FIGURE 3.

c-di-AMP overproduction in S. aureus strain LAC*. A, growth of S. aureus strains LAC* and LAC*ΔgdpP. Cultures were diluted to an A₆₀₀ of 0.05 and grown to exponential phase prior to dilution to an A₆₀₀ of 0.05 and growth for 8 h. The average A₆₀₀ readings and standard deviations of three independent experiments are plotted. B, intracellular c-di-AMP levels. The concentration of c-di-AMP in the cytoplasm of LAC* and LAC*ΔgdpP was determined by LC-MS/MS and plotted as described in Fig. 1C. C, TEM images of wild type LAC* and LAC*ΔgdpP S. aureus strains. Samples were taken at the 4-h time point during bacterial growth and prepared for TEM as described under “Experimental Procedures.” Representative images and scale bars are shown. White arrows indicate extramembranous material visible in the gdpP mutant strain.