Abstract
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.
Highlights
The mechanisms by which cells destabilize and rapidly disassemble filamentous actin networks have remained elusive; Coronin, Cofilin and AIP1 have been implicated in this process
Even though Cofilin is present at concentrations of 5–20 mM in mammalian cells[10,11,12], maximal severing by Cofilin in vitro was observed at nanomolar concentrations, and micromolar concentrations of Cofilin perplexingly led to overdecoration and stabilization of filaments[8,13]
10-fold lower concentrations of Cor1B and AIP1, we observed complete severing and disassembly of filaments (10–15 mm in length) only 5 s after flow-in (Fig. 1a; Supplementary Movie 1)
Summary
The mechanisms by which cells destabilize and rapidly disassemble filamentous actin networks have remained elusive; Coronin, Cofilin and AIP1 have been implicated in this process. New growth at barbed ends generated by severing was blocked 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. Even though Cofilin is present at concentrations of 5–20 mM in mammalian cells[10,11,12], maximal severing by Cofilin in vitro was observed at nanomolar concentrations, and micromolar concentrations of Cofilin perplexingly led to overdecoration and stabilization of filaments[8,13] It has been unclear how actin polymerization is prevented at the new barbed ends of filaments generated by severing. Mounting genetic and biochemical evidence has implicated three proteins (Srv2/CAP, AIP1 and Coronin) in functioning with
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
