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 ae rolysin binds selectively and with high affinity to the glycosylphosph atidylinositol (GPI)-anchored surface protein Thy-1, which is found on T-lymphocyte populations as well as in brain. Less than 1 ng of purif ied Thy-1 could be detected by probing Western blots with the toxin. M utant T-cell lines that lack the ability to add GPI anchors to Thy-1 a nd other surface proteins were much less sensitive to aerolysin, as we re wild-type cells that were pretreated with phosphatidylinositol-spec ific phospholipase C to remove GPI anchored proteins. Phosphatidylchol ine/cholesterol liposomes containing purified Thy-1 in their membranes were much more sensitive to aerolysin than protein-free liposomes.