The structural basis of T cell activation by superantigens.

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TitleThe structural basis of T cell activation by superantigens.
Publication TypeJournal Article
Year of Publication1999
AuthorsLi, H, Llera, A, Malchiodi, EL, Mariuzza, RA
JournalAnnu Rev Immunol
Date Published1999
KeywordsAmino Acid Sequence, Animals, Autoimmune Diseases, Foodborne Diseases, Histocompatibility Antigens Class II, Humans, Immunotherapy, Kinetics, Lymphocyte Activation, Macromolecular Substances, Models, Molecular, Molecular Sequence Data, Protein Conformation, Receptors, Antigen, T-Cell, alpha-beta, Shock, Septic, Superantigens, T-Lymphocytes

Superantigens (SAGs) are a class of immunostimulatory and disease-causing proteins of bacterial or viral origin with the ability to activate large fractions (5-20%) of the T cell population. Activation requires simultaneous interaction of the SAG with the V beta domain of the T cell receptor (TCR) and with major histocompatibility complex (MHC) class II molecules on the surface of an antigen-presenting cell. Recent advances in knowledge of the three-dimensional structure of bacterial SAGs, and of their complexes with MHC class II molecules and the TCR beta chain, provide a framework for understanding the molecular basis of T cell activation by these potent mitogens. These structures along with those of TCR-peptide/MHC complexes reveal how SAGs circumvent the normal mechanism for T cell activation by peptide/MHC and how they stimulate T cells expressing TCR beta chains from a number of different families, resulting in polyclonal T cell activation. The crystal structures also provide insights into the basis for the specificity of different SAGs for particular TCR beta chains, and for the observed influence of the TCR alpha chain on SAG reactivity. These studies open the way to the design of SAG variants with altered binding properties for TCR and MHC for use as tools in dissecting structure-activity relationships in this system.

Alternate JournalAnnu. Rev. Immunol.
PubMed ID10358765
Grant ListAI36900 / AI / NIAID NIH HHS / United States
AI42937 / AI / NIAID NIH HHS / United States