Alteration of human erythrocyte plasma membranes by perfringolysin O as revealed by freeze-fracture electron microscopy. Studies on Clostridium perfringens exotoxins V.
When human erythrocyte membranes were treated with perfringolysin O (Clostridium perfringens theta-toxin) and examined by electron microscopy after freeze-fracture, two ultrastructural alterations were observed in fracture faces of membrane. (1) A random aggregation of intramembranous particles was seen in the fracture face of the protoplasmic half (PF face) of all membranes treated with the toxin, even if at a low concentration (40 hemolytic units/ml). On the other hand, the aggregation in the fracture face of the exoplasmic half (EF face) was observed only in membranes treated with a high concentration (3300 hemolytic units/ml) for 2 h. (2) Round protrusions and "cavities" with 30 nm in diameter were visible in EF and PF faces of membranes treated with a high concentration, respectively. These structures were always protruded toward cytoplasmic side, but did not appear to form holes through the membrane. Ring and arc shaped structures with a dark center of 26 nm and a distinct border of 5 nm in width were observed when the toxin alone was negatively stained at a very high concentration (170,000 hemolytic units/ml). These structures were also produced in the presence of cholesterol even if the toxin concentration was low.
D001427:Bacterial Toxins / Q000494:pharmacology*; D003016:Clostridium perfringens; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000648:ultrastructure*; D004912:Erythrocytes / Q000648:ultrastructure*; D005614:Freeze Fracturing; D006460:Hemolysin Proteins; D008854:Microscopy, Electron
D001427:Bacterial Toxins; D006460:Hemolysin Proteins; C020452:Clostridium perfringens theta-toxin