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Structure of HIV-1 Capsid Assemblies by Cryo-electron Microscopy and Iterative Helical Real-space Reconstruction
Published on: August 9, 2011
Structure of the alpha-actinin-vinculin head domain complex determined by cryo-electron microscopy
Deborah F Kelly1, Dianne W Taylor, Constantina Bakolitsa
1Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4380, USA.
Abstract:
The vinculin binding site on alpha-actinin was determined by cryo-electron microscopy of 2D arrays formed on phospholipid monolayers doped with a nickel chelating lipid. Chicken smooth muscle alpha-actinin was cocrystallized with the beta1-integrin cytoplasmic domain and a vinculin fragment containing residues 1-258 (vinculin(D1)). Vinculin(D1) was located at a single site on alpha-actinin with 60-70% occupancy. In these arrays, alpha-actinin lacks molecular 2-fold symmetry and the two ends of the molecule, which contain the calmodulin-like and actin binding domains, are held in distinctly different environments. The vinculin(D1) difference density has a shape very suggestive of the atomic structure. The atomic model of the complex juxtaposes the alpha-actinin binding site on vinculin(D1) with the N-terminal lobe of the calmodulin-like domain on alpha-actinin. The results show that the interaction between two species with weak affinity can be visualized in a membrane-like environment.
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