Bacterial Cell Division

Abstract

Bacterial cell division or cytokinesis is the process in which a bacterial cell is split into two progeny cells, each with a copy of the chromosome. In most bacteria this process in initiated by the formation of the Z ring, a dynamic structure consisting of polymers of FtsZ, a tublin family member. The Z ring recruits additional division proteins to form the septal ring, also called the divisome, which leads to the synthesis of the septum separating the progeny cells. Spatial regulation of Z-ring formation occurs primarily through negative regulators of FtsZ assembly that are positioned within the cell. The Z ring forms where the concentration of these negative regulators is at a minimum. A variety of regulators and mechanisms for positioning them have been identified in different bacteria. Among the mechanisms are the binding of a regulator to the segregating chromosome or the divisome itself and a self-organizing system.

Key concepts:

• Division depends on a cytoskeletal element (Z ring) that functions as a scaffold to recruit all the division proteins.

• Spatial regulation of Z ring placement involves positioning inhibitors of FtsZ in the cell to prevent FtsZ polymers from coalescing into the ring.

• Dynamic self-organization – the ability of proteins to form dynamic structures and patterns fuelled by nucleotide hydrolysis; the Min system produces an oscillatory pattern and FtsZ filaments have the ability to form rings when attached to a lipid bilayer that has a cylindrical shape.