Human cardiac myosin-binding protein C restricts actin structural dynamics in a cooperative and phosphorylation-sensitive manner
AffiliationUniv Arizona, Dept Cellular & Mol Med
cardiac myosin–binding protein C (cMyBP-C)
protein kinase A (PKA)
MetadataShow full item record
CitationBunch, T. A., Kanassatega, R. S., Lepak, V. C., & Colson, B. A. (2019). Human cardiac myosin–binding protein C restricts actin structural dynamics in a cooperative and phosphorylation-sensitive manner. Journal of Biological Chemistry, 294(44), 16228-16240.
JournalJOURNAL OF BIOLOGICAL CHEMISTRY
Rights© 2019 Bunch et al. Author's Choice—Final version open access under the terms of the Creative Commons CC-BY license.
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AbstractCardiac myosin-binding protein C (cMyBP-C) is a thick filament-associated protein that influences actin-myosin interactions. cMyBP-C alters myofilament structure and contractile properties in a protein kinase A (PKA) phosphorylation-dependent manner. To determine the effects of cMyBP-C and its phosphorylation on the microsecond rotational dynamics of actin filaments, we attached a phosphorescent probe to F-actin at Cys-374 and performed transient phosphorescence anisotropy (TPA) experiments. Binding of cMyBP-C N-terminal domains (C0-C2) to labeled F-actin reduced rotational flexibility by 20-25°, indicated by increased final anisotropy of the TPA decay. The effects of C0-C2 on actin TPA were highly cooperative (n = ∼8), suggesting that the cMyBP-C N terminus impacts the rotational dynamics of actin spanning seven monomers (i.e. the length of tropomyosin). PKA-mediated phosphorylation of C0-C2 eliminated the cooperative effects on actin flexibility and modestly increased actin rotational rates. Effects of Ser to Asp phosphomimetic substitutions in the M-domain of C0-C2 on actin dynamics only partially recapitulated the phosphorylation effects. C0-C1 (lacking M-domain/C2) similarly exhibited reduced cooperativity, but not as reduced as by phosphorylated C0-C2. These results suggest an important regulatory role of the M-domain in cMyBP-C effects on actin structural dynamics. In contrast, phosphomimetic substitution of the glycogen synthase kinase (GSK3β) site in the Pro/Ala-rich linker of C0-C2 did not significantly affect the TPA results. We conclude that cMyBP-C binding and PKA-mediated phosphorylation can modulate actin dynamics. We propose that these N-terminal cMyBP-C-induced changes in actin dynamics help explain the functional effects of cMyBP-C phosphorylation on actin-myosin interactions.
NoteOpen access article.
VersionFinal published version
SponsorsNational Institutes of HealthUnited States Department of Health & Human ServicesNational Institutes of Health (NIH) - USA [R00 HL122397, R01 HL141564]
- Cardiac myosin binding protein-C restricts intrafilament torsional dynamics of actin in a phosphorylation-dependent manner.
- Authors: Colson BA, Rybakova IN, Prochniewicz E, Moss RL, Thomas DD
- Issue date: 2012 Dec 11
- N-terminal extension in cardiac myosin-binding protein C regulates myofilament binding.
- Authors: Bunch TA, Lepak VC, Kanassatega RS, Colson BA
- Issue date: 2018 Dec
- Identification of novel protein kinase A phosphorylation sites in the M-domain of human and murine cardiac myosin binding protein-C using mass spectrometry analysis.
- Authors: Jia W, Shaffer JF, Harris SP, Leary JA
- Issue date: 2010 Apr 5
- C0 and C1 N-terminal Ig domains of myosin binding protein C exert different effects on thin filament activation.
- Authors: Harris SP, Belknap B, Van Sciver RE, White HD, Galkin VE
- Issue date: 2016 Feb 9
- Phosphorylation of cardiac myosin binding protein C releases myosin heads from the surface of cardiac thick filaments.
- Authors: Kensler RW, Craig R, Moss RL
- Issue date: 2017 Feb 21
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