Figure 3.

Proposed model for the mechanism of E-mediated cell lysis. The E protein is synthesized in the cytoplasm and integrated into the inner membrane. The cytoplasmic SlyD PPIase is required for E protein accumulation, either before or after E reaches the membrane. We propose that as E accumulates in the membrane it interacts with and inhibits MraY. Inhibition of MraY activity would result in the inhibition of cell wall synthesis and cell lysis. The predicted topology of MraY in the membrane is drawn with the positions of the mutations affecting lysis indicated with an x. The topology of the E protein is drawn according to the observation that the C terminus is located in the cytoplasm (R.Y., unpublished data), although it is not known whether the N terminus of E actually traverses the membrane.