1BXT

STREPTOCOCCAL SUPERANTIGEN (SSA) FROM STREPTOCOCCUS PYOGENES


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.85 Å
  • R-Value Free: 0.263 
  • R-Value Work: 0.237 
  • R-Value Observed: 0.237 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Structural basis for HLA-DQ binding by the streptococcal superantigen SSA.

Sundberg, E.Jardetzky, T.S.

(1999) Nat Struct Biol 6: 123-129

  • DOI: 10.1038/5809
  • Primary Citation of Related Structures:  
    1BXT

  • 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 t ...

    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.


    Organizational Affiliation

    Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
PROTEIN (STREPTOCOCCAL SUPERANTIGEN)AB234Streptococcus pyogenesMutation(s): 0 
Gene Names: SSA
Find proteins for Q54971 (Streptococcus pyogenes)
Explore Q54971 
Go to UniProtKB:  Q54971
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.85 Å
  • R-Value Free: 0.263 
  • R-Value Work: 0.237 
  • R-Value Observed: 0.237 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 81.9α = 90
b = 84.55β = 90
c = 144.01γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
AMoREphasing
X-PLORrefinement

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1998-10-14
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance