近日，奥地利科技学院的Martin Loose&Edouard Hannezo及其研究团队取得一项新进展。经过不懈努力，他们揭示柔性活性细丝的手性相和向列相。相关研究成果已于2023年10月9日在国际知名学术期刊《自然—物理学》上发表。

本文结合最小活性物质模拟和生化重构实验，将单丝特性与介观尺度联系起来。研究人员证明了活性手性细丝的密度和柔韧性决定了它们的全局顺序。在中等密度时，弯曲的柔韧细丝组织成手性环和极性带。在高密度和直的、突变的刚性增加的细丝中，有效的向列组织占主导地位。他们预测的相图定量地捕捉了这些特征，展示了活性细丝的柔韧性、密度和手性如何影响它们的集体行为。这一研究发现揭示了活性手性物质的基本特性，并解释了在细菌细胞分裂过程中，FtsZ细丝是如何组织的。

据悉，自组织系统中大规模顺序的出现依赖于单个组件之间的局部相互作用。在细菌细胞分裂过程中，FtsZ（真核蛋白微管蛋白的原核同源物）聚合成踏车式细丝，进一步组织成细胞骨架环。在体外，FtsZ细丝可以形成动态手性组装体。然而，单个细丝的主动和被动特性与这些大规模自组织结构的关系仍然知之甚少。

附：英文原文

Title: Chiral and nematic phases of flexible active filaments

Author: Dunajova, Zuzana, Mateu, Batirtze Prats, Radler, Philipp, Lim, Keesiang, Brandis, Drte, Velicky, Philipp, Danzl, Johann Georg, Wong, Richard W., Elgeti, Jens, Hannezo, Edouard, Loose, Martin

Issue&Volume: 2023-10-09

Abstract: 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.

DOI: 10.1038/s41567-023-02218-w

Source: https://www.nature.com/articles/s41567-023-02218-w