Surface proteins of Staphylococcus aureus.

Crude cell walls of Staphylococcus aureus of potential immunologic or epidemiologic importance were prepared for study by mechanically disrupting whole cells and applying differential centrifugation. Cell-wall proteins were then released from the wall by lysostaphin digestion and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Distinct electrophoretic protein patterns were found for each of the 12 serologically distinct strains examined. There were two major groups of cell-wall proteins identified in the 45-57-kilodalton (kdal) and 100-190-kdal range, respectively. Proteins in the 45-57-kdal range appeared to represent protein A variants of different apparent molecular mass. Localization experiments with 125I labeling demonstrated the surface location of most of the proteins. These data suggest that selected surface-exposed proteins may be important in defining host immune responses to S. aureus infections.