Khaitlina Sofia, Tsaplina Olga, Hinssen Horst
Institute of Cytology RAS, St. Petersburg, Russia.
Faculty of Biology, University of Bielefeld, Bielefeld, Germany.
FEBS Lett. 2017 Jul;591(13):1884-1891. doi: 10.1002/1873-3468.12700. Epub 2017 Jun 11.
Tropomyosin (Tpm) plays an important role in regulating the organisation and functions of the actin cytoskeleton. Here, we describe a new approach to analyse the effects of Tpm on actin dynamics. Using F-actin proteolytically modified within the DNase-binding loop (ECP-actin), we show that Tpm binding almost completely suppresses the increased subunit exchange intrinsic for this F-actin. The effect is both concentration-dependent and cooperative, with half-maximal inhibition observed at about a 1 : 50 Tpm : actin ratio. Tpm decreases not only the number concentration of ECP-actin filaments, but also the rate of the filament subunit exchange. Our data suggest that Tpm regulates the dynamics of actin filaments by an allosteric strengthening of intermonomer contacts in the actin filament, and that this mechanism may be involved in the modulation of cytoskeletal dynamics.
原肌球蛋白（Tpm）在调节肌动蛋白细胞骨架的组织和功能方面发挥着重要作用。在此，我们描述了一种分析Tpm对肌动蛋白动力学影响的新方法。使用在脱氧核糖核酸酶结合环内进行蛋白水解修饰的F-肌动蛋白（ECP-肌动蛋白），我们发现Tpm结合几乎完全抑制了这种F-肌动蛋白固有的亚基交换增加。这种效应具有浓度依赖性和协同性，在Tpm与肌动蛋白的比例约为1:50时观察到半数最大抑制。Tpm不仅降低了ECP-肌动蛋白丝的数量浓度，还降低了丝亚基交换的速率。我们的数据表明，Tpm通过变构增强肌动蛋白丝中单体间的接触来调节肌动蛋白丝的动力学，并且这种机制可能参与细胞骨架动力学的调节。
