Effect of Mannitol and Glucose on the Distribution and Trypsin Susceptibility of Protein A of Staphylococcus aureus

Abstract The biological activity and morphological distribution of protein A on the cell surface were studied in a medium containing an excess of either mannitol or glucose, which suppressed protein A production of Staphylococcus aureus , Cowan I strain. Preculture of the organisms in the presence of a sugar suppressed the expression of protein A, resulting in a decrease in the number of cells bound with anti‐ferritin rabbit IgG molecules, which specifically indicate protein A distribution. The distribution pattern of protein A on the cell surface changed with glucose but not with mannitol. The two‐layered ferritin distribution on the organism grown in the control medium was altered into a heavily labeled, thick and rough layer with glucose, suggesting the induction of a conformational change in the polypeptide chain forming protein A. This was positively supported by the increase in trypsin susceptibility of protein A.