Placement of the division septum in E. coli is negatively regulated by the three proteins encoded by the minBoperon: MinC, MinD, and MinE. MinC and MinD act in concert to form a global division inhibitor whose activity is restricted to polar sites by MinE. In the presence of MinE all three proteins undergo a bipolar oscillation that causes the time-averaged concentration of MinCD to be lowest at midcell, the preferred division site. The MinE topological specificity domain forms a novel absandwich in which two a helices lie atop a four-strandedb sheet. Mutation of the a-face residues shown in red causes a defect in MinCD oscillation with a resultant decrease in the topological fidelity of cell division.
King, G.F., Shih, Y.-L., Maciejewski, M.W., Bains, N.P.S., Pan, B., Rowland, S.L., Mullen, G.P. and Rothfield, L.I. (2000) Structural basis for the topological specificity function of MinE. Nature Structural Biology 7, 1013-1017.