Tolaasin Explained

Tolaasin, a toxic secretion by Pseudomonas tolaasii, is the cause of bacterial brown blotch disease of edible mushrooms.^[1] Tolaasin is composed of 18 amino acids, including a beta-hydroxy-octanoic acid chain located at the N terminus.^[2] Tolaasin is a 1985 Da lipodepsipeptide non-host specific toxin. In addition to forming an amphipathic left handed alpha-helix in a hydrophobic environment, the toxin has been shown to form Zn²⁺-sensitive voltage-gated ion channels in planar lipid bilayers and to catalyze erythrocyte lysis by a colloid osmotic mechanism.^[3] At high concentrations, tolaasin acts as a detergent that is able to directly dissolve eukaryotic membranes. The fungal cell membranes are disrupted by the lipopeptides through the formation of trans-membrane pores. Tolaasin pores disrupt the cellular osmotic pressure, leading to membrane collapse. Compounds that inhibit the toxicity of tolaasin have been identified from varying food additives. Tolaasin cytotoxicity can be effectively inhibited by food detergents, as well as sucrose and polyglycerol esters of fatty acids.^[4]

Notes and References

1. Physiol. Molec. Pl. Pathol. 42. 6. 1993 . 373–384 . Evidence for the involvement of the surface active properties of the extracellular toxin tolaasin in the manifestation of brown blotch disease symptoms by Pseudomonas tolaasii on Agaricus bisporus . Hutchison, M. L. . Johnstone, K. J. . 10.1016/S0885-5765(05)80013-X.
2. Scherlach . Kirstin . Lackner . Gerald . Graupner . Katharina . Pidot . Sacha . Bretschneider . Tom . Hertweck . Christian . 2013-12-16 . Biosynthesis and Mass Spectrometric Imaging of Tolaasin, the Virulence Factor of Brown Blotch Mushroom Disease . ChemBioChem . en . 14 . 18 . 2439–2443 . 10.1002/cbic.201300553 . 24222604 . 43528692 . 1439-4227.
3. Physiol. Molec. Pl. Pathol. 39. 1. 1991 . 57–70 . Biological properties and spectrum of activity of tolaasin, a lipodepsipeptide toxin produced by the mushroom pathogen Pseudomonas tolaasii. on Agaricus bisporus . Rainey, P. B. . Brodey, C. L. . Johnstone, K. J. . 10.1016/0885-5765(91)90031-C.
4. Yun . Yeong-Bae . Cho . Kwang-Hyun . Kim . Young-Kee . January 2023 . Inhibition of Tolaasin Cytotoxicity Causing Brown Blotch Disease in Cultivated Mushrooms Using Tolaasin Inhibitory Factors . Toxins . en . 15 . 1 . 66 . 10.3390/toxins15010066 . 36668885 . 9867037 . 2072-6651 . free .