All Publications


  • Molecular Mechanisms and Cellular Models of Hypertrophic Cardiomyopathy: Insights from a Surprising Mutation Vander Roest, A. S., Liu, C., Kooiker, K. B., Morck, M. M., Pruitt, B., Campbell, K. S., Ruppel, K., Spudich, J. A., Bernstein, D. CELL PRESS. 2021: 253A
  • The hypertrophic cardiomyopathy mutations R403Q and R663H increase the number of myosin heads available to interact with actin SCIENCE ADVANCES Sarkar, S. S., Trivedi, D., Morck, M. M., Adhikari, A. S., Pasha, S. N., Ruppel, K. M., Spudich, J. A. 2020; 6 (14): eaax0069

    Abstract

    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.

    View details for DOI 10.1126/sciadv.aax0069

    View details for Web of Science ID 000523302400002

    View details for PubMedID 32284968

    View details for PubMedCentralID PMC7124958

  • Uncovering the Molecular and Structural Basis of Hypertrophic Cardiomyopathy-Causing Mutations in Myosin and Myosin Binding Protein-C Nandwani, N., Trivedi, D. V., Sarkar, S. S., Morck, M., Ruppel, K., Spudich, J. A. CELL PRESS. 2020: 435A
  • On the Functional Assessment of Hypertrophic Cardiomyopathy-Causing Mutations in Human beta-Cardiac Myosin and the Role of Myosin Binding Protein-C Trivedi, D. V., Sarkar, S. S., Adhikari, A. S., Morck, M. M., Kooiker, K. B., Bernstein, D., Ruppel, K. M., Spudich, J. A. CELL PRESS. 2019: 466A–467A
  • Deciphering the super relaxed state of human beta-cardiac myosin and the mode of action of mavacamten from myosin molecules to muscle fibers PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Anderson, R. L., Trivedi, D. V., Sarkar, S. S., Henze, M., Ma, W., Gong, H., Rogers, C. S., Gorham, J. M., Wong, F. L., Morck, M. M., Seidman, J. G., Ruppel, K. M., Irving, T. C., Cooke, R., Green, E. M., Spudich, J. A. 2018; 115 (35): EB143–EB152

    Abstract

    Mutations in β-cardiac myosin, the predominant motor protein for human heart contraction, can alter power output and cause cardiomyopathy. However, measurements of the intrinsic force, velocity, and ATPase activity of myosin have not provided a consistent mechanism to link mutations to muscle pathology. An alternative model posits that mutations in myosin affect the stability of a sequestered, super relaxed state (SRX) of the protein with very slow ATP hydrolysis and thereby change the number of myosin heads accessible to actin. Here we show that purified human β-cardiac myosin exists partly in an SRX and may in part correspond to a folded-back conformation of myosin heads observed in muscle fibers around the thick filament backbone. Mutations that cause hypertrophic cardiomyopathy destabilize this state, while the small molecule mavacamten promotes it. These findings provide a biochemical and structural link between the genetics and physiology of cardiomyopathy with implications for therapeutic strategies.

    View details for PubMedID 30104387

  • Impact of Hypertrophic Cardiomyopathy Mutations and the Role of Myosin Binding Protein-C on the Sequestered State of Myosin Trivedi, D. V., Sarkar, S. S., Morck, M. M., Adhikari, A. A., Ruppel, K. M., Spudich, J. A. CELL PRESS. 2018: 317A
  • A Molecular Approach to Understand the Super-Relaxed State of Myosin Observed in Cardiac Muscle Sarkar, S. S., Trivedi, D. V., Morck, M. M., Adhikari, A. S., Ruppel, K. M., Spudich, J. A. CELL PRESS. 2018: 141A
  • Recurrent RNA motifs as scaffolds for genetically encodable small-molecule biosensors NATURE CHEMICAL BIOLOGY Porter, E. B., Polaski, J. T., Morck, M. M., Batey, R. T. 2017; 13 (3): 295-?

    Abstract

    Allosteric RNA devices are increasingly being viewed as important tools capable of monitoring enzyme evolution, optimizing engineered metabolic pathways, facilitating gene discovery and regulators of nucleic acid-based therapeutics. A key bottleneck in the development of these platforms is the availability of small-molecule-binding RNA aptamers that robustly function in the cellular environment. Although aptamers can be raised against nearly any desired target through in vitro selection, many cannot easily be integrated into devices or do not reliably function in a cellular context. Here, we describe a new approach using secondary- and tertiary-structural scaffolds derived from biologically active riboswitches and small ribozymes. When applied to the neurotransmitter precursors 5-hydroxytryptophan and 3,4-dihydroxyphenylalanine, this approach yielded easily identifiable and characterizable aptamers predisposed for coupling to readout domains to allow engineering of nucleic acid-sensory devices that function in vitro and in the cellular context.

    View details for DOI 10.1038/NCHEMBIO.2278

    View details for Web of Science ID 000394431500013

    View details for PubMedID 28092358