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Updated: Jun 6, 2026

Probing Myosin Ensemble Mechanics in Actin Filament Bundles Using Optical Tweezers
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Published on: May 4, 2022

Dynamics of the β-cardiac myosin auto-inhibited state explain cardiomyopathy pathogenesis

Daniel Auguin1,2, Laurie Lannes1, Carlos Kikuti1

  • 1Structural Motility, CNRS UMR144, Institut Curie, Sorbonne Université, Université Paris Sciences et Lettres, Paris, France.

Nature Communications
|June 4, 2026
PubMed

Insights

Understanding the cardiac myosin interacting-heads motif (CarIHM) is key for cardiac contractility. This study reveals how CarIHM dynamics regulate muscle contraction and how mutations impact heart function.

Area of Science:

  • Cardiovascular Biology
  • Structural Biology
  • Biophysics

Background:

  • Cardiac contractility relies on precise myosin regulation.
  • The beta-cardiac myosin off-state, or Interacting-Heads Motif (CarIHM), is a critical regulator.
  • Structural dynamics of CarIHM are poorly understood, hindering insights into cardiac function and disease.

Purpose of the Study:

  • To structurally and dynamically characterize the CarIHM in solution and within the cardiac filament.
  • To elucidate the role of CarIHM conformational ensembles in myosin regulation.
  • To investigate the impact of the E525K dilated cardiomyopathy mutation on CarIHM structure and dynamics.

Main Methods:

  • Integration of near-atomic resolution cryo-electron microscopy (cryo-EM).
  • All-atom molecular dynamics simulations.
  • Analysis of intrinsically disordered regions in CarIHM and MyBP-C.

Main Results:

  • Characterization of CarIHM conformational ensembles regulated by dynamic interfaces.
  • Demonstration of the stabilizing effect of the E525K mutation, limiting S2 coiled-coil flexibility and impairing myosin activation.
  • Identification of modulation of dynamics by intrinsically disordered regions of CarIHM and MyBP-C.

Conclusions:

  • CarIHM ensembles balance myosin off/on states and anchor heads within the thick filament.
  • The study provides a mechanistic understanding of thick filament regulation.
  • Findings facilitate predictions for genetic variants in inherited cardiomyopathies.

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