Activation of a vinculin-binding site in the talin rod involves rearrangement of a five-helix bundle

• DOI: 10.1038/sj.emboj.7600285
• Publication Date: 2004-07-22T15:56:36Z
• Authors: Evangelos Papagri...; Alexandre R Gingras; Igor L Barsukov; Neil Bate; Ian J Fillingham; Bipin Patel; Ronald Frank; Wolfgang H Ziegler; Gordon CK Roberts; David R Critchley; Jonas Emsley
• Keywords: Models, Molecular; Talin; 0301 basic medicine; Protein Structure; Protein Folding; Nuclear Magnetic Resonance; Molecular Sequence Data; Protein Array Analysis; Ligands; 03 medical and health sciences; Models; Animals; Amino Acid Sequence; Nuclear Magnetic Resonance, Biomolecular; Binding Sites; Molecular; 500; Vinculin; Protein Structure, Tertiary; Mutation; Chickens; Hydrophobic and Hydrophilic Interactions; Sequence Alignment; Tertiary; Biomolecular; Protein Binding

The interaction between the cytoskeletal proteins talin and vinculin plays a key role in integrin-mediated cell adhesion and migration. We have determined the crystal structures of two domains from the talin rod spanning residues 482-789. Talin 482-655, which contains a vinculin-binding site (VBS), folds into a five-helix bundle whereas talin 656-789 is a four-helix bundle. We show that the VBS is composed of a hydrophobic surface spanning five turns of helix 4. All the key side chains from the VBS are buried and contribute to the hydrophobic core of the talin 482-655 fold. We demonstrate that the talin 482-655 five-helix bundle represents an inactive conformation, and mutations that disrupt the hydrophobic core or deletion of helix 5 are required to induce an active conformation in which the VBS is exposed. We also report the crystal structure of the N-terminal vinculin head domain in complex with an activated form of talin. Activation of the VBS in talin and the recruitment of vinculin may support the maturation of small integrin/talin complexes into more stable adhesions.