InterPro domain: IPR005527

Cytokinesis needs to be regulated spatially in order to ensure that it occurs between the daughter genomes. In prokaryotes such as Escherichia coli, cytokinesis is initiated by FtsZ, a tubulin-like protein that assembles into a ring structure at the cell centre called the Z ring. A fundamental problem in prokaryotic cell biology is to understand how the midcell division site is identified. Two major negative regulatory systems are known to be involved in preventing Z-ring assembly at all sites except the midcell. One of these systems, called nucleoid occlusion, blocks Z-ring assembly in the area occupied by an unsegregated nucleoid until a critical stage in chromosome replication or segregation is reached. The other system consists of three proteins, MinC, MinD and MinE, which prevent assembly of Z rings in regions of the cell not covered by the nucleoid, such as the cell poles. MinC is an inhibitor of FtsZ polymerisation, resulting in the inhibition of Z ring assembly in the cell; MinD greatly enhances the inhibitory effects of MinC in vivo; and MinE antagonizes the effects of MinC and MinD [ 1 ].

This entry also includes plant MinE1 located in chloroplasts. AtMinE1 acts as a topological specificity factor during plastid division and specify plastid constriction sites [ 2 ].

MinE is a small bifunctional protein. The amino terminus of MinE is required to interact with MinD, while the carboxyl terminus is required for `topological specificity' - that is, the ability of MinE to antagonise MinCD inhibition of Z rings at the midcell position but not at the poles [ 3 ].

1. Bacterial cell division: a moving MinE sweeper boggles the MinD. Curr. Biol. 11, R395-8
2. A chloroplast protein homologous to the eubacterial topological specificity factor minE plays a role in chloroplast division. Plant Physiol. 127, 1644-55
3. A division inhibitor and a topological specificity factor coded for by the minicell locus determine proper placement of the division septum in E. coli. Cell 56, 641-9