Bioactivity and mechanism of action of Lophozozymus pictor toxin

Abstract

The bioactivity of Lophozozymus pictor toxin (LPTX) and the possible mechanism of action of the purified toxin are described. LPTX is found to possess palytoxin-like bioactivities. Besides exhibiting cytotoxic and haemolytic properties, LPTX causes the release of K+ from erythrocytes and inhibits 2-[14C]deoxy-d-glucose uptake into HeLa cells. Although LPTX acts on HeLa cell and erythrocyte membranes, it does not interact with mitochondrial or liposomal membranes containing different phospholipid compositions. Ouabain, but not sphingomyelin, is able to prevent the toxic effects of LPTX. This antagonistic effect of ouabain on LFTX suggests that the toxin might mediate its toxic effects via the membrane Na+/K+-ATPase but not through interaction with membrane lipids.