The glycosylphosphatidylinositol-anchored surface glycoprotein Thy-1 is a receptor for the channel-forming toxin aerolysin

Aerolysin is a channel forming protein secreted by virulent Aeromonas spp. Some eucaryotic cells, including T-lymphocytes, are sensitive to very low concentrations of the toxin (<10(-9) M). Here we show that aerolysin binds selectively and with high affinity to the glycosylphosphatidylinositol (GPI)-anchored surface protein Thy-1, which is found on T-lymphocyte populations as well as in brain. Less than 1 ng of purified Thy-1 could be detected by probing Western blots with the toxin. Mutant T-cell lines that lack the ability to add GPI anchors to Thy-1 and other surface proteins were much less sensitive to aerolysin, as were wild-type cells that were pretreated with phosphatidylinositol-specific phospholipase C to remove GPI anchored proteins. Phosphatidylcholine/cholesterol liposomes containing purified Thy-1 in their membranes were much more sensitive to aerolysin than protein-free liposomes.