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The domain structure of talin: residues 1815-1973 form a five-helix bundle containing a cryptic vinculin-binding site.

ABSTRACT: Talin is a large flexible rod-shaped protein that activates the integrin family of cell adhesion molecules and couples them to cytoskeletal actin. Its rod region consists of a series of helical bundles. Here we show that residues 1815-1973 form a 5-helix bundle, with a topology unique to talin which is optimally suited for formation of a long rod such as talin. This is much more stable than the 4-helix (1843-1973) domain described earlier and as a result its vinculin binding sequence is inaccessible to vinculin at room temperature, with implications for the overall mechanism of the talin-vinculin interaction.

SUBMITTER: Goult BT

PROVIDER: S-EPMC2887493 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature

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The domain structure of talin: residues 1815-1973 form a five-helix bundle containing a cryptic vinculin-binding site.

Goult Benjamin T BT Gingras Alexandre R AR Bate Neil N Barsukov Igor L IL Critchley David R DR Roberts Gordon C K GC

FEBS letters 20100420 11

Talin is a large flexible rod-shaped protein that activates the integrin family of cell adhesion molecules and couples them to cytoskeletal actin. Its rod region consists of a series of helical bundles. Here we show that residues 1815-1973 form a 5-helix bundle, with a topology unique to talin which is optimally suited for formation of a long rod such as talin. This is much more stable than the 4-helix (1843-1973) domain described earlier and as a result its vinculin binding sequence is inaccess ...[more]

PMID: 20399778

Similar Datasets

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

Project description: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.

| S-EPMC514914 | biostudies-literature

Talin contains three similar vinculin-binding sites predicted to form an amphipathic helix.

Project description:Using recombinant talin polypeptides and an SDS/PAGE-blot overlay assay, we have previously identified three regions of talin that are involved in binding to vinculin [Gilmore, Wood, Ohanian, Jackson, Patel, Rees, Hynes and Critchley (1993) J. Cell Biol. 122, 337-347]. We have confirmed these observations by using a yeast two-hybrid assay and shown that talin residues 498-656, 852-950 and 1929-2029 are each capable of binding to vinculin residues 1-258. We have further defined the three vinculin-binding sites in talin to residues 607-636, 852-876 and 1944-1969; alignment of these sequences shows 59% similarity, although there are only two identical residues. Predictions of secondary structure indicate that this vinculin-binding motif forms an amphipathic alpha-helix. The hydrophobic face of helix 607-636 contains three aligned leucines (residues 608, 615 and 622), which show conservative substitutions in the other two sites. To test the possibility that this might constitute a leucine zipper involved in vinculin binding, we mutated each leucine residue to an alanine. The results showed that this leucine repeat is not essential to the interaction between talin and vinculin. We also used the yeast two-hybrid system to define further the talin-binding site within vinculin residues 1-258. C-terminal deletions made in accordance with exon boundaries showed that vinculin residues 1-167 are capable of interacting with each of the three vinculin-binding sites in talin. However, all N-terminal deletions abolished binding. The results suggest that the talin-binding site in vinculin has a relatively complex fold, whereas the vinculin-binding motif in talin is contained within a short linear peptide sequence that is repeated three times in the talin rod domain.

| S-EPMC1220354 | biostudies-other

Monomeric and dimeric conformation of the vinculin tail five-helix bundle in solution studied by EPR spectroscopy.

Project description:The cytoskeletal adaptor protein vinculin plays an important role in the control of cell adhesion and migration, linking the actin cytoskeleton to adhesion receptor complexes in cell adhesion sites. The conformation of the vinculin tail dimer, which is crucial for protein function, was analyzed using site-directed spin labeling in electron paramagnetic resonance spectroscopy. Interspin distances for a set of six singly and four doubly spin-labeled mutants of the tail domain of vinculin were determined and used as constraints for modeling of the vinculin tail dimer. A comparison of the results obtained by molecular dynamic simulations and a rotamer library approach reveals that the crystal structure of the vinculin tail monomer is essentially preserved in aqueous solution. The orientation of monomers within the dimer observed previously by x-ray crystallography agrees with the solution electron paramagnetic resonance data. Furthermore, the distance between positions 1033 is shown to increase by >3 nm upon interaction of the vinculin tail domain with F-actin.

| S-EPMC3183806 | biostudies-literature

Direct observation of a coil-to-helix contraction triggered by vinculin binding to talin.

