MinC spatially controls bacterial cytokinesis by antagonizing the scaffolding function of FtsZ.
BACKGROUND
Cytokinesis in bacteria is mediated by a cytokinetic ring, termed the Z ring, which forms a scaffold for recruitment of other cell-division proteins. The Z ring is composed of FtsZ filaments, but their organization in the Z ring is poorly understood. In Escherichia coli, the Min system contributes to the spatial regulation of cytokinesis by preventing the assembly of the Z ring away from midcell. The effector of the Min system, MinC, inhibits Z ring assembly by a mechanism that is not clear.


RESULTS
Here, we report that MinC controls the scaffolding function of FtsZ by antagonizing the mechanical integrity of FtsZ structures. Specifically, MinC antagonizes the ability of FtsZ filaments to be in a solid-like gel state. MinC is a modular protein whose two domains (MinC(C) and MinC(N)) synergize to inhibit FtsZ function. MinC(C) interacts directly with FtsZ polymers to target MinC to Z rings. MinC(C) also prevents lateral interactions between FtsZ filaments, an activity that seems to be unique among cytoskeletal proteins. Because MinC(C) is inhibitory in vivo, it suggests that lateral interactions between FtsZ filaments are important for the structural integrity of the Z ring. MinC(N) contributes to MinC activity by weakening the longitudinal bonds between FtsZ molecules in a filament leading to a loss of polymer rigidity and consequent polymer shortening. On the basis of our results, we develop the first computational model of the Z ring and study the effects of MinC.


CONCLUSIONS
Control over the scaffolding activity of FtsZ probably represents a universal regulatory mechanism of bacterial cytokinesis.
Dajkovic
Alex
A
Department of Chemical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA. alex.dajkovic@curie.fr
Lan
Ganhui
G
Sun
Sean X
SX
Wirtz
Denis
D
Lutkenhaus
Joe
J
D001426:Bacterial Proteins / Q000378:metabolism* / Q000648:ultrastructure; D002352:Carrier Proteins / Q000378:metabolism; D048749:Cytokinesis / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000378:metabolism* / Q000648:ultrastructure; D004926:Escherichia coli / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D029968:Escherichia coli Proteins / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000378:metabolism; D005782:Gels; D008565:Membrane Proteins / Q000378:metabolism*; D008954:Models, Biological; D033902:Periplasmic Binding Proteins / Q000378:metabolism*; D011108:Polymers / Q000378:metabolism
D001426:Bacterial Proteins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D029968:Escherichia coli Proteins; C071525:FtsZ protein, Bacteria; D005782:Gels; C461619:MalE protein, E coli; D008565:Membrane Proteins; C462942:MinC protein, E coli; D033902:Periplasmic Binding Proteins; D011108:Polymers; C520744:ZapA protein, E coli; D020558:GTP Phosphohydrolases