Analysis of MinC reveals two independent domains involved in interaction with MinD and FtsZ

In Escherichia coil FtsZ assembles into a Z ring at midcell while assembly at polar sites is prevented by the min system. MinC, a component of this sy stem, is an inhibitor of FtsZ assembly that is positioned within the cell b y interaction with MinDE. In this study we found that MinC consists of two functional domains connected by a short linker. When fused to MalE the N-te rminal domain is able to inhibit cell division and prevent FtsZ assembly in vitro. The C-terminal domain interacts with MinD, and expression in wild-t ype cells as a MalE fusion disrupts min function, resulting in a minicell p henotype. We also find that MinC is an oligomer, probably a dimer. Although the C-terminal domain is clearly sufficient for oligomerization, the N-ter minal domain also promotes oligomerization. These results demonstrate that MinC consists of two independently functioning domains: an N-terminal domai n capable of inhibiting FtsZ assembly and a C-terminal domain responsible f or localization of MinC through interaction with MinD. The fusion of these two independent domains is required to achieve topological regulation of Z ring assembly.