1BXT

STREPTOCOCCAL SUPERANTIGEN (SSA) FROM STREPTOCOCCUS PYOGENES

Summary for 1BXT

• Entry DOI: 10.2210/pdb1bxt/pdb
• Descriptor: PROTEIN (STREPTOCOCCAL SUPERANTIGEN) (2 entities in total)
• Functional Keywords: bacterial superantigen, mhc class ii interaction, t cell activation, toxic shock-like syndrome, immune system
• Biological source: Streptococcus pyogenes
• Total number of polymer chains: 2
• Total formula weight: 53908.57

Authors

Sundberg, E.,Jardetzky, T. (deposition date: 1998-10-08, release date: 1998-10-14, Last modification date: 2024-11-20)

Primary citation

Sundberg, E.,Jardetzky, T.S.
Structural basis for HLA-DQ binding by the streptococcal superantigen SSA.
Nat.Struct.Biol., 6:123-129, 1999

PubMed Abstract: Streptococcal superantigen (SSA) is a 28,000 Mr toxin originally isolated from a pathogenic strain of Streptococcus pyogenes that has 60% sequence identity with staphylococcal enterotoxin B (SEB). SSA and SEB, however, do not compete for binding on the surfaces of cells expressing MHC class II molecules. This behavior had been ascribed to SSA and SEB binding to distinct sites on, or different subsets of, HLA-DR molecules. Here we demonstrate that SSA binds predominantly to HLA-DQ, rather than to HLA-DR molecules, and present the crystal structure of SSA at 1.85 A resolution. These data provide a structural basis for interpreting the interaction of SSA with HLA-DQ molecules as well as a foundation for understanding bacterial superantigen affinities for distinct MHC isotypes.

PubMed: 10048922
DOI: 10.1038/5809

Experimental method

X-RAY DIFFRACTION (1.85 Å)