Incollection,
Quantitative Studies of the Effects of Cytoskeletal-Destabilizing Agents and Actin Mutations on the Dynamics of G1-Arrested S. cerevisea Mitochondria
Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)
Abstract
The cytoskeleton plays a central role to most cell behaviors, including the establishment of cell polarity, cell division and organelle re-distribution. It is known that control of the cytoskeleton involves cooperative structural and dynamical properties of hundreds of interacting proteins. In particular, the redistribution of mitochondria in the cytosol is thought to depend on the regulated assembly of actin filaments. In this work, we describe novel experimental studies of the spatio-temporal relaxations of mitochondria in the budding yeast Saccharomyces cerevisiae. We employ Fourier imaging correlation spectroscopy (FICS) 1-3, a fluorescence-based optical coherence measurement that monitors the fluctuations of a spatial Fourier component of the local mitochondrial filament density at an experimentally adjustable length scale 4, 5. From our measurements, we construct the intermediate scattering function for mitochondrial relaxation over the full range of length (0.5 2.6 micrometers) and time scales (0.1 200 seconds) necessary to characterize this system. From a comparison of the effects of microtubule (MT) and microfilament (MF) destabilizing agents, we find that MTs have no effect on mitochondrial dynamics, while MFs are strictly required. We further investigate the effects of genetic mutants of actin related proteins, including the actin-related protein complex Arp2/3. Arp2/3 is known to nucleate and to auto-catalyze actin filament assembly as a means to generate directional forces at intracellular membrane surfaces 6-8. Our results corroborate such an Arp2/3-dendritic-assembly mechanism, which has previously been implicated by genetic studies of yeast mitochondrial motility 9.
References:
1. Knowles, M.K., T.J. Grassman, and A.H. Marcus, Measurement of the dynamic structure function of fluorescently labeled complex fluids by Fourier imaging correlation spectroscopy. Phys. Rev. Lett., 2000. 85: p. 2837-2840.
2. Grassman, T.J., M.K. Knowles, and A.H. Marcus, Structure and dynamics of fluorescently labeled complex fluids by Fourier imaging correlation specroscopy. Phys. Rev. E, 2000. 62: p. 8245-8257.
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4. Knowles, M.K., M.G. Guenza, R. Capaldi, and A.H. Marcus, Cytoskeletal-assisted dynamics of the mitochondrial reticulum in living cells. Proc. Nat. Acad. Sci., 2002. 99: p. 14772-14777.
5. Margineantu, D., R.A. Capaldi, and A.H. Marcus, Dynamics of the mitochondrial reticulum in living cells using Fourier imaging correlation spectroscopy and digital video microscopy. Biophys. J., 2000. 79: p. 1833-1849 (journal cover aritlce).
6. Pollard, T.D., and G.G. Borisy, Cellular motility driven by assembly and disassembly of actin filaments. Cell, 2003. 112: p. 453-465.
7. Mogilner, A., and L. Edelstein-Keshet, Regulation of actin dynamics in rapidly moving cells: a quantitative analysis. Biophys. J., 2002. 83: p. 1238-1258.
8. Pantaloni, D., C. Le Clainche, and M.-F. Carlier, Mechanism of actin-based motility. Science, 2001. 292: p. 1502-1506.
9. Fehrenbacher, K.L., H.-C. Yang, A.C. Gay, T.M. Huckaba, and L.A. Pon, Live cell imaging of mitochondrial movement along actin cables in budding yeast. Curr. Biol., 2004. 14: p. 1996-2004.
Tags
- actin
- cytoskeleton
- dynamics
- filament
- fluctuations
- fluorescence
- intracellular
- mitochondria
- motility
- statphys23
- topic-10
