Influence of Amino Acids on the Synthesis of an Extracellular Proteinase from Staphylococcus aureus

The influence of amino acids on the synthesis of staphylococcal serine-proteinase (proteinase I) by Staphylococcus aureus strain v8 was studied. The repression of proteinase synthesis during the exponential growth phase was not due to any single amino acid in the medium. Proline was essential for proteinase synthesis in post-exponential growth but not for bacterial growth. At low concentrations of glycine, serine, threonine and proline, proteinase synthesis was inhibited, whereas at high concentrations of any of these amino acids, proteinase synthesis was fully induced. During post-exponential growth in the absence of glycine, serine, threonine or proline, the intracellular concentrations of alanine, aspartic acid and glutamic acid increased two to threefold. In the presence of these amino acids, the pool of alanine and aspartic acid remained at a low level and the concentration of glutamic acid decreased. The synthesis of proteinase I is probably repressed at high intracellular concentrations of glutamic acid.