PDBsum entry 1uup

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Toxin PDB id
Protein chains
221 a.a. *
_ZN ×4
Waters ×136
* Residue conservation analysis
PDB id:
Name: Toxin
Title: Crystal structure of a dimeric form of streptococcal pyrogenic exotoxin a (spea1).
Structure: Exotoxin type a. Chain: a, b, c, d. Fragment: residues 31-251. Synonym: streptococcal pyogenic exotoxin a1, spe a, scarlet fever toxin, erythrogenic toxin. Engineered: yes
Source: Streptococcus pyogenes. Organism_taxid: 1314. Strain: bl21. Expressed in: escherichia coli. Expression_system_taxid: 511693.
2.6Å     R-factor:   0.215     R-free:   0.282
Authors: M.D.Baker,I.Gendlina,C.M.Collins,K.R.Acharya
Key ref:
M.D.Baker et al. (2004). Crystal structure of a dimeric form of streptococcal pyrogenic exotoxin A (SpeA1). Protein Sci, 13, 2285-2290. PubMed id: 15295110 DOI: 10.1110/ps.04826804
08-Jan-04     Release date:   12-Aug-04    
Go to PROCHECK summary

Protein chains
P0DJY7  (SPEA_STRPY) -  Exotoxin type A
250 a.a.
221 a.a.*
Key:    Secondary structure  CATH domain
* PDB and UniProt seqs differ at 31 residue positions (black crosses)

 Gene Ontology (GO) functional annotation 
  GO annot!
  Cellular component     extracellular region   1 term 
  Biological process     pathogenesis   1 term 


DOI no: 10.1110/ps.04826804 Protein Sci 13:2285-2290 (2004)
PubMed id: 15295110  
Crystal structure of a dimeric form of streptococcal pyrogenic exotoxin A (SpeA1).
M.D.Baker, I.Gendlina, C.M.Collins, K.R.Acharya.
Streptococcal pyrogenic exotoxin A (SpeA1) is a bacterial superantigen associated with scarlet fever and streptococcal toxic shock syndrome (STSS). SpeA1 is found in both monomeric and dimeric forms, and previous work suggested that the dimer results from an intermolecular disulfide bond between the cysteines at positions 90 of each monomer. Here, we present the crystal structure of the dimeric form of SpeA1. The toxin crystallizes in the orthorhombic space group P212121, with two dimers in the crystallographic asymmetric unit. The final structure has a crystallographic R-factor of 21.52% for 7248 protein atoms, 136 water molecules, and 4 zinc atoms (one zinc atom per molecule). The implications of SpeA1 dimer on MHC class II and T-cell receptor recognition are discussed.
  Selected figure(s)  
Figure 1.
Figure 1. (A) The crystal structure of native SpeA1; the arrangement of the four molecules in the crystallographic asymmetric unit. Inter- and intramolecular disulfide bonds are shown in ball-and-stick representation. (B^) 2F[o] - F[c] electron density map contoured at 1 clearly shows the density for the intermolecular disulfide bond. (C) C trace of molecule 1 from both native (red) and dimeric (green) SpeA1 indicating movement of the disulfide loop. N and C termini are labeled; C of Cys 90 is shown as a colored ball. (D) Cartoon representation of SpeA1 dimer possible interactions. The location of the T-cell receptor binding sites (T) in the dimer prevents interaction with TCRs if SpeA1 dimer binds to MHC class II molecules via its zinc site. The location of the generic MHC class II binding sites (G) means that they are unable to interact with MHC II molecules.
  The above figure is reprinted by permission from the Protein Society: Protein Sci (2004, 13, 2285-2290) copyright 2004.