一种三组分有序肌动蛋白解聚机制的单分子成像

Single-molecule imaging of a three-component ordered actin disassembly mechanism.

作者信息

Jansen Silvia, Collins Agnieszka, Chin Samantha M, Ydenberg Casey A, Gelles Jeff, Goode Bruce L

机构信息

Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, 415 South street, Waltham, Massachusetts 02454, USA.

Department of Biochemistry, Brandeis University, 415 South street, Waltham, Massachusetts 02454, USA.

出版信息

Nat Commun. 2015 May 21;6:7202. doi: 10.1038/ncomms8202.

The mechanisms by which cells destabilize and rapidly disassemble filamentous actin networks have remained elusive; however, Coronin, Cofilin and AIP1 have been implicated in this process. Here using multi-wavelength single-molecule fluorescence imaging, we show that mammalian Cor1B, Cof1 and AIP1 work in concert through a temporally ordered pathway to induce highly efficient severing and disassembly of actin filaments. Cor1B binds to filaments first, and dramatically accelerates the subsequent binding of Cof1, leading to heavily decorated, stabilized filaments. Cof1 in turn recruits AIP1, which rapidly triggers severing and remains bound to the newly generated barbed ends. New growth at barbed ends generated by severing was blocked specifically in the presence of all three proteins. This activity enabled us to reconstitute and directly visualize single actin filaments being rapidly polymerized by formins at their barbed ends while simultanteously being stochastically severed and capped along their lengths, and disassembled from their pointed ends.

细胞使丝状肌动蛋白网络不稳定并迅速解体的机制一直难以捉摸；然而，冠蛋白、丝切蛋白和AIP1已被证明参与了这一过程。在这里，我们使用多波长单分子荧光成像技术表明，哺乳动物的Cor1B、Cof1和AIP1通过一个时间有序的途径协同作用，诱导肌动蛋白丝高效切断和解聚。Cor1B首先与肌动蛋白丝结合，并显著加速随后Cof1的结合，导致肌动蛋白丝被大量修饰并稳定。Cof1进而招募AIP1，AIP1迅速触发切断，并与新产生的带刺末端结合。在所有三种蛋白质存在的情况下，切断产生的带刺末端的新生长被特异性阻断。这种活性使我们能够重建并直接观察到单个肌动蛋白丝在其带刺末端被formin快速聚合，同时沿其长度被随机切断和封端，并从其尖端末端解聚。