Helical motors and formins synergize to compact chiral filopodial bundles: A theoretical perspective

Ondrej Maxian, Alex Mogilner

Research output: Contribution to journalArticlepeer-review


Chiral actin bundles have been shown to play an important role in cell dynamics, but our understanding of the molecular mechanisms which combine to generate chirality remains incomplete. To address this, we numerically simulate a crosslinked filopodial bundle under the actions of helical myosin motors and/or formins and examine the collective buckling and twisting of the actin bundle. We first show that a number of proposed mechanisms to buckle polymerizing actin bundles without motor activity fail under biologically-realistic parameters. We then demonstrate that a simplified model of myosin spinning action at the bundle base effectively “braids” the bundle, but cannot control compaction at the fiber tips. Finally, we show that formin-mediated polymerization and motor activity can act synergitically to compact filopodium bundles, as motor activity bends filaments into shapes that activate twist forces induced by formins. Stochastic fluctuations of actin polymerization rates and slower cross linking dynamics both increase buckling and decrease compaction. We discuss implications of our findings for mechanisms of cytoskeletal chirality.

Original languageEnglish (US)
Article number151383
JournalEuropean Journal of Cell Biology
Issue number1
StatePublished - Mar 2024


  • Actin bundle
  • Chirality
  • Filament buckling
  • Filopodium
  • Formin
  • Twisting

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology
  • Cell Biology


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