1HA5

Structural features of a zinc-binding site in the superantigen streptococcal pyrogenic exotoxin A (SpeA1): implications for MHC class II recognition.

Summary for 1HA5

• Entry DOI: 10.2210/pdb1ha5/pdb
• Related: 1B1Z 1FNU 1FNV 1FNW
• Descriptor: STREPTOCOCCAL PYOGENIC EXOTOXIN A1, ZINC ION (3 entities in total)
• Functional Keywords: toxin, molecular recognition, superantigen, exotoxin, zinc binding
• Biological source: STREPTOCOCCUS PYOGENES
• Total number of polymer chains: 4
• Total formula weight: 101767.72

Authors

Baker, M.D.,Gutman, D.M.,Papageorgiou, A.C.,Collins, C.M.,Acharya, K.R. (deposition date: 2001-03-28, release date: 2002-04-03, Last modification date: 2024-11-20)

Primary citation

Baker, M.D.,Gutman, D.M.,Papageorgiou, A.C.,Collins, C.M.,Acharya, K.R.
Structural Features of a Zinc Binding Site in the Superantigen Strepococcal Pyrogenic Exotoxin a (Spea1): Implications for Mhc Class II Recognition.
Protein Sci., 10:1268-, 2001

PubMed Abstract: Streptococcal pyrogenic exotoxin A (SpeA) is produced by Streptococcus pyogenes, and has been associated with severe infections such as scarlet fever and Streptococcal Toxic Shock Syndrome (STSS). In this study, the crystal structure of SpeA1 (the product of speA allele 1) in the presence of 2.5 mM zinc was determined at 2.8 A resolution. The protein crystallizes in the orthorhombic space group P2(1)2(1)2, with four molecules in the crystallographic asymmetric unit. The final structure has a crystallographic R-factor of 21.4% for 7,031 protein atoms, 143 water molecules, and 4 zinc atoms (one zinc atom per molecule). Four protein ligands-Glu 33, Asp 77, His 106, and His 110-form a zinc binding site that is similar to the one observed in a related superantigen, staphylococcoal enterotoxin C2. Mutant toxin forms substituting Ala for each of the zinc binding residues were generated. The affinity of these mutants for zinc ion confirms the composition of this metal binding site. The implications of zinc binding to SpeA1 for MHC class II recognition are explored using a molecular modeling approach. The results indicate that, despite their common overall architecture, superantigens appear to have multiple ways of complex formation with MHC class II molecules.

PubMed: 11369867
DOI: 10.1110/PS.330101

Experimental method

X-RAY DIFFRACTION (2.82 Å)