FIG 6 .
An LTA-negative strain has decreased autolytic activity. (A) Autolysis assay. S. aureus strain SA564 and the corresponding clpX, clpP, and clpX ltaSH476Q mutants were analyzed for autolytic activity using a Triton X-100 autolysis assay. (B) Zymogram assay. SA564 and its derived strains were grown to exponential phase, and equal amounts of cell wall-associated proteins were loaded onto an SDS polyacrylamide gel containing heat-killed S. aureus SA564 wild-type cells. Results representative of three independent experiments are shown. The positions of the molecular mass standards are indicated (in kilodaltons) on the left. Atl and Sle1 protein levels were quantified relative to the levels seen with the wild-type strain using ImageJ.