Formation of regularly spaced networks as a general feature of actin bundle condensation by entropic forces
Formation of regularly spaced networks as a general feature of actin bundle condensation by entropic forces
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DOI：
10.1088/1367-2630/17/4/043029
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发表时间：
2015-04-15
影响因子：
3.3
通讯作者：
Kaes, Josef
中科院分区：
文献类型：
--
作者：
Huber, Florian;Strehle, Dan;Kaes, Josef
生物聚合物网络有助于活细胞的机械完整性以及功能组织。它们的主要成分之一，蛋白质肌动蛋白，存在于各种不同的网络结构中，从广泛的网络到密集的束。网络的形状与其机械性能和基本生理功能直接相关。然而，对结构决定机制及其物理约束的深刻理解仍然是难以捉摸的。我们使用实验自下而上的系统来研究由熵力形成的受限肌动蛋白网络。基于分子拥挤和反凝聚的实验揭示了均匀细丝溶液聚集成由紫菀样中心连接的规则肌动蛋白束网络的一般趋势。发现网络结构严重依赖于网络形成历史。从相同的生化成分，我们观察到急剧变化的网络结构作为一个结果，最初有偏见的细丝取向或混合诱导的扰动。我们的实验表明，形成规则间隔的束网络的趋势是一个相当普遍的各向同性，均匀的细丝解决方案受到统一的吸引力的相互作用的功能。由于所考虑的相互作用的基本性质，我们预计，所研究的网络形成的类型进一步意味着严重的物理约束的细胞骨架自组织在更复杂的水平上的活细胞。
Biopolymer networks contribute mechanical integrity as well as functional organization to living cells. One of their major constituents, the protein actin, is present in a large variety of different network architectures, ranging from extensive networks to densely packed bundles. The shape of the network is directly linked to its mechanical properties and essential physiological functions. However, a profound understanding of architecture-determining mechanisms and their physical constraints remains elusive. We use experimental bottom-up systems to study the formation of confined actin networks by entropic forces. Experiments based on molecular crowding as well as counterion condensation reveal a generic tendency of homogeneous filament solutions to aggregate into regular actin bundle networks connected by aster-like centers. The network architecture is found to critically rely on network formation history. Starting from identical biochemical compositions, we observe drastic changes in network architecture as a consequence of initially biased filament orientation or mixing-induced perturbations. Our experiments suggest that the tendency to form regularly spaced bundle networks is a rather general feature of isotropic, homogeneous filament solutions subject to uniform attractive interactions. Due to the fundamental nature of the considered interactions, we expect that the investigated type of network formation further implies severe physical constraints for cytoskeleton self-organization on the more complex level of living cells.