Research Notes Bacterial Blotch Disease of the Cultivated Mushroom Is Caused by an Ion Channel Forming Lipodepsipeptide Toxin

Abstract

Tolaasin, a lipodepsipeptide toxin produced by the mushroom pathogen Pseudomonas tolaasii was shown to form voltage-dependent, cation-selective, ion channels in planar lipid bilayers. Tolaasin-induced ion channels were inhibited by the addition of Zn2+, which also inhibited the activity of tolaasin on horse erythrocytes and mushroom tissue. Tolassin-144, an altered form of tolaasin lacking three consecutive D-amino acids from the alpha-helical portion of the molecule, did not form ion channels in plannar lipid bilayers, did not lyse erythrocytes, and showed reduced ability to cause disease symptoms on mushroom tissue.