title: Regulation of staphylococcal toxic shock syndrome toxin-1 and total exoprotein production by magnesium ion.
abstract: The effect of Mg2+ on in vitro production of extracellular proteins and, specifically, of toxic shock syndrome toxin-1 (TSST-1), by Staphylococcus aureus in a chemically defined medium was examined. As previously observed, the organisms did not proliferate in the absence of divalent cations. Low levels of Mg2+ (0.02 to 0.04 mM) permitted submaximal proliferation and elevated production of exoproteins. When the Mg2+ concentration was raised to 0.4 mM, multiplication was optimal and exoprotein levels were depressed. Ca2+ and Mn2+ diminished the effect of limiting Mg2+. The increased levels of exoproteins were not due to cell lysis or leakage since intracellular TSST-1 levels were not high enough to account for the increase in extracellular TSST-1 and since the intracellular enzyme, lactate dehydrogenase, was not found in culture supernatants. Cells cultured in low levels of Mg2+ remained in logarithmic growth longer than did those cultured in high concentrations of Mg2+ and, unlike the latter, produced exoproteins throughout the logarithmic growth phase. Low Mg2+ had no effect on cultures in the stationary phase, and organisms cultured in low Mg2+ recovered fully when transferred to high Mg2+. We conclude that, when cultured in medium deficient in Mg2+, S. aureus responds early in the growth cycle by increasing production of many extracellular proteins, including TSST-1.
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis*; D001427:Bacterial Toxins; D002118:Calcium / Q000494:pharmacology; D002455:Cell Division; D003470:Culture Media; D004305:Dose-Response Relationship, Drug; D004768:Enterotoxins / Q000096:biosynthesis*; D007501:Iron / Q000494:pharmacology; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D008345:Manganese / Q000494:pharmacology; D010447:Peptide Hydrolases / Q000032:analysis; D013211:Staphylococcus aureus / Q000166:cytology / Q000378:metabolism*; D018089:Superantigens
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003470:Culture Media; D004768:Enterotoxins; D018089:Superantigens; C030107:enterotoxin F, Staphylococcal; D008345:Manganese; D007501:Iron; D010447:Peptide Hydrolases; D008274:Magnesium; D002118:Calcium