A molecular trajectory of α-actinin activation.

The mechanisms by which living cells respond to mechanical stimuli are not yet fully understood. It has been suggested that mechanosensing proteins play an important role in mechanotransduction because their binding affinities are directly affected by the external stress. α-Actinin is an actin cross-linker and may act as a mechanosensor in adhesion sites. Its interaction with vinculin is suggested to be mechanically regulated. In this study, the free energy of activation is explored using the umbrella sampling method. An activation trajectory is generated in which α-actinin's vinculin-binding site swings out of the rod domain, leading to approximately an 8 kcal/mol free energy release. The activation trajectory reveals several local and global conformational changes along the activation pathway accompanied by the breakage of a number of key interactions stabilizing the inhibited structure. These results may shed light on the role of α-actinin in cellular mechanotransduction and focal adhesion formation.

[1]  Javad Golji,et al.  A molecular dynamics investigation of vinculin activation. , 2010, Biophysical journal.

[2]  P. Jones,et al.  The structure and function of alpha-actinin. , 1987, Biochemical Society transactions.

[3]  W. L. Jorgensen,et al.  Comparison of simple potential functions for simulating liquid water , 1983 .

[4]  Viola Vogel,et al.  Cell fate regulation by coupling mechanical cycles to biochemical signaling pathways. , 2009, Current opinion in cell biology.

[5]  Michael P. Sheetz,et al.  Stretching Single Talin Rod Molecules Activates Vinculin Binding , 2009, Science.

[6]  J J Otto,et al.  Actin-bundling proteins. , 1994, Current opinion in cell biology.

[7]  Martin A. Schwartz,et al.  The Force Is with Us , 2009, Science.

[8]  Daniel Nietlispach,et al.  The Vinculin Binding Sites of Talin and α-Actinin Are Sufficient to Activate Vinculin* , 2006, Journal of Biological Chemistry.

[9]  Hui Chen,et al.  Coincidence of Actin Filaments and Talin Is Required to Activate Vinculin* , 2006, Journal of Biological Chemistry.

[10]  T. Darden,et al.  Particle mesh Ewald: An N⋅log(N) method for Ewald sums in large systems , 1993 .

[11]  M. Sheetz,et al.  Local force and geometry sensing regulate cell functions , 2006, Nature Reviews Molecular Cell Biology.

[12]  O. Carpén,et al.  Alpha-actinin revisited: a fresh look at an old player. , 2004, Cell motility and the cytoskeleton.

[13]  R. Swendsen,et al.  THE weighted histogram analysis method for free‐energy calculations on biomolecules. I. The method , 1992 .

[14]  Javad Golji,et al.  Vinculin activation is necessary for complete talin binding. , 2011, Biophysical journal.

[15]  M. Parrinello,et al.  Polymorphic transitions in single crystals: A new molecular dynamics method , 1981 .

[16]  KumarShankar,et al.  The weighted histogram analysis method for free-energy calculations on biomolecules. I , 1992 .

[17]  Hoover,et al.  Canonical dynamics: Equilibrium phase-space distributions. , 1985, Physical review. A, General physics.

[18]  Gerard Bricogne,et al.  Crystal structure of human vinculin. , 2004, Structure.

[19]  Roger D Kamm,et al.  A microfluidic system with optical laser tweezers to study mechanotransduction and focal adhesion recruitment. , 2011, Lab on a chip.

[20]  J. Feramisco,et al.  Non-muscle α-actinins are calcium-sensitive actin-binding proteins , 1981, Nature.

[21]  Constantina Bakolitsa,et al.  Structural basis for vinculin activation at sites of cell adhesion , 2004, Nature.

[22]  Pere Roca-Cusachs,et al.  Stretchy proteins on stretchy substrates: the important elements of integrin-mediated rigidity sensing. , 2010, Developmental cell.

[23]  S. Lowen.  The Biophysical Journal , 1960, Nature.

[24]  Roger D Kamm,et al.  Force-induced activation of talin and its possible role in focal adhesion mechanotransduction. , 2007, Journal of biomechanics.

[25]  Clemens Vonrhein,et al.  Structural Dynamics of α-Actinin-Vinculin Interactions , 2005, Molecular and Cellular Biology.

[26]  K Schulten,et al.  VMD: visual molecular dynamics. , 1996, Journal of molecular graphics.

