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Determination of biologically active region in toxic shock syndrome toxin 1
N P Kokan-Moore1, M S Bergdoll
1Department of Food Microbiology and Toxicology, University of Wisconsin-Madison.
Abstract:
The biologically active areas of toxic shock syndrome toxin 1 (TSST-1) were investigated using chemical fragmentation of the toxin with cyanogen bromide (CNBr). All three main CNBr-generated fragments of TSST-1, with estimated molecular weights of 20,000, 18,000, and 15,000, reacted with monoclonal antibodies (MAbs) 4T, 5T, 6T, 7T, 8T, and 9T, as determined by autoradiography. The epitopes involved in the mitogenic active site were located on the 15,000-Da internal fragment as determined by the neutralization of the mitogenic activity by the MAb. Modification of the methionine residues in the native TSST-1 by alkylation with iodoacetic acid had no effect on the serologic or mitogenic activity.
Insights
Researchers identified the biologically active regions of toxic shock syndrome toxin 1 (TSST-1) using chemical fragmentation. The study pinpointed the mitogenic active site to an internal fragment, crucial for understanding TSST-1
Area of Science:
- Microbiology
- Immunology
- Protein Chemistry
Background:
- Toxic Shock Syndrome Toxin 1 (TSST-1) is a key virulence factor in Staphylococcus aureus infections.
- Understanding the toxin's structure-activity relationship is crucial for developing targeted therapies and diagnostics.
Purpose of the Study:
- To delineate the biologically active regions of TSST-1.
- To identify the specific fragment responsible for the toxin's mitogenic activity.
- To investigate the role of methionine residues in TSST-1's function.
Main Methods:
- Chemical fragmentation of TSST-1 using cyanogen bromide (CNBr).
- Analysis of fragments using monoclonal antibodies (MAbs) and autoradiography.
- Assessment of mitogenic activity neutralization by MAbs.
- Chemical modification of methionine residues via alkylation.
Main Results:
- Three major CNBr fragments (20,000, 18,000, and 15,000 Da) were generated and reacted with multiple MAbs.
- The 15,000-Da internal fragment was identified as containing the epitopes for the mitogenic active site.
- Alkylation of methionine residues did not affect the serologic or mitogenic activity of TSST-1.
Conclusions:
- The mitogenic activity of TSST-1 is localized to a specific internal fragment.
- This fragment contains critical epitopes recognized by specific MAbs.
- Methionine residues are not essential for the serologic or mitogenic functions of TSST-1.