The C-terminus of MinE from Neisseria gonorrhoeae acts as a topological specificity factor by modulating MinD activity in bacterial cell division.

MinE regulates the proper placement of the cytokinetic FtsZ ring at midcell by inducing the pole-to-pole movement of MinCD complexes. While the N-terminus of MinE has been implicated in MinD binding, a clear functional role of the C-terminus has not been elucidated. We previously determined that MinE from Neisseria gonorrhoeae (Ng) was functional in Escherichia coli (Ec). Thus, using E. coli as a model organism, gonococcal MinE (MinE(Ng)) function was examined by generating amino acid substitutions of highly conserved MinE(Ng) residues and by testing the ability of the mutant proteins to interact with gonococcal MinD (MinD(Ng)), to induce a minicell phenotype upon overexpression, to initiate MinD(Ng) oscillation, and to stimulate MinD(Ng) ATPase activity. N-terminal MinE(Ng) mutants were unable to bind to MinD(Ng); thus, they did not induce a minicell phenotype, promote MinD(Ng) oscillation or stimulate MinD(Ng) ATPase activity. While C-terminal MinE(Ng) mutants exhibited reduced abilities to bind to MinD(Ng), we show that differences in MinD(Ng) binding to the C-terminus of MinE(Ng) alter the ability of MinE(Ng) to properly stimulate MinD(Ng) activity. We present four major findings from our studies of MinE(Ng): both the N- and C-termini of MinE(Ng) interact with MinD(Ng); interaction between MinD(Ng) and MinE(Ng) is required for the recruitment of MinD(Ng) to the coiled array; oscillation of MinD(Ng) does not require ATPase stimulation; and, the extent of MinD(Ng) ATPase stimulation depends on the binding strength between MinD(Ng) and the C-terminus of MinE(Ng.).