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Updated: Aug 7, 2026

Super-resolution Imaging of the Bacterial Division Machinery
Published on: January 21, 2013
Activation of cell division protein FtsZ. Control of switch loop T3 conformation by the nucleotide gamma-phosphate
J F Díaz1, A Kralicek, J Mingorance
1Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Cientificas, C/Velázquez, 144, 28006 Madrid, Spain. fer@akilonia.cib.csic.es
Abstract:
The effect of bound nucleotide on the conformation of cell division protein FtsZ from Methanococcus jannaschii has been investigated using molecular dynamics and site-directed mutagenesis. The molecular dynamics indicate that the gamma-phosphate of GTP induces a conformational perturbation in loop T3 (Gly88-Gly99 segment), in a position structurally equivalent to switch II of Ha-ras-p21. In the simulated GTP-bound state, loop T3 is pulled by the gamma-phosphate into a more compact conformation than with GDP, related to that observed in the homologous proteins alpha- and beta-tubulin. The existence of a nucleotide-induced structural change in loop T3 has been confirmed by mutating Thr92 into Trp (T92W-W319Y FtsZ). This tryptophan (12 A away from gamma-phosphate) shows large differences in fluorescence emission, depending on which nucleotide is bound to FtsZ monomers. Loop T3 is located at a side of the contact interface between two FtsZ monomers in the current model of FtsZ filament. Such a structural change may bend the GDP filament upon hydrolysis by pushing against helix H8 of next monomer, thus, generating force on the membrane during cell division. A related curvature mechanism may operate in tubulin activation.
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