RESUMO
AIM: Determine protein specter that Staphylococcus aureus synthesizes and secretes at early growth phase--the exponential phase. MATERIALS AND METHODS: Proteins secreted by S. aureus strain 6 into cultivation medium at the end of exponential growth phase (4.5 hours) were studied. 11 proteins were identified by liquid chromatography--mass-spectrometry method. RESULTS: Only in 3 of these proteins the presence of signal peptides was predicted, which indicates their extracellular localization; the rest of the proteins were localized predominantly in bacterial cytoplasm. 5 of 11 proteins function as enzymes of carbohydrate metabolism. Other extracellular proteins that could indicate its contamination with proteins from disrupted bacterial cells were not detected in S. aureus cultural liquid filtrate. It has been suggested that enzymes of carbohydrate metabolism can provide bacterial cells with energy necessary for passage from lag-phase into exponential growth phase. Superoxide dismutase enzyme probably provides the course of oxidation-reduction processes. Synthesis of other proteolytic enzymes and toxins is carried out at later stages of development of bacterial population. Immunization of mice with a mixture of 11 identified proteins showed their protective properties after infection by S. aureus 6 strain. CONCLUSION: Based on the above-mentioned, the complex of isolated proteins may be perspective in development of a new strategy of prophylaxis and therapy of staphylococcus infections.
