My research goal is to study the molecular mechanism of muscle contraction, with an emphasis on hypertrophic cardiomyopathy (HCM) and heart failure (HF). I am using multidisciplinary approaches such as biochemistry (steady state and transient kinetics), molecular biology (site-directed mutagenesis of muscle proteins to introduce probes), muscle mechanics, and biophysics (spectroscopy) to solve fundamental problems in the mechanism of muscle contractility. I use fluorescence resonance energy transfer (FRET), and electron paramagnetic resonance (EPR) spectroscopies to study the myosin-actin interaction and the lever arm rotation in solution and in muscle fibers, and to determine how this is affected by HCM mutations in myosin and its light chains. I am also developing fluorescent myosin biosensors for high-throughput screening assays for small compounds. This led to studying the mechanism of compounds on the kinetics of the actin-myosin interaction (Roopnarine and Thomas, 2021).
The intrigue of possibly discovering compounds as a therapy for cardiac dysfunction is a strong impetus to further explore the high throughput screening (HTS) of compound libraries for discovering small molecules for heart failure therapy. Fortuitously, Dr. David Thomas was developing state-of-the-art technology for FRET HTS in live cells using biosensors to identify hit compounds for alleviating heart failure due to dysfunction of cardiac SERCA and its regulatory proteins. I collaborated with the teams of Dr. Thomas, Dr. Cornea, and Dr. Aldrich to study HTS for allosteric activators of SERCA (Bidwell et al., 2022) that discovered a range of activators, some showed isoform specificity for either skeletal or cardiac SERCA. I am also investigating the relationship that SERCA had with its regulator proteins, phospholamban (PLB, an inhibitor) and a dwarf open reading frame (DWORF, an activator) peptide to show that there is opposing effects of the regulators that are dependent on [Ca2+] (Rustad et al, 2023). The discovery of small molecules as allosteric modulators of SERCA using FRET HTS is ongoing.
Rustad, MD*, O Roopnarine*, A Li, PD Martin, RL Cornea, and DD Thomas. 2023. Interaction of DWORF with SERCA and PLB determined by EPR. *Equal contributions. Biochem Biophys Res Commun. 645:97-102. PMID: 36682333 DOI: 10.1016/j.bbrc.2023.01.041
Bidwell, PA, SL Yuen, J Li, K Berg, RT Rebbeck, CC Aldrich, O Roopnarine, RL Cornea, and DD Thomas. 2022. A large-scale high-throughput screen for modulators of SERCA activity. Biomolecules 12:1789. PMID: 36551215 PMCID: PMC9776381 DOI: 10.3390/biom12121789
O. Roopnarine and D.D. Thomas. 2021. Mechanistic analysis of actin-binding compounds that affect the kinetics of cardiac myosin-actin interaction. J. of Biol. Chem. 2021. 296:100471. PMCID: PMC8063737. PMID: 33639160. DOI: 10.1016/j.jbc.2021.100471
J. A., Rohde, O. Roopnarine, D. D. Thomas, J. M. Muretta. 2018. Mavacamten stabilizes an autoinhibited state of two-headed cardiac myosin. Proc Natl Acad Sci U S A.115(32):E7486-E7494. PMID: 30018063
P. Guhathakurta, E. Prochniewicz, O. Roopnarine, J. A. Rohde, and D. D. Thomas. 2017. A Cardiomyopathy Mutation in the Myosin Essential Light Chain Alters the Structural Interaction with Actin. Biophys. J.113:91-100. PMID: 28700929
O. Roopnarine. 2003. Mechanical defects of muscle fibers with myosin light chain mutants that cause cardiomyopathy. Biophys. J., 84:2440-2449. PMID: 12668451
O. Roopnarine. 2002. Familial Hypertrophic Cardiomyopathic myosin mutations that affect the actin-myosin interaction. In Molecular Interactions of Actin. Actin-Myosin Interaction and Actin-Based Regulation. Springer-Verlag Berlin Heidelberg, Germany. Results Probl. Cell. Differ. 36:75-86. PMID: 11892286
D. D. Thomas, E. Prochniewicz and O. Roopnarine. 2002. Changes in Actin and Myosin Structural Dynamics Due to Their Weak and Strong Interactions. In Molecular Interactions of Actin. Actin-Myosin Interaction and Actin-Based Regulation. Springer-Verlag Berlin Heidelberg, Germany. Results Probl. Cell. Differ. 36:7-19. PMID: 11892285
D. D. Thomas and O. Roopnarine. 2002. An overview of the actomyosin interaction. In Molecular Interactions of Actin. Actin-Myosin Interaction and Actin-Based Regulation. Springer-Verlag Berlin Heidelberg, Germany. Results Probl. Cell. Differ. 36:1-5.
O. Roopnarine and L.A. Leinwand. 1998. Functional analysis of myosin mutations that cause familial hypertrophic cardiomyopathy. Biophys. J., 75:3023-3030. PMID: 9826622
O. Roopnarine, A.G. Szent-Györgyi, and D.D. Thomas. 1998. Microsecond rotational dynamics of spin-labeled myosin regulatory light chain induced by relaxation and contraction of scallop muscle. Biochemistry, 37:14428-14436. PMID: 9772169
O. Roopnarine and D.D. Thomas. 1996. Orientational dynamics of intermediate nucleotide states of indane dione spin-labeled myosin heads in skeletal muscle fibers. Biophys. J., 70:2795-2806. PMID: 8744317
O. Roopnarine and D.D. Thomas. 1995. Orientational dynamics of indane-dione spin-labeled myosin heads in relaxed and contracting skeletal muscle fibers. Biophys. J., 68:1461-1471. PMID: 7787032
O. Roopnarine, A.G. Szent-Györgyi, and D.D. Thomas. 1995. Saturation transfer electron paramagnetic resonance of spin-labeled myosin regulatory light chains in contracting muscle fibers. Biophys. J. 68:337s
Thomas, D.D., R. Ramachandran, O. Roopnarine, D.W. Hayden and E.M. Ostap. 1995. The mechanism of force generation in myosin, a disorder-to-order transition, coupled to internal structural changes. Biophys. J., 68:135s-141s. PMID: 7787056
O. Roopnarine and D.D. Thomas. 1994. A spin label that binds to myosin heads in muscle fibers with its principal axis parallel to the fiber axis. Biophys. J., 67:1634-1645. PMID: 7819495
O. Roopnarine, K. Hideg, and D.D. Thomas. 1993. Saturation Transfer EPR of an Indane-Dione Spin-Label: Calibration with Hemoglobin and Application to Myosin Rotational Dynamics. Biophys. J., 64:1896-1906. PMID: 8396449
P. James, A.K. Alrich, O. Roopnarine and J. Parker. 1989. Context specific misreading of phenylalanine codons. Molecular General Genetics 218:397-401. PMID: 2685541