A Vinculin Binding Domain from the Talin Rod Unfolds to Form a Complex with the Vinculin Head

• DOI: 10.1016/j.str.2004.11.006
• Publication Date: 2005-01-12T12:18:24Z
• Authors: Ian Fillingham; Alexandre R. Gingras; Evangelos Papagri...; Bipin Patel; Jonas Emsley; David R. Critchley; Gordon C.K. Roberts; Igor L. Barsukov
• Keywords: Electrophoresis; Models, Molecular; Talin; 0301 basic medicine; Protein Structure; Secondary; 572; Nuclear Magnetic Resonance; Molecular Sequence Data; Sequence Homology; Crystallography, X-Ray; Spectrum Analysis, Raman; Protein Structure, Secondary; 03 medical and health sciences; Models; Structural Biology; Amino Acid Sequence; Raman; Molecular Biology; Nuclear Magnetic Resonance, Biomolecular; Crystallography; Polyacrylamide Gel; Binding Sites; Sequence Homology, Amino Acid; Spectrum Analysis; Molecular; 500; Actins; Recombinant Proteins; Vinculin; Protein Structure, Tertiary; Solutions; Amino Acid; Cytoskeletal Proteins; X-Ray; Electrophoresis, Polyacrylamide Gel; Hydrophobic and Hydrophilic Interactions; Tertiary; Biomolecular; Protein Binding

The cytoskeletal protein talin plays a key role in activating integrins and in coupling them to the actin cytoskeleton. Its N-terminal globular head, which binds beta integrins, is linked to an extended rod having a C-terminal actin binding site and several vinculin binding sites (VBSs). The NMR structure of residues 755-889 of the rod (containing a VBS) is shown to be an amphipathic four-helix bundle with a left-handed topology. A talin peptide corresponding to the VBS binds the vinculin head; the X-ray crystallographic structure of this complex shows that the residues which interact with vinculin are buried in the hydrophobic core of the talin fragment. NMR shows that the interaction involves a major structural change in the talin fragment, including unfolding of one of its helices, making the VBS accessible to vinculin. Interestingly, the talin 755-889 fragment binds more than one vinculin head molecule, suggesting that the talin rod may contain additional as yet unrecognized VBSs.