Block Johanna, Witt Hannes, Candelli Andrea, Danes Jordi Cabanas, Peterman Erwin J G, Wuite Gijs J L, Janshoff Andreas, Köster Sarah
Institute for X-Ray Physics, University of Goettingen, 37077 Göttingen, Germany.
Institute of Physical Chemistry, University of Goettingen, 37077 Göttingen, Germany.
Sci Adv. 2018 Jun 13;4(6):eaat1161. doi: 10.1126/sciadv.aat1161. eCollection 2018 Jun.
Structure and dynamics of living matter rely on design principles fundamentally different from concepts of traditional material science. Specialized intracellular filaments in the cytoskeleton permit living systems to divide, migrate, and grow with a high degree of variability and durability. Among the three filament systems, microfilaments, microtubules, and intermediate filaments (IFs), the physical properties of IFs and their role in cellular mechanics are the least well understood. We use optical trapping of individual vimentin filaments to investigate energy dissipation, strain history dependence, and creep behavior of stretched filaments. By stochastic and numerical modeling, we link our experimental observations to the peculiar molecular architecture of IFs. We find that individual vimentin filaments display tensile memory and are able to dissipate more than 70% of the input energy. We attribute these phenomena to distinct nonequilibrium folding and unfolding of α helices in the vimentin monomers constituting the filaments.
生命物质的结构与动力学依赖于与传统材料科学概念截然不同的设计原则。细胞骨架中的特化细胞内细丝使生命系统能够高度可变且持久地进行分裂、迁移和生长。在微丝、微管和中间丝（IFs）这三种细丝系统中，中间丝的物理性质及其在细胞力学中的作用是了解最少的。我们利用对单个波形蛋白细丝的光镊技术来研究拉伸细丝的能量耗散、应变历史依赖性和蠕变行为。通过随机和数值建模，我们将实验观察结果与中间丝独特的分子结构联系起来。我们发现单个波形蛋白细丝表现出拉伸记忆，并且能够耗散超过70%的输入能量。我们将这些现象归因于构成细丝的波形蛋白单体中α螺旋的独特非平衡折叠和展开。
