The rapid onset of elasticity during the assembly of the bacterial cell-division protein FtsZ.
FtsZ, a prokaryotic homolog of eukaryotic tubulin, is a major constituent of the bacterial Z-ring, which contracts the cell wall during cell division. Because the mechanical properties of FtsZ are unknown, its function in the maintenance and constriction of the Z-ring is not well understood. Here, quantitative rheometry shows that, at physiological concentrations, FtsZ filaments form, extremely rapidly, highly elastic networks within physiological time scales ( approximately minutes), much faster than other major dynamic cytoskeletal filaments, including microtubule, actin, and vimentin in eukaryotes. FtsZ networks display a relatively low viscosity and a high resilience against shear stresses, as well as an elasticity that depends weakly on concentration, G approximately C(0.57), a power-law dependence consistent with crosslinked flexible filaments. Calcium, whose intracellular concentration increases during bacterial division, further enhances the elasticity of FtsZ networks through filament bundling, an effect that occurs in the presence of GTP, not GDP. These studies suggest that FtsZ filaments have the toughness to provide strong mechanical support for the maintenance and circumferential constriction of the bacterial Z-ring.
Esue
Osigwe
O
Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA.
Tseng
Yiider
Y
Wirtz
Denis
D
D000199:Actins / Q000032:analysis* / Q000737:chemistry*; D000818:Animals; D001426:Bacterial Proteins / Q000032:analysis / Q000737:chemistry* / Q000648:ultrastructure*; D002118:Calcium / Q000737:chemistry*; D018797:Cell Cycle Proteins / Q000032:analysis / Q000737:chemistry / Q000648:ultrastructure; D002645:Chickens; D003598:Cytoskeletal Proteins / Q000032:analysis / Q000737:chemistry* / Q000648:ultrastructure*; D004548:Elasticity; D004926:Escherichia coli / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D046912:Multiprotein Complexes / Q000032:analysis / Q000737:chemistry; D013314:Stress, Mechanical
D000199:Actins; D001426:Bacterial Proteins; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; C071525:FtsZ protein, Bacteria; D046912:Multiprotein Complexes; D002118:Calcium