[27]  Jorge Nocedal,et al.  A Limited Memory Algorithm for Bound Constrained Optimization , 1995, SIAM J. Sci. Comput..

[28]  A. Blanchard,et al.  The structure and function of α-actinin , 1987, Journal of Muscle Research & Cell Motility.

[29]  S. Gunst,et al.  Activation of Vinculin Induced by Cholinergic Stimulation Regulates Contraction of Tracheal Smooth Muscle Tissue* , 2010, The Journal of Biological Chemistry.

[30]  Mohammad R. K. Mofrad,et al.  Rheology of the Cytoskeleton , 2009 .

[31]  Gerrit Groenhof,et al.  GROMACS: Fast, flexible, and free , 2005, J. Comput. Chem..

[32]  David R Critchley,et al.  The structure and regulation of vinculin. , 2006, Trends in cell biology.

[33]  A. Blanchard,et al.  Identification of the vinculin-binding site in the cytoskeletal protein alpha-actinin. , 1994, The Biochemical journal.

[34]  G. Torrie,et al.  Nonphysical sampling distributions in Monte Carlo free-energy estimation: Umbrella sampling , 1977 .

[35]  C. Turner,et al.  Focal adhesions: transmembrane junctions between the extracellular matrix and the cytoskeleton. , 1988, Annual review of cell biology.

[36]  M. Mofrad,et al.  Molecular mechanics of filamin's rod domain. , 2008, Biophysical journal.

[37]  S. Nosé.  A unified formulation of the constant temperature molecular dynamics methods , 1984 .

[38]  G. Bricogne,et al.  Vinculin activation by talin through helical bundle conversion , 2004, Nature.

[39]  D. Critchley,et al.  Analysis of the actin-binding domain of alpha-actinin by mutagenesis and demonstration that dystrophin contains a functionally homologous domain , 1992, The Journal of cell biology.

[40]  A. Blanchard,et al.  Identification of the vinculin-binding site in the cytoskeletal protein α-actinin , 1994 .

[41]  C. Otey,et al.  Dynamics of α‐actinin in focal adhesions and stress fibers visualized with α‐actinin‐green fluorescent protein , 2001 .

[42]  Berk Hess,et al.  LINCS: A linear constraint solver for molecular simulations , 1997, J. Comput. Chem..

[43]  Javad Golji,et al.  Molecular Mechanics of the α-Actinin Rod Domain: Bending, Torsional, and Extensional Behavior , 2009, PLoS Comput. Biol..

[44]  K. Taylor,et al.  A 3-D reconstruction of smooth muscle alpha-actinin by CryoEm reveals two different conformations at the actin-binding region. , 2004, Journal of molecular biology.

[45]  C. Otey,et al.  Dynamics of alpha-actinin in focal adhesions and stress fibers visualized with alpha-actinin-green fluorescent protein. , 2001, Cell motility and the cytoskeleton.

[46]  Clemens Vonrhein,et al.  Structural dynamics of alpha-actinin-vinculin interactions. , 2005, Molecular and cellular biology.

[47]  J. Wehland,et al.  Ligand recruitment by vinculin domains in transfected cells. , 1997, Journal of cell science.

[48]  D. Nietlispach,et al.  The vinculin binding sites of talin and alpha-actinin are sufficient to activate vinculin. , 2006, The Journal of biological chemistry.

[49]  Andrew E. Torda,et al.  The GROMOS biomolecular simulation program package , 1999 .

[50]  Deborah F. Kelly,et al.  Structure of the α-Actinin–Vinculin Head Domain Complex Determined by Cryo-electron Microscopy , 2006 .

[51]  J. Feramisco,et al.  Non-muscle alpha actinins are calcium-sensitive actin-binding proteins. , 1981, Nature.

[52]  Roger D. Kamm,et al.  Cellular mechanotransduction : diverse perspectives from molecules to tissues , 2009 .

[53]  K. Taylor,et al.  Novel structures for alpha-actinin:F-actin interactions and their implications for actin-membrane attachment and tension sensing in the cytoskeleton. , 2007, Journal of molecular biology.

[54]  S. Winder.  REVIEW: The membrane--cytoskeleton interface: the role of dystrophin and utrophin , 1997, Journal of Muscle Research & Cell Motility.