TSST-1

Toxic shock syndrome toxin (TSST) is a superantigen with a size of 22 kDa produced by 5 to 25% of Staphylococcus aureus isolates. It causes toxic shock syndrome (TSS) by stimulating the release of large amounts of interleukin-1, interleukin-2 and tumour necrosis factor. In general, the toxin is not produced by bacteria growing in the blood; rather, it is produced at the local site of an infection, and then enters the blood stream.

Toxic shock syndrome toxin 1 (TSST-1), a prototype superantigen secreted by a Staphylococcus aureus bacterium strain in susceptible hosts, acts on the vascular system by causing inflammation, fever, and shock. This bacterium strain that produces the TSST-1's can be found in any area of the body, but live mostly in the vagina of infected women. TSST-1 is a bacterial exotoxin found in patients who have developed toxic shock syndrome (TSS), which can be found in menstruating women or any man or child for that matter. One-third of all TSS cases have been found in men. This statistic could possibly be due to surgical wounds or any skin wound. TSST-1 is the cause of 50% of non-menstrual and 100% of all menstrual TSS cases.

In the nucleotide sequence of TSST-1, there is a 708 base-pair open-reading frame and a Shine-Dalgarno sequence which is seven base pairs downstream from the start site. In the entire nucleotide sequence, only 40 amino acids make up the signal peptide. A single signal peptide consists of a 1 to 3 basic amino acid terminus, a hydrophobic region of 15 residues, a proline (Pro) orglycine (Gly) in the hydrophobic core region, a serine (Ser) or threonine (Thr) amino acid near the carboxyl terminal end of the hydrophobic core, and an alanine (Ala) or glycine (Gly) at the cleavage site. A mature TSST-1 protein has a coding sequence of 585 base pairs. The entire nucleotide sequence was determined by Blomster-Hautamaazg, et al., as well as by other researchers with other experiments. Consisting of a single polypeptide chain, the structure of holotoxin TSST-1 is three-dimensional and consists of an alpha (α) and beta (β) domain. This three-dimensional structure of the TSST-1 protein was determined by purifying the crystals of the protein. The two domains are adjacent from each other and possess unique qualities. Domain A, the larger of the two domains, contains residues 1-17 and 90-194 in TSST-1 and consists of a long alpha (α) helix with residues 125-140 surrounded by a 5-strand beta (β) sheet. Domain B is unique because it contains residues 18-89 in TSST-1 and consists of a (β) barrel made up of 5 β-strands.Crystallography methods show that the internal β-barrel of domain B contains several hydrophobic amino acids and hydrophilic residues on the surface of the domain, which allows TSST-1 to cross mucous surfaces of epithelial cells. Even though TSST-1 consists of several hydrophobic amino acids, this protein is highly soluble in water. TSST-1 is resistant to heat and proteolysis. It has been shown that TSST-1 can be boiled for more than an hour without any presence of denaturation or direct effect on its function.

...
Wikipedia