Project description:Vinculin binds unfolded talin domains in focal adhesions, which recruits actin filaments to reinforce the mechanical coupling of this organelle. However, it remains unknown how this interaction is regulated and its impact on the force transmission properties of this mechanotransduction pathway. Here, we use magnetic tweezers to measure the interaction between vinculin head and the talin R3 domain under physiological forces. For the first time, we resolve individual binding events as a short contraction of the unfolded talin polypeptide caused by the reformation of the vinculin-binding site helices, which dictates a biphasic mechanism that regulates this interaction. Force favors vinculin binding by unfolding talin and exposing the vinculin-binding sites; however, the coil-to-helix contraction introduces an energy penalty that increases with force, defining an optimal binding regime. This mechanism implies that the talin-vinculin-actin association could operate as a negative feedback mechanism to stabilize force on focal adhesions.

| S-EPMC7244311 | biostudies-literature

Molecular dynamics study of talin-vinculin binding.

Project description:Cells can sense mechanical force in regulating focal adhesion assembly. One vivid example is the force-induced recruitment of vinculin to reinforce initial contacts between a cell and the extracellular matrix. Crystal structures of the unbound proteins and bound complex between the vinculin head subdomain (Vh1) and the talin vinculin binding site 1 (VBS1) indicate that vinculin undergoes a conformational change upon binding to talin. However, the molecular basis for this event and the precise nature of the binding pathway remain elusive. In this article, molecular dynamics is used to investigate the binding mechanism of Vh1 and VBS1 under minimal constraints to facilitate binding. One simulation demonstrates binding of the two molecules in the complete absence of external force. VBS1 makes early hydrophobic contact with Vh1 by positioning the critical hydrophobic residues (L608, L615, and L622) in the groove formed by helices 1 and 2 of Vh1. The solvent-exposed hydrophobic residues (V619 and L623) then gradually penetrate the hydrophobic core of Vh1, thus further separating helix 1 from helix 2. These critical residues are highly conserved as large hydrophobic side groups in other vinculin binding sites; studies also have demonstrated that these residues are essential in Vh1-VBS1 binding. Similar binding mechanisms are also demonstrated in separate molecular dynamics simulations of Vh1 binding to other vinculin binding sites both in talin and alpha-actinin.

| S-EPMC2483755 | biostudies-literature

Chlamydial virulence factor TarP mimics talin to disrupt the talin-vinculin complex.

Project description:Vinculin is a central component of mechanosensitive adhesive complexes that form between cells and the extracellular matrix. A myriad of infectious agents mimic vinculin binding sites (VBS), enabling them to hijack the adhesion machinery and facilitate cellular entry. Here, we report the structural and biochemical characterisation of VBS from the chlamydial virulence factor TarP. Whilst the affinities of isolated VBS peptides from TarP and talin for vinculin are similar, their behaviour in larger fragments is markedly different. In talin, VBS are cryptic and require mechanical activation to bind vinculin, whereas the TarP VBS are located in disordered regions, and so are constitutively active. We demonstrate that the TarP VBS can uncouple talin:vinculin complexes, which may lead to adhesion destabilisation.

| S-EPMC6001692 | biostudies-literature

Atomistic folding simulations of the five-helix bundle protein ?(6?85).

