Regulation of toxic shock syndrome toxin-1 gene in Staphylococcus aureus.

Staphylococcus aureus produces various proteins in response to discrete signals from the external environment like many other pathogenic microorganisms. Certain staphylococcal exoproteins including toxic shock syndrome toxin-1 (TSST-1) are secreted according to the stimuli from the environment, and the quantity synthesized is influenced by a number of different parameters. Using a transposon Tn551-mediated mutagenesis, a mutant (RN 6390) defective in TSST-1 from synthesis was constructed. TSST-1 from wild strain and mutant stain were purified and quantitated from culture supernatants of Staphylococcus aureus. The mutant strain RN 6390 produced only 2% of TSST-1 compared with that produced by the wild strain RN4282. Southern blot hybridization with a tst (TSST-1 gene) probe indicated that the inactivated chromosomal locus is distinct from the tst. These results suggest that transposition by Tn551 inactivated a chromosomal locus whose activity was essential for the expression of the TSST-1 gene.