Striated muscle contraction is regulated by Ca2+, which binds to the troponin (Tn) complex located on the thin filament. Ca2+-binding to TnC, one of the Tn components, triggers a series of structural change among the thin filament proteins, subsequently allowing the interaction of the thick and thin filaments. The regulation by Ca2+-activation of cardiac muscle is fine-tuned by covalent modification, such as phosphorylation of the myofilament proteins, including TnI and TnT. Using biochemical, biophysical and molecular biology methods, we are investigating how the Ca2+-binding to TnC activates the thin filament to initiate contraction and how this event is modified by covalent modification under the pathophysiological conditions.
Publications: Recent (since 2003) and Selected.
Kobayashi, T., Takagi, T., Konishi, K. and Cox, J. A . (1989) Amino Acid Sequence of Crayfish Troponin I. J. Biol. Chem. 264, 1551-1557.
Kobayashi, T., Takagi, T., Konishi, K. and Wnuk, W. (1989) Amino Acid Sequences of the Two Major Isoforms of Troponin C from Crayfish. J. Biol. Chem. 264, 18247-18259.
Kobayashi, T., Takagi, T., Konishi, K., Morimoto, S. and Ohtshuki, I . (1989) Amino Acid Sequence of Porcine Cardiac Muscle Troponin C. J. Biochem . 106, 55-59.
Kobayashi, T., Tao, T., Grabarek, Z., Gergely, J. and Collins, J. H. (1991) Cross-linking of Residue 57 in the Regulatory Domain of a Mutant Rabbit Skeletal Muscle Troponin C to the Inhibitory Region of Troponin I. J. Biol. Chem . 266, 13746-13751.
Kobayashi, T., Tao, T., Gergely, J. and Collins, J. H. (1994) Structure of the Troponin Complex: Implications of the Photocross-Linking of Troponin I to Troponin C Thiol Mutants. J. Biol. Chem . 269, 5725-5729.
Kobayashi, T., Grabarek, Z., Gergely, J. and Collins, J. H. (1995) Extensive Interactions Between Troponins C and I: Zero-Length Cross-Linking of Troponin I and Acetylated Troponin C. Biochemistry 34, 10946-10952.
Kobayashi, T . (1996) Nonvertebrate Troponin. In Guidebook on Calcium Binding-Proteins (Celio, M. ed.) pp.71-73, Oxford University Press.
Takeda, S., Kobayashi, T., Taniguchi, H., Hayashi, H. and Maéda, Y. (1997) Structural and Functional Domains of the Troponin Complex Revealed by Limited Digestion . Eur. J. Biochem . 246, 611-617.
Miki, M., Kobayashi, T., Kimura, H., Hagiwara, A., Hai, H. and Maéda, Y. (1998) Ca2+-Induced Distance Change between Points on Actin and Troponin in Skeletal Muscle Thin Filaments Estimated by Fluorescence Energy Transfer Spectroscopy. J. Biochem . 123, 324-331.
Kobayashi, T., Zhao, X., Wade, R. and Collins, J. H. (1999) Involvement of Conserved, Acidic Residues in the N-terminal Domain of Troponin C in Calcium-Dependent Regulation. Biochemistry 38, 5386-5391.
Kobayashi, T., Kobayashi, M., Gryczynski, Z., Lakowicz, J. R. and Collins, J. H. (2000) Inhibitory Region of Troponin I: Ca2+-Dependent Structural and Environmental Changes in the Troponin-Tropomyosin Complex and in Reconstituted Thin Filaments. Biochemistry 39, 86-91.
Kobayashi, T., Kobayashi, M. and Collins, J. H . (2001) Ca2+-Dependent, Myosin Subfragment 1-Induced Proximity Changes between Actin and the Inhibitory Region of Troponin I. Biochim. Biophys. Acta 1549, 148-154.
Burkart, E. M., Sumandea, M. P., Kobayashi, T., Nili, M., Martin, A. F., Homsher, E. and Solaro, R. J. (2003) Phosphorylation or Glutamic Acid Substitution at Protein Kinase C Sites on Cardiac Troponin I Differentially Depress Myofilament Tension and Shortening Velocity. J. Biol. Chem . 278, 11265-11272.