Project description:Protein folding is a classic grand challenge that is relevant to numerous human diseases, such as protein misfolding diseases like Alzheimer’s disease. Solving the folding problem will ultimately require a combination of theory, simulation, and experiment, with theory and simulation providing an atomically detailed picture of both the thermodynamics and kinetics of folding and experimental tests grounding these models in reality. However, theory and simulation generally fall orders of magnitude short of biologically relevant time scales. Here we report significant progress toward closing this gap: an atomistic model of the folding of an 80-residue fragment of the ? repressor protein with explicit solvent that captures dynamics on a 10 milliseconds time scale. In addition, we provide a number of predictions that warrant further experimental investigation. For example, our model’s native state is a kinetic hub, and biexponential kinetics arises from the presence of many free-energy basins separated by barriers of different heights rather than a single low barrier along one reaction coordinate (the previously proposed incipient downhill folding scenario).

| S-EPMC3043158 | biostudies-literature

Mechanical activation of vinculin binding to talin locks talin in an unfolded conformation.

Project description:The force-dependent interaction between talin and vinculin plays a crucial role in the initiation and growth of focal adhesions. Here we use magnetic tweezers to characterise the mechano-sensitive compact N-terminal region of the talin rod, and show that the three helical bundles R1-R3 in this region unfold in three distinct steps consistent with the domains unfolding independently. Mechanical stretching of talin R1-R3 enhances its binding to vinculin and vinculin binding inhibits talin refolding after force is released. Mutations that stabilize R3 identify it as the initial mechano-sensing domain in talin, unfolding at ?5?pN, suggesting that 5?pN is the force threshold for vinculin binding and adhesion progression.

| S-EPMC3980218 | biostudies-literature

Vinculin activation is necessary for complete talin binding.

Project description:Focal adhesions are critical to a number of cellular processes that involve mechanotransduction and mechanical interaction with the cellular environment. The growth and strengthening of these focal adhesions is dependent on the interaction between talin and vinculin. This study investigates said interaction and how vinculin activation influences it. Using molecular dynamics, the interaction between talin's vinculin binding site (VBS) and vinculin's domain 1 (D1) is simulated both before and after vinculin activation. The simulations of VBS binding to vinculin before activation suggest the proximity of the vinculin tail to D1 prevents helical movement in D1 and thus prevents binding of VBS. In contrast, interaction of VBS with activated vinculin shows the possibility of complete VBS insertion into D1. In the simulations of both activated and autoinhibited vinculin where VBS fails to fully bind, VBS demonstrates significant hydrophobic interaction with surface residues in D1. These interactions link VBS to D1 even without its proper insertion into the hydrophobic core. Together these simulations suggest VBS binds to vinculin with the following mechanism: 1), VBS links to D1 via surface hydrophobic interactions; 2), vinculin undergoes activation and D1 is moved away from the vinculin tail; 3), helices in D1 undergo conformational change to allow VBS binding; and 4), VBS inserts itself into the hydrophobic core of D1.

| S-EPMC3021670 | biostudies-literature

Vinculin controls talin engagement with the actomyosin machinery.

Project description:The link between extracellular-matrix-bound integrins and intracellular F-actin is essential for cell spreading and migration. Here, we demonstrate how the actin-binding proteins talin and vinculin cooperate to provide this link. By expressing structure-based talin mutants in talin null cells, we show that while the C-terminal actin-binding site (ABS3) in talin is required for adhesion complex assembly, the central ABS2 is essential for focal adhesion (FA) maturation. Thus, although ABS2 mutants support cell spreading, the cells lack FAs, fail to polarize and exert reduced force on the surrounding matrix. ABS2 is inhibited by the preceding mechanosensitive vinculin-binding R3 domain, and deletion of R2R3 or expression of constitutively active vinculin generates stable force-independent FAs, although cell polarity is compromised. Our data suggest a model whereby force acting on integrin-talin complexes via ABS3 promotes R3 unfolding and vinculin binding, activating ABS2 and locking talin into an actin-binding configuration that stabilizes FAs.

| S-EPMC4686655 | biostudies-literature

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