Ensemble force changes that result from human cardiac myosin mutations and a small-molecule effector.
Cardiomyopathies due to mutations in human β-cardiac myosin are a significant cause of heart failure, sudden death, and arrhythmia. To understand the underlying molecular basis of changes in the contractile system's force production due to such mutations and search for potential drugs that restore force generation, an in vitro assay is necessary to evaluate cardiac myosin's ensemble force using purified proteins. Here, we characterize the ensemble force of human α- and β-cardiac myosin isoforms and those of β-cardiac myosins carrying left ventricular non-compaction (M531R) and dilated cardiomyopathy (S532P) mutations using a utrophin-based loaded in vitro motility assay and new filament-tracking software. Our results show that human α- and β-cardiac myosin, as well as the mutants, show opposite mechanical and enzymatic phenotypes with respect to each other. We also show that omecamtiv mecarbil, a previously discovered cardiac-specific myosin activator, increases β-cardiac myosin force generation.
Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.
Tural
T
Aksel
Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA; Cancer Biology Program, Stanford University School of Medicine, Stanford, CA 94305, USA.
Elizabeth
E
Choe Yu
Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA.
Shirley
S
Sutton
Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Pediatrics (Cardiology), Stanford University School of Medicine, Stanford, CA 94305, USA. Electronic address: kruppel@stanford.edu.
Kathleen M
KM
Ruppel
Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA. Electronic address: jspudich@stanford.edu.
James A
JA
Spudich
D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001696:Biomechanical Phenomena; D009202:Cardiomyopathies / Q000235:genetics; D002417:Cattle; D006801:Humans; D051379:Mice; D008954:Models, Biological; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics*; D054852:Small Molecule Libraries / Q000494:pharmacology*; D012984:Software; D013223:Statistics as Topic; D014508:Urea / Q000031:analogs & derivatives / Q000494:pharmacology; D049411:Utrophin / Q000378:metabolism; D024723:Ventricular Myosins / Q000235:genetics*
D000199:Actins; D054852:Small Molecule Libraries; D049411:Utrophin; C547293:omecamtiv mecarbil; D014508:Urea; D000251:Adenosine Triphosphatases; D024723:Ventricular Myosins