachylysin is composed o f about 40% nonpolar amino acids and contains two cysteine residues. Purifi ed stachylysin required more than 6 h to begin lysing sheep erythrocytes, b ut by 48 h, lysis was complete. Stachylysin also formed pores in sheep eryt hrocyte membranes.