Crystal structure of staphylococcal enterotoxin G (SEG) in complex with mouse T-cell receptor β chain.

FERNANDEZ MM, CHO S, DEMARZI MC, KERZIC MC, ROBINSON H, MARIUZZA RA, MALCHIODI EL.

JOURNAL OF BIOLOGICAL CHEMISTRY

AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Lugar: Washington; Año: 2011 vol. 286 p. 1189 - 1195

0021-9258

Superantigens (SAgs) are bacterial or viral toxins that bind major histocompatibility complex class II (MHC-II) molecules and T-cell receptor (TCR) in a non-conventional manner, inducing T-cell activation that leads to inflammatory cytokine production which may result in acute toxic shock. In addition, the emerging threat of purpura fulminans and community-associated meticillin-resistant Staphylococcus aureus emphasizes the importance of a better characterization of SAg binding to their natural ligands that may allow the development of reagents to neutralize their action. The three-dimensional structure of the complex between a mouse TCR β chain (mVβ8.2) and staphylococcal enterotoxin G (SEG) at 2.0 Å resolution revealed a binding site which does not conserve the ?hot spots? present in mVβ8.2-SEC2, mVβ8.2-SEC3, mVβ8.2-SEB and mVβ8.2-SPEA complexes. Analysis of the mVβ8.2-SEG interface allowed us to explain the higher affinity of this complex compared with the others, which may account for the early activation of T-cells bearing mVβ8.2 by SEG. This mode of interaction between SEG and mVβ8.2 could be an adaptive advantage to bestow on the pathogen a faster rate of colonization of the host.