Two Adjacent Residues in Staphylococcal Enteromxlns

The T cell receptor (TCR) V/3-determining region of two bacterial superantigens, staphylococcal enterotoxin A (SEA) and SEE, has been mapped to the COOH-terminal region of SEA and SEE using a panel of recombinant SEA/SEE hybrids. Total TCR V/3 mRNA enrichment in human peripheral blood T cell cultures was determined by a novel single-tube amplification technique using a redundant V/3-spedfic primer. SEA routinely enriched mRNA coding for hV/31.1, 5.3, 6.3, 6.4, 6.9, 7.3, 7.4, and 9.1, while SEE, which is 83% homologous to SEA, enriched hV/~5.1, 6.3, 6.4, 6.9, and 8.1 mRNA. Exchanging residues 206 and 207 was sufficient to convert in toto the TCR V/3 response of human peripheral T lymphocytes. In addition, an SEA-reactive routine T cell line, SO3 (mV/~17), unresponsive to wild-type SEE responded to SEE-S2~176 while an SEE-specific human T cell line, Jurkat (hV/38.1), unresponsive to SEA was stimulated strongly by SEA-p2~ 2~ Exchanging all other regions of SEA and SEE except residues 206 and 207 did little to change the V/3 response. Thus, the V/~ binding region appears to be a stable, discrete domain localized within the COOH-terminal region that is largely unaffected by the considerable amino add variability between SEA and SEE. This region may interact directly with TCR V/g