Assembly Dynamics of the Bacterial MinCDE System and Spatial Regulation of the Z Ring

Abstract

The positioning of a cytoskeletal element that dictates the division plane is a fundamental problem in biology. The assembly and positioning of this cytoskeletal element has to be coordinated with DNA segregation and cell growth to ensure that equal-sized progeny cells are produced, each with a copy of the chromosome. In most prokaryotes, cytokinesis involves positioning a Z ring assembled from FtsZ, the ancestral homologue of tubulin. The position of the Z ring is determined by a gradient of negative regulators of Z-ring assembly. In Escherichia coli, the Min system consists of three proteins that cooperate to position the Z ring through a fascinating oscillation, which inhibits the formation of the Z ring away from midcell. Additional gradients of negative regulators of FtsZ assembly are used by E. coli and other bacteria to achieve spatial control of Z-ring assembly.

Modeling Three-Dimensional Spatial Regulation of Bacterial Cell Division (Dissertation)

“…Recent advances in molecular biology suggest that modeling reaction networks alone is not sufficient to accurately reproduce certain important cellular processes such as cell division (Lutkenhaus, 2007) and gene expression (Talbert and Henikoff, 2006). In Chapter 1 we have reviewed how the physical location, crowding and diffusion of molecules in cell compartments play crucial roles in these processes.…”

“…In the rod-shaped bacterium Escherichia coli for example, the Min system of proteins (Lutkenhaus, 2007), comprising MinC, MinD and MinE, oscillates from one pole to the other to direct the position of division to the middle of the cell long axis. By dividing in the middle, the cell ensures equal distribution of its contents to the two daughter cells.…”

Dynamics of bacterial cytoskeletal elements

“…Both proteins directly interact with FtsZ, and thus perform redundant functions in membrane targeting of FtsZ [Hale et al, 2000;Pichoff and Lutkenhaus, 2005]. The positioning of the Z-ring is primarily regulated through the prevention of FtsZ polymerisation at the cell poles, achieved by the Min system [Rothfield et al, 2005;Lutkenhaus, 2007], or by a newly recognized regulatory system [Thanbichler and Shapiro, 2006], and by the Noc/SlmA system, which prevents Zring formation over the nucleoid [Wu and Errington, 2004;Bernhardt and de Boer, 2005], which usually occupies the central part of the cell. The combined action of the Min and the Noc systems only leave the cell centre free for polymerisation of FtsZ, when sister chromosomes are largely segregated towards opposite cell poles.…”

“…The combined action of the Min and the Noc systems only leave the cell centre free for polymerisation of FtsZ, when sister chromosomes are largely segregated towards opposite cell poles. Several proteins additionally regulate the polymerisation of FtsZ, several recent reviews discuss these aspects of bacterial cell division [Rothfield et al, 2005;Graumann, 2007;Lutkenhaus, 2007].…”

“…These proteins form sheet-like filaments in the presence of ATP, and have ATPase activity [Lutkenhaus, 2007]. In vivo, ParA/MinD proteins have been shown to form the now classical pattern of helical filaments [Shih et al, 2003], which in the case of MinD oscillate from one pole of the cell to the other in a matter of few seconds [Raskin and de Boer, 1999].…”