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Publication Abstract from PubMed

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.

Identification of a secondary zinc-binding site in staphylococcal enterotoxin C2. Implications for superantigen recognition.,Papageorgiou AC, Baker MD, McLeod JD, Goda SK, Manzotti CN, Sansom DM, Tranter HS, Acharya KR J Biol Chem. 2004 Jan 9;279(2):1297-303. Epub 2003 Oct 14. PMID:14559915^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.