Human cardiac myosin-binding protein C phosphorylation- and mutation-dependent structural dynamics monitored by time-resolved FRET

Rhye Samuel Kanassatega, Thomas A. Bunch, Victoria C. Lepak, Christopher Wang, Brett A. Colson

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Cardiac myosin-binding protein C (cMyBP-C) is a thick filament-associated protein of the sarcomere and a potential therapeutic target for treating contractile dysfunction in heart failure. Mimicking the structural dynamics of phosphorylated cMyBP-C by small-molecule drug binding could lead to therapies that modulate cMyBP-C conformational states, and thereby function, to improve contractility. We have developed a human cMyBP-C biosensor capable of detecting intramolecular structural changes due to phosphorylation and mutation. Using site-directed mutagenesis and time-resolved fluorescence resonance energy transfer (TR-FRET), we substituted cysteines in cMyBP-C N-terminal domains C0 through C2 (C0-C2) for thiol-reactive fluorescent probe labeling to examine C0-C2 structure. We identified a cysteine pair that upon donor-acceptor labeling reports phosphorylation-sensitive structural changes between the C1 domain and the tri-helix bundle of the M-domain that links C1 to C2. Phosphorylation reduced FRET efficiency by ~18%, corresponding to a ~11% increase in the distance between probes and a ~30% increase in disorder between them. The magnitude and precision of phosphorylation-mediated TR-FRET changes, as quantified by the Z'-factor, demonstrate the assay's potential for structure-based high-throughput screening of compounds for cMyBP-C-targeted therapies to improve cardiac performance in heart failure. Additionally, by probing C1's spatial positioning relative to the tri-helix bundle, these findings provide new molecular insight into the structural dynamics of phosphoregulation as well as mutations in cMyBP-C. Biosensor sensitivity to disease-relevant mutations in C0-C2 was demonstrated by examination of the hypertrophic cardiomyopathy mutation R282W. The results presented here support a screening platform to identify small molecules that regulate N-terminal cMyBP-C conformational states.

Original languageEnglish (US)
Pages (from-to)116-126
Number of pages11
JournalJournal of Molecular and Cellular Cardiology
StatePublished - May 2022


  • Biosensor
  • Cardiac myosin-binding protein C (cMyBP-C)
  • Fluorescence lifetime
  • High-throughput screening (HTS)
  • Phosphorylation
  • Protein kinase A (PKA)
  • Time-resolved fluorescence resonance energy transfer (TR-FRET)

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine


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