Hypertrophic cardiomyopathy mutations at the folded-back sequestered β-cardiac myosin S1-S2 and S1-S1 interfaces release sequestered heads and increase myosin enzymatic activity

AbstractHypertrophic cardiomyopathy (HCM) affects 1 in 500 people and leads to hyper-contractility of the heart. Nearly 40 percent of HCM-causing mutations are found in human β-cardiac myosin. Previous studies looking at the effect of HCM mutations on the force, velocity and ATPase activity of the catalytic domain of human β-cardiac myosin have not shown clear trends leading to hypercontractility at the molecular scale. Here we present functional data showing that four separate HCM mutations located at the myosin head-tail (R249Q, H251N) and head-head (D382Y, R719W) interfaces of a folded-back sequestered state referred to as the interacting heads motif lead to a significant increase in the number of heads functionally accessible for interaction with actin. These results provide evidence that HCM mutations can modulate myosin activity by disrupting intramolecular interactions within the proposed sequestered state, thereby leading to hypercontractility at the molecular level.

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Hypertrophic Cardiomyopathy Mutations Disrupt Human Beta Cardiac Myosin Intramolecular Interactions Leading to Increased Myosin Activity

Biophysical Journal ◽

10.1016/j.bpj.2017.11.783 ◽

2018 ◽

Vol 114 (3) ◽

pp. 139a

Author(s):

Arjun S. Adhikari ◽

Darshan V. Trivedi ◽

Saswata S. Sarkar ◽

Kathleen M. Ruppel ◽

Spudich A. James

Keyword(s):

Hypertrophic Cardiomyopathy ◽

Intramolecular Interactions ◽

Cardiac Myosin ◽

Cardiomyopathy Mutations

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Erratum: Micro-exons of the cardiac myosin binding protein C gene: flanking introns contain a disproportionately large number of hypertrophic cardiomyopathy mutations

European Journal of Human Genetics ◽

10.1038/ejhg.2008.80 ◽

2008 ◽

Vol 16 (8) ◽

pp. 1026-1026

Author(s):

Rune Frank-Hansen ◽

Stephen P Page ◽

Petros Syrris ◽

William J McKenna ◽

Michael Christiansen ◽

...

Keyword(s):

Hypertrophic Cardiomyopathy ◽

Protein C ◽

Binding Protein ◽

Cardiac Myosin ◽

Myosin Binding Protein ◽

Myosin Binding Protein C ◽

Myosin Binding ◽

Cardiomyopathy Mutations

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Cardiac myosin-binding protein C: hypertrophic cardiomyopathy mutations and structure–function relationships

Pflügers Archiv - European Journal of Physiology ◽

10.1007/s00424-013-1400-3 ◽

2013 ◽

Vol 466 (2) ◽

pp. 201-206 ◽

Cited By ~ 13

Author(s):

Vasco Sequeira ◽

E. Rosalie Witjas-Paalberends ◽

Diederik W. D. Kuster ◽

Jolanda van der Velden

Keyword(s):

Hypertrophic Cardiomyopathy ◽

Structure Function ◽

Protein C ◽

Binding Protein ◽

Cardiac Myosin ◽

Myosin Binding Protein ◽

Myosin Binding Protein C ◽

Myosin Binding ◽

Cardiomyopathy Mutations

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Mutations in the catalytic domain of human β-cardiac myosin that cause early onset hypertrophic cardiomyopathy significantly increase the fundamental parameters that determine ensemble force and velocity

10.1101/067066 ◽

2016 ◽

Cited By ~ 1

Author(s):

Arjun S. Adhikari ◽

Kristina B. Kooiker ◽

Chao Liu ◽

Saswata S. Sarkar ◽

Daniel Bernstein ◽

...

Keyword(s):

Hypertrophic Cardiomyopathy ◽

Single Molecule ◽

Early Onset ◽

Catalytic Domain ◽

Cardiovascular Disorder ◽

Cardiac Myosin ◽

Binding Studies ◽

Fundamental Parameters ◽

Biomechanical Parameters ◽

Myosin Motors

AbstractHypertrophic cardiomyopathy (HCM) is a heritable cardiovascular disorder that affects 1 in 500 people. In infants it can be particularly severe and it is the leading cause of sudden cardiac death in pediatric populations. A high percentage of HCM is attributed to mutations in β-cardiac myosin, the motor protein that powers ventricular contraction. This study reports how two mutations that cause early-onset HCM, D239N and H251N, affect the mechanical output of human β-cardiac myosin at the molecular level. We observe extremely large increases (25% – 95%) in the actin gliding velocity, single molecule intrinsic force, and ATPase activity of the two mutant myosin motors compared to wild type myosin. In contrast to previous studies of HCM-causing mutations in human β-cardiac myosin, these mutations were striking in that they caused changes in biomechanical parameters that were both greater in magnitude and more uniformly consistent with a hyper-contractile phenotype. In addition, S1-S2 binding studies revealed a significant decrease in affinity of the H251N motor for S2, suggesting that this mutation may further increase hyper-contractility by releasing active motors from a sequestered state. This report shows, for the first time, a clear and significant gain in function for all tested molecular biomechanical parameters due to HCM mutations in human β-cardiac myosin.

