Center for NanoScience, Ludwig-Maximilians-University Munich, Munich, Germany.
Biophys J. 2011 Oct 19;101(8):1978-86. doi: 10.1016/j.bpj.2011.09.027.
As more and more recent investigations point out, force plays an important role in cellular regulation mechanisms. Biological responses to mechanical stress are often based on force-induced conformational changes of single molecules. The force sensor, titin kinase, is involved in a signaling complex that regulates protein turnover and transcriptional adaptation in striated muscle. The structural architecture of such a force sensor determines its response to force and must assure both activity and mechanical integrity, which are prerequisites for its function. Here, we use single-molecule force-clamp spectroscopy to show that titin kinase is organized in such a way that the regulatory domains have to unfold before secondary structure elements that determine the overall fold and catalytic function. The stepwise unfolding over many barriers with a topologically determined sequence assures that the protein can react to force by conformational changes while maintaining its structural integrity.
随着越来越多的最新研究指出，力在细胞调节机制中起着重要作用。生物对机械压力的反应通常基于单分子的力诱导构象变化。力传感器，titin 激酶，参与调节横纹肌中蛋白质周转和转录适应的信号复合物。这种力传感器的结构架构决定了它对力的响应，并且必须确保活性和机械完整性，这是其功能的前提。在这里，我们使用单分子力钳光谱法表明 titin 激酶以这样的方式组织，即调节结构域必须展开，然后才能展开决定整体折叠和催化功能的二级结构元件。通过拓扑确定的顺序进行分步展开，确保了蛋白质可以通过构象变化对力做出反应，同时保持其结构完整性。
