The force-induced unfolding and refolding of proteins is speculated to be a key mechanism in the sensing and transduction of mechanical signals in the living cell. Yet, little evidence has been gathered for its existence in vivo. To test the occurrence of mechanical kinase activation in living working muscle, we generated transgenic C. elegans expressing twitchin containing FRET moieties flanking the kinase domain and measured FRET signals in freely moving C. elegans. The data revealed statistically significant periodic changes in FRET signals during muscle activity, consistent with a periodic change in the conformation of twitchin kinase. We conclude that stretch-unfolding of twitchin kinase occurs in the active muscle, whereby mechanical activity titrates the signalling pathway of this cytoskeletal kinase. We anticipate that the methods could be applied to obtaining in vivo evidence for force-induced conformational changes or elastic behavior of other proteins in C. elegans and other animals.

中文翻译：

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自由移动的秀丽隐杆线虫的FRET成像揭示了体内Twitchin激酶的构象变化

力诱导的蛋白质解折叠和重折叠被认为是在活细胞中感测和传递机械信号的关键机制。然而，几乎没有证据表明其在体内存在。为了测试在活的工作肌肉中机械激酶激活的发生，我们生成了表达含线虫的转基因线虫，该线虫含有位于激酶结构域两侧的FRET部分，并在自由移动的线虫中测量了FRET信号。数据显示，在肌肉活动过程中，FRET信号在统计学上具有显着的周期性变化，这与twitchin激酶构象的周期性变化相一致。我们得出结论，twitchin激酶的拉伸解折叠发生在活跃的肌肉中，由此机械活性滴定了这种细胞骨架激酶的信号传导途径。