AI Article Synopsis
- The crystal structure of staphylococcal enterotoxin C2 (SEC2) was analyzed, revealing a secondary zinc-binding site near the MHC-binding area, in addition to the previously known primary site.
- New findings show that varying zinc concentrations influence the toxin's activity, with high levels significantly inhibiting T cell responses.
- This suggests that SEC2 interacts with the immune system in different ways depending on zinc levels, highlighting the potential regulatory role of zinc in the toxin's function and T cell interactions.
Article Abstract
The previously determined crystal structure of the superantigen staphylococcal enterotoxin C2 (SEC2) showed binding of a single zinc ion located between the N- and C-terminal domains. Here we present the crystal structure of SEC2 determined to 2.0 A resolution in the presence of additional zinc. The structure revealed the presence of a secondary zinc-binding site close to the major histocompatibility complex (MHC)-binding site of the toxin and some 28 A away from the primary zinc-binding site of the toxin found in previous studies. T cell stimulation assays showed that varying the concentration of zinc ions present affected the activity of the toxin and we observed that high zinc concentrations considerably inhibited T cell responses. This indicates that SEC2 may have multiple modes of interaction with the immune system that are dependent on serum zinc levels. The potential role of the secondary zinc-binding site and that of the primary one in the formation of the TCR.SEC2.MHC complex are considered, and the possibility that zinc may regulate the activity of SEC2 as a toxin facilitating different T cell responses is discussed.
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| http://dx.doi.org/10.1074/jbc.M307333200 | DOI Listing |
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