Fig 7. Comparison of the mechanisms used by negative regulators of FtsZ assembly.

FtsZ monomers are depicted as having one nucleotide molecule, either GDP or GTP. Polymers form once the concentration of nucleotide-charged monomers reaches a threshold (the critical concentration), arbitrarily fixed here as a minimum of four monomers in a field (top row). FtsZ contained inside polymers displays a GTPase activity. The action of SulA dimers (second row) prevents polymerization by removing two FtsZ monomers from the available pool while locking them in a relative orientation that precludes the assembly of a GTPase active site. As a result the critical concentration is not reached and FtsZ tends to remain as monomers. MinC dimers (third row) interfere with already formed FtsZ filaments dissociating them into shorter polymers of narrowly distributed sizes. SlmA (fourth row) forms dimers of dimers when associated to DNA sequences in the nucleoid. The SlmA SBS complexes dissociate FtsZ polymers yielding shorter polymers of a variety of sizes.