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The projection structure of α-toxin from Staphylococcus aureus in human platelet membranes as analyzed by electron microscopy and image processing

1988; Elsevier BV; Volume: 100; Issue: 2 Linguagem: Inglês

10.1016/0889-1605(88)90026-2

1878-2299

Anders Olofsson, Urban Kavéus, Monica Thelestam, Hans Hebert,

Antimicrobial Resistance in Staphylococcus

Most strains of Staphylococcus aureus produce α-toxin, a 33-kDa membrane active protein which is considered to be an important virulence factor of this bacterium. When α-toxin interacts with membranes an oligomeric form of the toxin can be seen by electron microscopy as characteristic ring structures in the membrane. A two-dimensional study of these annular structures, incorporated in membranes of human platelets, was performed, introducing a partly new method for rotational alignment of individual particles. It is shown that the averaged oligomer consists of six subunits. At neutral pH the outer diameter of the ring is about 75 Å. The stain-filled pore or cavity in the center has a diameter of about 25 Å. The size of the hexamer is increased if the pH is lowered.