Production
TSST-1 is a protein encoded by the tstH gene, which is part of the mobile genetic element staphylococcal pathogenicity island 1. The toxin is produced in the greatest volumes during the post-exponential phase of growth, which is similar among pyrogenic toxin superantigens, also known as PTSAgs. Oxygen is required in order to produce TSST-1, in addition to the presence of animal protein, low levels of glucose, and temperatures between 37-40°C (98.6-104°F). Production is optimal at pH's close to neutral and when magnesium levels are low, and is further amplified by high concentrations of S. aureus, which indicates its importance in establishing infection.
TSST-1 differs from other PTSAgs in that its genetic sequence does not have a homolog with other superantigen sequences. TSST-1 does not have a cysteine loop, which is an important structure in other PTSAgs, and in fact it does not have any cysteine residues at all. TSST-1 is also different from other PTSAgs in its ability to cross mucus membranes, which is why it is an important factor in menstrual TSS When the protein is translated, it is in a pro-protein form, and can only leave the cell once the signal sequence has been cleaved off. The explagr locus is one of the key sites of positive regulation for many of the S. aureus genes, including TSST-1. Additionally, alterations in the expression of the genes ssrB and srrAB have an impact on the transcription of TSST-1. Further, high levels of glucose inhibit transcription, since glucose acts as a catabolite repressor.
Read more about this topic: Toxic Shock Syndrome Toxin
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