Practice question

Accurate division requires Z ring forms only at midcell between segregated chromosomes preventing minicell formation anucleate wasted progeny. Min system provides positional information via reaction diffusion oscillation. MinD ATPase dimer binds membrane, recruits MinC FtsZ inhibitor blocking polymerization, MinE stimulates MinD ATPase causing release, complex cycles pole to pole with period about 1 minute resulting concentration minima at center where FtsZ can assemble. Second safeguard nucleoid occlusion proteins SlmA in Escherichia coli and Noc in Bacillus bind DNA and directly inhibit FtsZ assembly over chromosome, ensuring septum forms only after chromosome segregation complete. Thus Min system prevents Z ring formation at bacterial poles by preventing FtsZ polymerization at incorrect sites rather than degrading divisome proteins or inhibiting MreB which controls elongation, nor activating crescentin. Mutants lacking MinCDE display polar Z rings producing minicells small spherical chromosome less particles, phenotype used to discover system and model Turing pattern formation in vivo.