Staphylococcal/Streptococcal toxin, OB-fold (IPR006173)

Short name: Staph_tox_OB

Overlapping homologous superfamilies

Domain relationships



Staphylococcus aureus is a Gram-positive coccus that grows in clusters or pairs, and is the major cause of nosocomial infections due to its multiple antibiotic resistant nature [PMID: 3782090]. Patients who are immunocompromised (e.g., those suffering from third degree burns or chronic illness) are at risk from deep staphylococcal infections, such as osteomyelitis and pneumonia. Most skin infections are also caused by this bacterium.

Many virulence mechanisms are employed by Staphylococci to induce pathogenesis: these can include polysaccharide capsules and exotoxins [PMID: 3782090]. One of the major virulence exotoxins is toxic shock syndrome toxin (TSST), which is secreted by the organism upon successful invasion. It causes a major inflammatory response in the host via superantigenic properties, and is the causative agent of toxic shock syndrome.

The structure of the TSST protein was originally determined to 2.5A by means of X-ray crystallography [PMID: 8107781]. The N- and C-terminal domains both contain regions involved in MHC class II association; the C-terminal domain is also implicated in binding the T-cell receptor. Overall, the structure resembles that of Staphylococcal enterotoxin B (SEB), but differs in its N terminus and in the degree to which a long central helix is covered by surface loops [PMID: 8268150]. The region around the carboxyl end of this helix is proposed to govern the superantigenic properties of TSST. An adjacent region along this helix is thought to be critical in the ability of TSST to induce toxic shock syndrome. Most recently, the structures of five mutants of TSST have been determined to 1.95A [PMID: 9194182]. The mutations are in the central alpha-helix, and allow mapping of portions of TSST involved in superantigenicity and lethality.

GO terms

Biological Process

GO:0009405 pathogenesis

Molecular Function

No terms assigned in this category.

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.