发表机构
Georgia Institute of Technology; University of Colorado Boulder; University of Chicago; Drake University（佐治亚理工学院; 科罗拉多大学博尔德分校; 芝加哥大学; 德雷克大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用光镊微流变学揭示Ca$^{2+}$浓度从1至100 mM可提升Tcb2网络刚度近两个数量级，并发现正交拉伸后沿对角线回弹，确立其为研究化学-力学耦合的最小可调系统。
AI 中文摘要
四膜虫钙结合蛋白（Tcb2）可形成响应Ca$^{2+}$的收缩性网络，但Ca$^{2+}$浓度如何控制其局部力学响应仍知之甚少。本研究利用光镊在微流控装置内对重组Tcb2网络进行主动微流变学测量，该装置可精确控制Ca$^{2+}$浓度，从而系统调节网络结构与力学性质。研究发现，将Ca$^{2+}$浓度从1 mM增加至100 mM可使有效刚度提升近两个数量级，从约1×10$^{-3}$ pN/nm增至约7×10$^{-2}$ pN/nm，对应网络从黏性主导转变为更具弹性且力学上更稳健的状态。回弹实验进一步揭示了变形后储存弹性能的快速释放。在两次正交拉伸后，微珠沿对角线方向回弹而非沿加载路径返回，表明不同方向的应力组合产生合恢复响应。这些结果确立了Tcb2网络作为研究Ca$^{2+}$调控蛋白网络中化学-力学耦合与黏弹性的最小可调系统。
英文摘要
Tetrahymena calcium-binding protein (Tcb2) forms Ca$^{2+}$-responsive networks that exhibit contractile behavior, yet how Ca$^{2+}$ concentration controls their local mechanical response remains poorly understood. Here, we use optical tweezers to perform active microrheology on reconstituted Tcb2 networks inside a microfluidic device that enables precise control of Ca$^{2+}$ concentration, allowing systematic tuning of network structure and mechanics. We find that increasing Ca$^{2+}$ from 1 to 100~mM enhances the effective stiffness by nearly two orders of magnitude, from $\sim$1$\times$10$^{-3}$ to $\sim$7$\times$10$^{-2}$~pN/nm, corresponding to a transition from a viscosity-dominated to a more elastic and mechanically robust network. Recoil assays further reveal rapid release of stored elastic energy following deformation. After two orthogonal pulls, the bead recoils along the diagonal rather than retracing the loading path, indicating that stresses from different directions combine to produce a resultant restoring response. These results establish Tcb2 networks as a minimal, tunable system for probing chemomechanical coupling and viscoelasticity in Ca$^{2+}$-regulated protein networks.
