EXPRESSION AND PURIFICATION OF RECOMBINANT TOXIC-SHOCK-SYNDROME TOXIN-I

Toxic-shock-syndrome toxin I (TSSTI), an exotoxin produced by certain strains of Staphylococcus aureus, has been closely associated with the pathogenesis of toxic shock syndrome. Outside the context of its stap hylococcal host, TSSTI may offer therapeutic uses. We report here a st rategy for high-level expression and simplified purification of TSSTI. We have subcloned the coding region for TSSTI into a vector containin g an inducible T7 promoter sequence and expressed the protein in an Es cherichia coli host strain. The recombinant TSSTI protein contained te n sequential histidine residues (Histag) at its N-terminus, which enab led its efficient purification using nickel-agarose-affinity resin. Hi stag-TSSTI (H-TSSTI) was further purified to homogeneity using, a size -exclusion column. By this system, 80 mg of highly purified H-TSSTI ca n be consistently obtained per litre of culture in under 3 days. H-TSS TI retained biological activity and was unaffected by the presence of the Histag, as measured in lymphocyte proliferation assays.