The Z Ring and Its Role in Cell Division

During cell division, the Z ring organizes the division process. It provides direction to new wall formation and enhances turnover rates near the mid-cell. There are several regulatory proteins that render the Z ring responsive to changes in cell cycle.

There are two main positions for Z ring assembly. The mid-cell and poles. While Z rings can form at either of these locations, the position at the cell centre is the most common. In most prokaryotic cells, the Z ring is synthesized from the nucleoid, but it can also be produced from other positions.

The Z ring is composed of a polymer of the FtsZ protein. It is comprised of filaments that are oriented in a similar way, allowing them to crosslink together in bundles. These filaments are subject to GTPase activity, which allows them to explore intracellular space.

The replisome controls the Z ring assembly at the mid-cell. However, replisome-mediated checkpoints have been observed to interfere with the assembly. Inhibition of the peptidoglycan synthesis proteins (PGPs) prevents the formation of a new Z ring. The Min system may also have a role in the positioning of the Z ring at the division site.

The position of the division site is highly precise in E. coli. The shape of the cell during contraction and growth is determined by the Z-ring force. The Z ring can produce a small force, as low as eight pN in E. coli. This force is accompanied by stretching, bending, and internal pressure.