The emergence of large-scale order in self-organized systems relies on local interactions between individual components. During bacterial cell division, FtsZ—a prokaryotic homologue of the eukaryotic protein tubulin—polymerizes into treadmilling filaments that further organize into a cytoskeletal ring. In vitro, FtsZ filaments can form dynamic chiral assemblies. However, how the active and passive properties of individual filaments relate to these large-scale self-organized structures remains poorly understood. Here we connect single-filament properties with the mesoscopic scale by combining minimal active matter simulations and biochemical reconstitution experiments. We show that the density and flexibility of active chiral filaments define their global order. At intermediate densities, curved, flexible filaments organize into chiral rings and polar bands. An effectively nematic organization dominates for high densities and for straight, mutant filaments with increased rigidity. Our predicted phase diagram quantitatively captures these features, demonstrating how the flexibility, density and chirality of the active filaments affect their collective behaviour. Our findings shed light on the fundamental properties of active chiral matter and explain how treadmilling FtsZ filaments organize during bacterial cell division.
This work was supported by the European Research Council through grant ERC 2015-StG-679239 and by the Austrian Science Fund (FWF) StandAlone P34607 to M.L., B. P.M. was also supported by the Kanazawa University WPI- NanoLSI Bio-SPM collaborative research program. Z.D. has received funding from Doctoral Programme of the Austrian Academy of Sciences (OeAW): Grant agreement 26360. We thank Jan Brugues (MPI CBG, Dresden, Germany), Andela Saric (ISTA, Klosterneuburg, Austria), Daniel Pearce (Uni Geneva, Switzerland) for valuable scientific input and comments on the manuscript. We are also thankful for the support by the Scientific Service Units (SSU) of IST Austria through resources provided by the Imaging and Optics Facility (IOF) and the Lab Support Facility (LSF).
Dunajova Z, Prats Mateu B, Radler P, et al. Chiral and nematic phases of flexible active filaments. Nature Physics. 2023. doi:10.1038/s41567-023-02218-w
Dunajova, Z., Prats Mateu, B., Radler, P., Lim, K., Brandis, D., Velicky, P., … Loose, M. (2023). Chiral and nematic phases of flexible active filaments. Nature Physics. Springer Nature. https://doi.org/10.1038/s41567-023-02218-w
Dunajova, Zuzana, Batirtze Prats Mateu, Philipp Radler, Keesiang Lim, Dörte Brandis, Philipp Velicky, Johann G Danzl, et al. “Chiral and Nematic Phases of Flexible Active Filaments.” Nature Physics. Springer Nature, 2023. https://doi.org/10.1038/s41567-023-02218-w.
Z. Dunajova et al., “Chiral and nematic phases of flexible active filaments,” Nature Physics. Springer Nature, 2023.
Dunajova Z, Prats Mateu B, Radler P, Lim K, Brandis D, Velicky P, Danzl JG, Wong RW, Elgeti J, Hannezo EB, Loose M. 2023. Chiral and nematic phases of flexible active filaments. Nature Physics.
Dunajova, Zuzana, et al. “Chiral and Nematic Phases of Flexible Active Filaments.” Nature Physics, Springer Nature, 2023, doi:10.1038/s41567-023-02218-w.
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