Active liquid crystals powered by force-sensing DNA-motor clusters
Active liquid crystals powered by force-sensing DNA-motor clusters
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DOI：
10.1073/pnas.2102873118
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发表时间：
2021-06
期刊：
影响因子：
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通讯作者：
Alexandra M. Tayar;M. Hagan;Z. Dogic
中科院分区：
文献类型：
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作者：
Alexandra M. Tayar;M. Hagan;Z. Dogic
单分子技术以前所未有的细节阐明了孤立分子马达如何产生皮牛顿力。然而，在不同的生物和合成环境中，产生力的蛋白质共同为非平衡动力学提供动力，包括连续的大规模重排和持续的流体流动。在这些密集和动态的环境中描述电机产生的力仍然是一个挑战。我们组装了一个可逆的基于DNA的力传感探针，通过光学读出，揭示了分子排列和驱动蛋白马达所经历的力负荷。这些探针提供了深入了解电机产生的力量，共同动力的微管为基础的活性向列细胞，一个值得注意的例子，内部驱动的活性物质系统的独特动态。基于DNA的力探针可以扩展到研究各种合成系统以及不同细胞环境中的力和应力。细胞骨架活性向列相分子表现出惊人的非平衡动力学，由耗能分子马达提供动力。为了深入了解这些材料的结构和力学，我们设计了可编程簇，其中驱动蛋白马达通过双链DNA接头连接。基于DNA的簇为活性向列体提供动力的效率取决于驱动蛋白马达的步进动力学和聚合物接头的化学结构。荧光各向异性测量表明，电机集群，像丝状微管，表现出当地的有序。DNA连接子的性质使得能够设计力传感簇。当连接器上的负载超过临界阈值时，簇会分解，停止生成主动应力并减缓系统动力学。荧光读数揭示了产生丝间滑动的结合簇的分数。反过来，这产生了驱动蛋白马达沿着微管步进时所经历的平均负载。DNA马达集群提供了一个基础，了解纳米级分子马达集体产生介观主动应力，这反过来又权力的宏观非平衡动力学的活性向列相的分子机制。
Significance Single-molecule techniques have elucidated how isolated molecular motors generate piconewton forces with unprecedented detail. However, in diverse biological and synthetic settings, force-generating proteins collectively power nonequilibrium dynamics, including continuous large-scale rearrangements and persistent fluid flows. Characterizing motor-generated forces in these dense and dynamical environments remains a challenge. We assembled a reversible DNA-based force-sensing probe that, by an optical readout, reveals the molecular arrangements and the force loads experienced by kinesin motors. These probes provide insight into motor-generated forces that collectively power the unique dynamics of microtubule-based active nematics, a noteworthy example of an internally driven active matter system. DNA-based force probes can be extended to study forces and stresses in various synthetic systems as well as diverse cellular environments. Cytoskeletal active nematics exhibit striking nonequilibrium dynamics that are powered by energy-consuming molecular motors. To gain insight into the structure and mechanics of these materials, we design programmable clusters in which kinesin motors are linked by a double-stranded DNA linker. The efficiency by which DNA-based clusters power active nematics depends on both the stepping dynamics of the kinesin motors and the chemical structure of the polymeric linker. Fluorescence anisotropy measurements reveal that the motor clusters, like filamentous microtubules, exhibit local nematic order. The properties of the DNA linker enable the design of force-sensing clusters. When the load across the linker exceeds a critical threshold, the clusters fall apart, ceasing to generate active stresses and slowing the system dynamics. Fluorescence readout reveals the fraction of bound clusters that generate interfilament sliding. In turn, this yields the average load experienced by the kinesin motors as they step along the microtubules. DNA-motor clusters provide a foundation for understanding the molecular mechanism by which nanoscale molecular motors collectively generate mesoscopic active stresses, which in turn power macroscale nonequilibrium dynamics of active nematics.