Physik Department E22, Technische Universität München, 85748 Garching, Germany.
Proc Natl Acad Sci U S A. 2012 Nov 27;109(48):19679-84. doi: 10.1073/pnas.1211274109. Epub 2012 Nov 13.
Mechanical forces are important signals for cell response and development, but detailed molecular mechanisms of force sensing are largely unexplored. The cytoskeletal protein filamin is a key connecting element between the cytoskeleton and transmembrane complexes such as integrins or the von Willebrand receptor glycoprotein Ib. Here, we show using single-molecule mechanical measurements that the recently reported Ig domain pair 20-21 of human filamin A acts as an autoinhibited force-activatable mechanosensor. We developed a mechanical single-molecule competition assay that allows online observation of binding events of target peptides in solution to the strained domain pair. We find that filamin force sensing is a highly dynamic process occurring in rapid equilibrium that increases the affinity to the target peptides by up to a factor of 17 between 2 and 5 pN. The equilibrium mechanism we find here can offer a general scheme for cellular force sensing.
机械力是细胞反应和发育的重要信号，但力感应的详细分子机制在很大程度上仍未被探索。细胞骨架蛋白细丝蛋白是细胞骨架与跨膜复合物（如整合素或 von Willebrand 受体糖蛋白 Ib）之间的关键连接元件。在这里，我们使用单分子力学测量表明，最近报道的人源细丝蛋白 A 的 Ig 结构域对 20-21 充当自动抑制的力激活机械传感器。我们开发了一种机械单分子竞争测定法，该测定法允许在线观察溶液中目标肽与应变结构域对的结合事件。我们发现，细丝蛋白的力感应是一个快速平衡的高度动态过程，在 2 到 5 pN 之间将与目标肽的亲和力提高多达 17 倍。我们在这里发现的平衡机制可以为细胞力感应提供一个通用方案。
