FORMATION OF EXTRACELLULAR PROTEIN-A BY STAPHYLOCOCCUS-AUREUS

S. aureus contains cell wall protein A and extracellular protein A. The 2 types of protein A have very similar amino acid composition, electrophoretic mobility and size. The release of extracellular protein A from exponentially growing bacteria is dependent on protein synthesis de novo and protein A is released directly after being synthesized on ribosomes. Bacteria in the stationary phase release protein A due to cell lysis. Protoplasts were isolated which produce protein A as extensively as the intact bacteria but due to the absence of cell wall all the protein A is of extracellular type. In the presence of puromycin, an enhancement of the formation of extracellular protein A is observed from cells also producing cell wall protein A.