Sumandea, M. P., Pyle, W. G., Kobayashi, T., de Tombe, P. P. and Solaro, R. J. (2003) Identification of a Functionally Critical PKC Phosphorylation Residue of Cardiac Troponin T. J. Biol. Chem . 278, 35135-35144.
Yang, X., Wu, H., Kobayashi, T., Solaro, R. J., and van Breemen, R. B. (2004) Enhanced Ionization of Phosphorylated Peptides During MALDI-TOF Mass Spectrometry. Anal. Chem . 76, 1532-1536.
Kobayashi, T., Dong, W.-J., Burkart, E. M., Cheung, H. C., and Solaro, R. J . (2004) Effects of Protein Kinase C Dependent Phosphorylation and a Familial Hypertrophic Cardiomyopathy-Related Mutation of Cardiac Troponin I on Structural Transition of Troponin C and Myofilament Activation. Biochemistry 43, 5996-6004.
Sumandea, M. P., Burkart, E. M., Kobayashi, T., de Tombe, P. P., and Solaro, R. J. (2004) Molecular and Integrated biology of thin filament protein phosphorylation in heart muscle. Ann. NY Acad. Sci .USA , 1014, 39-52.
Kobayashi, T., Yang, X., Walker, L. A., van Breemen, R. B., and Solaro, R. J. (2005) A Non-Equilubrium Isoelectric Focusing Method to Determine States of Phosphorylation of Cardiac Troponin I: Identification of Ser23 and Ser24 as Significant Sites of Phosphorylation by Protein Kinase C. J. Mol. Cell. Cardio l. 38, 213-218.
Kobayashi, T., and Solaro, R. J. (2005) Calcium, Thin Filaments, and the Integrative Biology of Cardiac Contractility. Annu. Rev. Physiol . 67, 39-67.
Vahebi, S., Kobayashi, T., Warren, C. M., de Tombe, P. P., and Solaro, R. J. (2005) Functional Effects of Rho-kinase (ROCK-II) Dependent Phosphorylation of Specific Sites on Cardiac Troponin. Circ. Res . 96, 740-747.
Kobayashi, T., and Solaro, R. J. (2006) Increased Ca 2+ -affinity of Cardiac Thin Filaments Reconstituted with Cardiomyopathy-related Mutant Cardiac Troponin I. J. Biol. Chem. 281, 13471-13477.
Belin, R. J., Sumandea, M. P., Kobayashi, T., Walker, L. A., Rundell, V. L., Yuzahakova, M., Ruch, S. H. Geenen, D. L., Solaro, R. J., and de Tombe, P. P. (2006) Myofilament Dysfunction in Rat Experimental Left Ventricular Hypertrophy and Congestive Heart Failure. Am. J. Physiol. Heart and Circ. Physiol . 291, H2344-2353.
Engel, P. L., Kobayashi, T., Biesiadecki, B., Davis, J., Tikunova, S., Wu, S., and Solaro, R. J. (2007) Identification of a Region of Troponin I Important in Signaling Cross-Bridge Dependent Activation of Cardiac Myofilaments. J. Biol. Chem . 282, 183-193.
Davis, J. P., Norman, C., Kobayashi, T., Solaro, R. J., Swartz, D. R., and Tikunova, S. B. (2007) Effects of Thin and Thick Filament Proteins on Calcium Binding and Exchange with Cardiac Troponin C. Biophys. J. 92, 3195-3206.
Biesiadecki, B. J., Kobayashi, T., Walker, J. S., Solaro, R. J., and de Tombe, P. P. (2007) The Troponin C G159D Mutation Blunts Myofilament Desensitization Induced by Troponin I Ser-23/24 Phosphorylation. Circ. Res . 100, 1486-1493.
Mathur, M., Kobayashi, T., and Chalovich, J. M. (2007) Negative Charges at Protein Kinase C Sites of Troponin I Stabilize the Inactive State of Actin. Biophys J. In press.
send email to: tkoba@uic.edu
08/30/07