Fig. 1.

Domain structure of FtsEX and EnvC. (A) Diagram of the FtsEX ABC system. FtsX (X) is the TMD component, and FtsE (E) is the ATPase component (15). The complex is in the inner membrane (IM) with FtsE located on the cytoplasmic face of the membrane. (B) Membrane topology of FtsX as determined by Weiss and coworkers (20). The loop1 domain is composed of residues 93–223. Membrane orientation is the same as in A. (C) Domain structure of EnvC. EnvC is a periplasmic protein. It possesses an N-terminal signal sequence (residues 1–34), two relatively long segments predicted to form coiled coils (CC domain, residues 35–277), and a C-terminal LytM domain (residues 278–419) needed for amidase activation.