What is super antigen and how it works?
What is super antigen and how it works?
Superantigens are bacterial proteins that generate a powerful immune response by binding to Major Histocompatibility Complex class II molecules on antigen-presenting cells and T cell receptors on T cells.
What is the purpose of superantigens?
Superantigens (SAGs) are microbial peptides that can activate the immune system and contribute to autoimmune disorders such as TM. Instead of binding to the highly variable peptide groove of the T-cell receptor as classic antigens do, SAGs interact with the more conserved Vβ region.
What is meant by superantigen?
Superantigens (SAgs) are a class of antigens that result in excessive activation of the immune system. Specifically it causes non-specific activation of T-cells resulting in polyclonal T cell activation and massive cytokine release.
What are examples of superantigens?
Examples of superantigens include toxic shock syndrome toxin-1 (TSST-1), Streptococcal pyrogenic exotoxins (SPE), Staphylococcal enterotoxins (SE), and enterotoxogenic E. coli (ETEC) enterotoxin.
How do AB toxins work?
The AB toxins are two-component protein complexes secreted by a number of pathogenic bacteria. The enzyme component (A) enters the cell through endosomes produced by the oligomeric binding/translocation protein (B), and prevents actin polymerisation through ADP-ribosylation of monomeric G-actin.
What’s the difference between antigens and superantigens?
Antigens are foreign substances (mostly proteins, polysaccharide) or altered self proteins that induces specific immune response. Superantigens are microbial peptides that can polyclonally activate large portion of T cells.
Why some antigens are super antigen?
Superantigens are a class of immunostimulatory molecules produced by bacteria and viruses. Their potent immune effects are due to their unique ability to bind to the major histocompatibility complex (MHC) outside the antigen-binding cleft and to stimulate T cells in a T-cell receptor (TCR) Vbeta-specific manner.
What produces AB toxins?
The enzyme component (A) enters the cell through endosomes produced by the oligomeric binding/translocation protein (B), and prevents actin polymerisation through ADP-ribosylation of monomeric G-actin. Examples of the “A” component of an AB toxin include C….AB toxin.
| Binary_toxB | |
|---|---|
| TCDB | 1.C.42 |
| showAvailable protein structures: |
What are AB type toxins?
Botulinum toxins are members of a broad class of bacterial toxic proteins, called AB toxins. These are secreted bacterial proteins that enter cells and exert their toxic effects by affecting intracellular processes. Other AB toxins include tetanus, cholera, anthrax, shiga and diphtheria toxins.
What are the key features of conventional antigen and superantigen?
Some of the key features of conventional antigen and superantigen is summarized in the table below: Antigens are foreign substances (mostly proteins, polysaccharide) or altered self proteins that induces specific immune response. Superantigens are microbial peptides that can polyclonally activate large portion of T cells.
What are superantigens and how do they work?
Superantigens are microbial peptides that can polyclonally activate large portion of T cells. Superantigens are not processed intracellularly, instead, they bind class II MHC molecules as intact macromolecules and bind outside of the peptide-antigen binding groove.
What happens when superantigens bind to TCR and MHC?
This binding of TCR with MHC-II by superantigen results into polyclonal activation of T cells which can ultimately result in life-threatening autoimmune responses, even deaths. Superantigens bind simultaneously to the Vβ domain of a T-cell receptor and to the α chain of a class II MHC molecule.
What is the difference between superantigens and T dependent antigens?
Superantigens polyclonally activate a large fraction (up to 25%) of the T cells, setting off massive immune response whereas in T dependent antigen only a fraction of (1 in 10^6 -10^4) of the T cell population is able to recognize the antigen and become activated.
