Molecular mechanism of actin filament elongation by formins Journal Articles uri icon

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  • Formins control the assembly of actin filaments (F-actin) that drive cell morphogenesis and motility in eukaryotes. However, their molecular interaction with F-actin and their mechanism of action remain unclear. In this work, we present high-resolution cryo–electron microscopy structures of F-actin barbed ends bound by three distinct formins, revealing a common asymmetric formin conformation imposed by the filament. Formation of new intersubunit contacts during actin polymerization sterically displaces formin and triggers its translocation. This “undock-and-lock” mechanism explains how actin-filament growth is coordinated with formin movement. Filament elongation speeds are controlled by the positioning and stability of actin-formin interfaces, which distinguish fast and slow formins. Furthermore, we provide a structure of the actin-formin-profilin ring complex, which resolves how profilin is rapidly released from the barbed end during filament elongation.


  • Oosterheert, Wout
  • Boiero Sanders, Micaela
  • Funk, Johanna
  • Prumbaum, Daniel
  • Raunser, Stefan
  • Bieling, Peter

publication date

  • April 12, 2024