Open AccessOligomer formation of staphylococcal α‐toxin analyzed by electron microscopy and image processing
Author(s) -
Hebert Hans,
Olofsson Anders,
Thelestam Monica,
Skriver Elisabeth
Publication year - 1992
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1992.tb05880.x
Subject(s) - negative stain , electron microscope , stain , toxin , staining , chemistry , oligomer , biophysics , scanning electron microscope , crystallography , materials science , biochemistry , polymer chemistry , biology , optics , physics , composite material , genetics
The 12S oligomeric form of Staphylococcus aureus α‐toxin has been studied with electron microscopy after incubation of the toxin with membrane preparations or liposomes. The target material originated from human platelet. Different electron microscopic preparation techniques were used including negative staining, freeze‐fracture and vitrification in liquid ethane. Analysis of micrographs with image processing methods revealed two groups of ring‐like structures corresponding to α‐toxin oligomers. One form measured 75 Å in diameter and had a high stain density in the central protein deficient part while the other was larger with a diameter of 100 Å and less stain accumulation in the center. The conditions under which the latter were formed suggest that this corresponds to an inactive loosely‐bound form of the toxin. The high stain density in the smaller particle is consistent with the presence of a penetrating pore in this structure.