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The hypertrophic cardiomyopathy mutations R403Q and R663H increase the number of myosin heads available to interact with actin

Science Advances ◽

10.1126/sciadv.aax0069 ◽

2020 ◽

Vol 6 (14) ◽

pp. eaax0069 ◽

Cited By ~ 3

Author(s):

Saswata S. Sarkar ◽

Darshan V. Trivedi ◽

Makenna M. Morck ◽

Arjun S. Adhikari ◽

Shaik N. Pasha ◽

...

Keyword(s):

Hypertrophic Cardiomyopathy ◽

Cardiac Myosin ◽

Similar Reduction ◽

Enzymatic Assays ◽

Single Turnover ◽

Myosin Binding Protein ◽

Myosin Binding Protein C ◽

Contractile Parameters ◽

Myosin Binding ◽

Cardiomyopathy Mutations

Hypertrophic cardiomyopathy (HCM) mutations in β-cardiac myosin and myosin binding protein-C (MyBP-C) lead to hypercontractility of the heart, an early hallmark of HCM. We show that hypercontractility caused by the HCM-causing mutation R663H cannot be explained by changes in fundamental myosin contractile parameters, much like the HCM-causing mutation R403Q. Using enzymatic assays with purified human β-cardiac myosin, we provide evidence that both mutations cause hypercontractility by increasing the number of functionally accessible myosin heads. We also demonstrate that the myosin mutation R403Q, but not R663H, ablates the binding of myosin with the C0-C7 fragment of MyBP-C. Furthermore, addition of C0-C7 decreases the wild-type myosin basal ATPase single turnover rate, while the mutants do not show a similar reduction. These data suggest that a primary mechanism of action for these mutations is to increase the number of myosin heads functionally available for interaction with actin, which could contribute to hypercontractility.

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Early-Onset Hypertrophic Cardiomyopathy Mutations Significantly Increase the Velocity, Force, and Actin-Activated ATPase Activity of Human β-Cardiac Myosin

Cell Reports ◽

10.1016/j.celrep.2016.11.040 ◽

2016 ◽

Vol 17 (11) ◽

pp. 2857-2864 ◽

Cited By ~ 37

Author(s):

Arjun S. Adhikari ◽

Kristina B. Kooiker ◽

Saswata S. Sarkar ◽

Chao Liu ◽

Daniel Bernstein ◽

...

Keyword(s):

Hypertrophic Cardiomyopathy ◽

Atpase Activity ◽

Early Onset ◽

Cardiac Myosin ◽

Cardiomyopathy Mutations

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β-Cardiac myosin hypertrophic cardiomyopathy mutations release sequestered heads and increase enzymatic activity

Nature Communications ◽

10.1038/s41467-019-10555-9 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 6

Author(s):

Arjun S. Adhikari ◽

Darshan V. Trivedi ◽

Saswata S. Sarkar ◽

Dan Song ◽

Kristina B. Kooiker ◽

...

Keyword(s):

Hypertrophic Cardiomyopathy ◽

Enzymatic Activity ◽

Cardiac Myosin ◽

Cardiomyopathy Mutations

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The molecular basis of hypercontractility caused by the hypertrophic cardiomyopathy mutations R403Q and R663H

10.1101/543413 ◽

2019 ◽

Cited By ~ 2

Author(s):

Saswata S. Sarkar ◽

Darshan V. Trivedi ◽

Makenna M. Morck ◽

Arjun S. Adhikari ◽

Shaik N. Pasha ◽

...

Keyword(s):

Hypertrophic Cardiomyopathy ◽

Protein C ◽

Binding Protein ◽

Cardiac Myosin ◽

Thin Filaments ◽

Fundamental Parameters ◽

Myosin Binding Protein ◽

Myosin Binding Protein C ◽

Force Velocity ◽

Myosin Binding

AbstractHypertrophic cardiomyopathy (HCM) mutations in ß-cardiac myosin and myosin binding protein-C (MyBP-C) cause hypercontractility of the heart. We show that hypercontractility caused by the HCM myosin mutation R663H cannot be explained by changes in the fundamental parameters such as actin-activated ATPase, intrinsic force, velocity of pure actin or regulated thin filaments, or the pCa50 of the velocity of regulated thin filaments. The same conclusion was made earlier for the HCM myosin mutation R403Q (Nag et al. 2015). Using enzymatic assays for the number of functionally-available heads in purified human ß-cardiac myosin preparations, we provide evidence that both R403Q and R663H HCM myosin mutations cause hypercontractility by increasing the number of functionally-accessible myosin heads. We also demonstrate that the myosin mutation R403Q, but not R663H, ablates the binding of myosin with the C0-C7 fragment of myosin binding protein-C.

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