Dynamics Imaging of Biomolecular Assemblies

 

Research

Single cells are the building blocks for all biological systems; yet they are inherently complex with intricate networks of dynamic biomolecular assemblies made up of proteins, coenzymes, ligands, DNA, RNA and lipids. In addition, these molecular assemblies are dynamically changing their sizes, conformations and intermolecular interactions in response to specific chemical, environmental or biological cues. In Heikal laboratory, we are using a multiparametric fluorescence microspectroscopy to investigate biomolecular events in both controlled environment and live cells/tissues under different pathophysiological conditions. This noninvasive and quantitative approach complements traditional biochemical techniques on purified biomolecules from cell lysates. Our interdisciplinary research interests include (but not limited to):Energy metabolism and mitochondrial anomalies, Biomimetic membranes, Immunoglobulin E receptor signaling, Protein dynamics and protein-protein interactions, Single molecule studies, Molecular crowding and Development of micro-spectroscopic and analytical techniques.

Below, we highlight some peer-reviewed publications that reflect our broad research interests.

A. Energy Metabolism and Mitochondria

  1. Heikal, A.A. A Multiparametric imaging of cellular coenzymes for monitoring metabolic and mitochondrial activities. In, “Annual Review in Fluorescence 2010”, Editor: Chris D.Geddes, Springer, 2011.

  2. Heikal, A.A. Intracellular coenzymes as natural biomarkers for metabolic activities and mitochondrial anomalies. Biomarkers in Medicine, 4(2): 241-263 (2010); Invited Review.

  3. Yu, Q. and A.A. Heikal. Two-photon autofluorescence dynamics imaging reveals sensitivity of intracellular NADH concentration and conformation to cell physiology at the single-cell level. Journal of Photochemistry and Photobiology (B): Biology, 95: 46–57 (2009); Press Release.

  4. Vishwasrao, H.D., A.A. Heikal, K.A. Kasischke, and W.W. Webb. Conformational dependence of intracellular NADH on metabolic state revealed by associated fluorescence anisotropy. J. Biol. Chem., 280:25119-25126 (2005); Press Release, Issue Cover and Paper of the Week.

  5. Huang, S., A.A. Heikal, and W.W. Webb. Two-photon fluorescence spectroscopy and microscopy on NAD(P)H and flavoprotein, Biophys. J., 82:2811-2825 (2002).

Mitochondrial Function (Heikal, Biomarkers in Medicine, 2010)

B. Biomimetic Membranes

  1. Heikal, A.A. A Multiparametric fluorescence approach for biomembrane studies. In, “Advances in Planar Lipid Bilayers and Liposomes”, Editor: Iglic A, Volume 13, Elsevier, Inc.; p. 169-197 (May 2011).

  2. Ariola, F.S., Z. Li, C. Cornejo, R. Bittman, and A.A. Heikal. Membrane fluidity and lipid order in ternary giant unilamellar vesicles using a new Bodipy-cholesterol derivative. Biophysical Journal, April Issue, 96(7), 26962708 (2009).

  3. Ariola, F.S., D.J. Mudaliar, R.P. Walvick, and A.A. Heikal. Dynamics imaging of lipid phases and lipid-marker interactions in model biomembranes. Phys. Chem. Chem. Phys., 8:4517-4529 (2006).

Phase Separation in GUVs Labeled with Bodipy-Cholesterol and DiI-C12 (Ariola et al. Biophys. J. 2009)

C. Immunoglobulin E Receptor Signaling

  1. Davey, A.M., K. Krise. E.D. Sheets, and A.A. Heikal. Molecular perspective of antigen-mediated mast cell signaling. J. Biol. Chem., 283:7117-7127 (2008); Press Release.

  2. Davey, A.M., R.P. Walvick, Y. Liu, A.A. Heikal, and E.D. Sheets. Membrane order and molecular dynamics associated with IgE receptor crosslinking in mast cells. Biophys. J., 92:343-355 (2007).

IgE Receptor Signaling Pathway (Davey et al, Biophys. J., 2007)

D. Intrinsically Fluorescent Proteins

  1. Liu, Y., H.-R. Kim, and A.A. Heikal. Structural basis of fluorescence fluctuation dynamics of green fluorescent proteins in acidic environments. J. Phys. Chem. B, 110:24138-24146 (2006).

  2. Hess, S.T.,E.D. Sheets, A. Wagenknecht-Wiesner, and A.A. Heikal. Quantitative analysis of the fluorescence properties of intrinsically fluorescent proteins in living cells. Biophys. J., 85:2566-2580 (2003). 

  3. Heikal, A.A., S.T. Hess, G.S. Baird, R.Y. Tsien, and W.W. Webb. Molecular spectroscopy and dynamics of intrinsically fluorescent proteins: coral red (dsRed) and yellow (Citrine). Proc. Natl. Acad. Sci. USA, 97:11996-12001 (2000).

E. Micro-spectroscopy & Technique Development

  1. Heikal, A.A. A Multiparametric fluorescence approach for biomembrane studies. In, “Advances in Planar Lipid Bilayers and Liposomes”, Editor: Iglic A, Volume 13, Elsevier, Inc.; p. 169-197 (May 2011).

  2. Heikal, A.A. Time-resolved fluorescence anisotropy and fluctuation correlation analysis of major histocompatibility complex class I proteins in fibroblast cells. Methods; In Press (2013). (DOI 10.1016/j.ymeth.2013.06.023).

  3. Yu, Q., M. Proia, and A.A. Heikal. Integrated biophotonics approach for noninvasive and multiscale studies of biomolecular and cellular biophysics. J. Biomed. Optics; July/August Issue, 13(4):0413151-14, (2008).