Wagner B, Tharmann R, Haase I, Fischer M, Bausch A R
Lehrstühle für Biophysik E22 and Organische Chemie und Biochemie, Technische Universität München, 80333 Munich, Germany.
Proc Natl Acad Sci U S A. 2006 Sep 19;103(38):13974-8. doi: 10.1073/pnas.0510190103. Epub 2006 Sep 8.
In living cells the mechanical properties of the actin cytoskeleton are defined by the local activation of different actin cross-linking proteins. These proteins consist of actin-binding domains that are separated and geometrically organized by different numbers of rod domains. The detailed molecular structure of the cross-linking molecules determines the structural and mechanical properties of actin networks in vivo. In this study, we systematically investigate the impact of the length of the spacing unit between two actin-binding domains on in vitro actin networks. Such synthetic cross-linkers reveal that the shorter the constructs are, the greater the elastic modulus changes in the linear response regime. Because the same binding domains are used in all constructs, only the differences in the number of rod domains determine their mechanical effectiveness. Structural rearrangements of the networks show that bundling propensity is highest for the shortest construct. The nonlinear mechanical response is affected by the molecular structure of the cross-linker molecules, and the observed critical strains and fracture stress increase proportional to the length of the spacing unit.
在活细胞中，肌动蛋白细胞骨架的力学特性由不同肌动蛋白交联蛋白的局部激活所定义。这些蛋白质由肌动蛋白结合结构域组成，这些结构域由不同数量的杆状结构域分隔并按几何方式组织。交联分子的详细分子结构决定了体内肌动蛋白网络的结构和力学特性。在本研究中，我们系统地研究了两个肌动蛋白结合结构域之间间隔单元长度对体外肌动蛋白网络的影响。这种合成交联剂表明，构建体越短，线性响应范围内的弹性模量变化就越大。由于所有构建体都使用相同的结合结构域，只有杆状结构域数量的差异决定了它们的力学有效性。网络的结构重排表明，最短构建体的成束倾向最高。非线性力学响应受交联剂分子的分子结构影响，观察到的临界应变和断裂应力与间隔单元的长度成正比增加。
