Structural basis for vinculin activation at sites of cell adhesion

Abstract

Vinculin is a highly conserved intracellular protein with a crucial role in the maintenance and regulation of cell adhesion and migration. In the cytosol, vinculin adopts a default autoinhibited conformation. On recruitment to cell-cell and cell-matrix adherens-type junctions, vinculin becomes activated and mediates various protein-protein interactions that regulate the links between F-actin and the cadherin and integrin families of cell-adhesion molecules. Here we describe the crystal structure of the full-length vinculin molecule (1,066 amino acids), which shows a five-domain autoinhibited conformation in which the carboxy-terminal tail domain is held pincer-like by the vinculin head, and ligand binding is regulated both sterically and allosterically. We show that conformational changes in the head, tail and proline-rich domains are linked structurally and thermodynamically, and propose a combinatorial pathway to activation that ensures that vinculin is activated only at sites of cell adhesion when two or more of its binding partners are brought into apposition.

Vinculin Phosphorylation at Tyr1065 Regulates Vinculin Conformation and Tension Development in Airway Smooth Muscle Tissues

“…Although talin binding by itself has been proposed to be sufficient to cause vinculin activation (29,30), most biochemical and structural analyses are consistent with the view that the activation of vinculin requires the simultaneous interaction of vinculin with at least two of its binding partners, actin and talin, which may promote the open conformation of vinculin by generating internal molecular stretching forces (25,28,31,32). The interaction of vinculin with acidic phospholipids and ␣-actinin may also contribute to the conversion of vinculin to an open conformation (33)(34)(35).…”

“…The vinculin molecule consists of a globular head domain with four helical bundle domains connected by a flexible linker to a short tail domain consisting of an additional helical bundle (25,26). The conformational state of the vinculin molecule can be reversibly regulated between an activated "open" state and an inactive "autoinhibited" state (14,15,18,19,25,27).…”

“…The conformational state of the vinculin molecule can be reversibly regulated between an activated "open" state and an inactive "autoinhibited" state (14,15,18,19,25,27). In the open state, binding sites for talin and ␣-actinin on the head domain of vinculin and binding sites for F-actin on the tail domain are exposed, enabling vinculin to form connections between the actin cytoskeleton and integrin adhesion complexes (14,19,26,28).…”

“…In the open state, binding sites for talin and ␣-actinin on the head domain of vinculin and binding sites for F-actin on the tail domain are exposed, enabling vinculin to form connections between the actin cytoskeleton and integrin adhesion complexes (14,19,26,28). In its closed conformation, a high affinity intramolecular interaction between the head and tail domains of the vinculin molecule obstructs the binding sites on vinculin for talin and ␣-actinin on the head domain and prevents actin binding to the tail domain (14,19,25,27).…”

Renal cell carcinoma with novel VCL–ALK fusion: new representative of ALK-associated tumor spectrum

“…The structure of the protein is well studied; VCL has a head domain (residues 1-835) and a tail domain (residues 896-1066) that are connected by a flexible hinge region. 38 VCL functions as an adhesion protein that couples extracellular matrix through integrins to the acto-myosin cytoskeleton. VCL binds talin at the head and actin at the tail; binding to talin opens hydrogen bonds, thereby allowing homodimerization of VCL molecules in their active conformational forms.…”