Details

Autor(en) / Beteiligte

• Cavallin, Anders
• Arozenius, Helena
• Kristensson, Karin
• Antonsson, Per
• Otzen, Daniel E.
• Björk, Per
• Forsberg, Göran

Titel

The Spectral and Thermodynamic Properties of Staphylococcal Enterotoxin A, E, and Variants Suggest That Structural Modifications Are Important to Control Their Function

Ist Teil von

• The Journal of biological chemistry, 2000-01, Vol.275 (3), p.1665-1672

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2000

Link zum Volltext

Quelle

Elektronische Zeitschriftenbibliothek (Open access)

Beschreibungen/Notizen

• The superantigens staphylococcal enterotoxin A and E (SEA and SEE) can activate a large number of T-cells. SEA and SEE have approximately 80% sequence identity but show some differences in their biological function. Here, the two superantigens and analogues were characterized biophysically. SEE was shown to have a substantially higher thermal stability than SEA. Both SEA and SEE were thermally stabilized by 0.1 mm Zn2+ compared with Zn2+-reduced conditions achieved using 1 mmEDTA or specific replacements that affect Zn2+coordination. The higher stability of SEE was only partly caused by the T-cell receptor (TCR) binding regions, whereas regions in the vicinity of the major histocompatibility complex class II binding sites affected the stability to a greater extent. SEE exhibited a biphasic denaturation between pH 5.0–6.5, influenced by residues in the TCR binding regions. Interestingly, enzyme-linked immunosorbent assay, isoelectric focusing, and circular dichroism analysis indicated that conformational changes had occurred in the SEA/E chimerical constructs relative to SEA and SEE. Thus, it is proposed that the Zn2+binding site is very important for the stability and potency of SEA and SEE, whereas residues in the TCR binding site have a substantial influence on the molecular conformation to control specificity and function.