Formation of extracellular protein A by Staphylococcus aureus.

Staphylococcus aureus contains cell wall protein A as well as extracellular protein A. The two types of protein A have very similar amino acid compositions, electrophoretic mobilities and sizes. 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 the ribosomes. Bacteria in the stationary phase, however, release protein A as a result of cell lysis. Protoplasts have been isolated which produce protein A as extensively as the intact bacteria but because of the absence of of the formation of extracellular protein A is observed from cells also producing cell wall protein A.