Related Experiment Videos
Oligomer formation of staphylococcal alpha-toxin analyzed by electron microscopy and image processing
H Hebert1, A Olofsson, M Thelestam
1Center for Structural Biochemistry, Karolinska Institutet, NOVUM, Huddinge, Sweden.
FEMS Microbiology Immunology
|September 1, 1992
Summary
Electron microscopy revealed two forms of Staphylococcus aureus alpha-toxin oligomers. One form, a 75 A pore, suggests a functional toxin, while a larger 100 A form indicates an inactive state.
Area of Science:
- Microbiology
- Structural Biology
- Biophysics
Background:
- Staphylococcus aureus alpha-toxin is a major virulence factor.
- Understanding its oligomeric forms is crucial for elucidating its mechanism of action.
Purpose of the Study:
- To characterize the oligomeric structures of Staphylococcus aureus alpha-toxin.
- To differentiate between active and inactive toxin forms using electron microscopy.
Main Methods:
- Incubation of alpha-toxin with human platelet membrane preparations and liposomes.
- Application of various electron microscopy techniques: negative staining, freeze-fracture, and vitrification.
- Image processing analysis of micrographs.
Main Results:
- Identification of two distinct ring-like alpha-toxin oligomers.
- A smaller 75 A diameter form with high central stain density, indicative of a pore.
- A larger 100 A diameter form with less central stain, suggesting a loosely-bound, inactive state.
Conclusions:
- The study successfully visualized two oligomeric forms of Staphylococcus aureus alpha-toxin.
- The findings suggest a structural basis for distinguishing between active pore-forming and inactive toxin states.