Subcellular Localization of Talin Is Regulated by Inter-domain Interactions
ABSTRACT Talin, which is composed of head (THD) and rod domains, plays an important role in cell adhesion events in diverse species including most metazoans and Dictyostelium discoideum. Talin is abundant in the cytosol; however, it mediates adhesion by associating with integrins in the plasma membrane where it forms a primary link between integrins and the actin cytoskeleton. Cells modulate the partitioning of talin between the plasma membrane and the cytosol to control cell adhesion. Here, we combine nuclear magnetic resonance spectroscopy (NMR) with subcellular fractionation to characterize two distinct THD-rod domain interactions that control the interaction of talin with the actin cytoskeleton or its localization to the plasma membrane. An interaction between a discrete vinculin-binding region of the rod (VBS1/2a; Tln1(482-787)), and the THD restrains talin from interacting with the plasma membrane. Furthermore, we show that vinculin binding to VBS1/2a results in talin recruitment to the plasma membrane. Thus, we have structurally defined specific inter-domain interactions between THD and the talin rod domain that regulate the subcellular localization of talin.
- SourceAvailable from: Ammad Aslam Khan
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- "Among other highly ranked traces, K295 is involved in Talin–Actin binding, K364 in inter-domain interactions (Banno et al., 2012), F370 in Integrin activation (de Pereda et al., 2005), D372 in Talin localization in cells (Anthis et al., 2009), I356 in Integrin activation (Barsukov et al., 2003) and G394 in auto-inhibition of Talin Goksoy et al., 2008 (Fig. 7). Merlin (Neurofibromatosis-2) was second protein considered for ETA with Kindlins and Homo sapiens Merlin structure (PDB ID 3U8Z) (Yogesha et al., 2011) was used for structural mapping. "
ABSTRACT: Kindlin proteins represent a novel family of evolutionarily conserved FERM domain containing proteins (FDCPs) and are members of B4.1 superfamily. Kindlins consist of three conserved protein homologs in vertebrates: Kindlin-1, Kindlin-2 and Kindlin-3. All three homologs are associated with focal adhesions and are involved in integrin activation. FERM domain of each Kindlin is bipartite and plays a key role in integrin activation. A single ancestral Kindlin protein can be traced back to earliest metazoans, e.g., to Parazoa. This protein underwent multiple rounds of duplication in vertebrates, leading to the present Kindlin family. In this study, we trace phylogenetic and evolutionary history of Kindlin FERM domain with respect to FERM domain of other FDCPs. We show that FERM domain in Kindlin homologs is conserved among Kindlins but amount of conservation is less in comparison with FERM domain of other members in B4.1 superfamily. Furthermore, insertion of Pleckstrin Homology like domain in Kindlin FERM domain has important evolutionary and functional consequences. Important residues in Kindlins are traced and ranked according to their evolutionary significance. The structural and functional significance of high ranked residues is highlighted and validated by their known involvement in Kindlin associated diseases. In light of these findings, we hypothesize that FERM domain originated from a proto-Talin protein in unicellular or proto-multicellular organism and advent of multi-cellularity was accompanied by burst of FDCPs, which supported multi-cellularity functions required for complex organisms. This study helps in developing a better understanding of evolutionary history of FERM domain of FDCPs and the role of FERM domain in metazoan evolution.Molecular Phylogenetics and Evolution 08/2014; 80. DOI:10.1016/j.ympev.2014.08.008 · 4.02 Impact Factor
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- "A structural model of fulllength talin, derived from the combination of crystallographic data and electron microscopy reconstruction, suggests that both the head and the C-terminal ABD are masked in the dimeric inactive talin (Goult et al., 2013a). In the inactive state, F2 and F3 must be released from autoinhibitory contacts with the R1-R2 and R9 domains of the rod respectively (Banno et al., 2012; Goult et al., 2009) (Fig. 3A). The mechanism by which talin is initially activated is still unclear. "
ABSTRACT: Focal adhesions are clusters of integrin transmembrane receptors that mechanically couple the extracellular matrix to the actin cytoskeleton during cell migration. Focal adhesions sense and respond to variations in force transmission along a chain of protein-protein interactions linking successively actin filaments, actin binding proteins, integrins and the extracellular matrix to adapt cell-matrix adhesion to the composition and mechanical properties of the extracellular matrix. This review focuses on the molecular mechanisms by which actin binding proteins integrate actin dynamics, mechanotransduction and integrin activation to control force transmission in focal adhesions.European journal of cell biology 11/2013; DOI:10.1016/j.ejcb.2013.10.009 · 3.70 Impact Factor
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ABSTRACT: The activation of heterodimeric (α/β) integrin transmembrane receptors by cytosolic protein talin is crucial for regulating diverse cell-adhesion-dependent processes, including blood coagulation, tissue remodeling, and cancer metastasis. This process is triggered by the coincident binding of N-terminal FERM (four-point-one-protein/ezrin/radixin/moesin) domain of talin (talin-FERM) to the inner membrane surface and integrin β cytoplasmic tail, but how these binding events are spatiotemporally regulated remains obscure. Here we report the crystal structure of a dormant talin, revealing how a C-terminal talin rod segment (talin-RS) self-masks a key integrin-binding site on talin-FERM via a large interface. Unexpectedly, the structure also reveals a distinct negatively charged surface on talin-RS that electrostatically hinders the talin-FERM binding to the membrane. Such a dual inhibitory topology for talin is consistent with the biochemical and functional data, but differs significantly from a previous model. We show that upon enrichment with phosphotidylinositol-4,5-bisphosphate (PIP2) - a known talin activator, membrane strongly attracts a positively charged surface on talin-FERM and simultaneously repels the negatively charged surface on talin-RS. Such an electrostatic "pull-push" process promotes the relief of the dual inhibition of talin-FERM, which differs from the classic "steric clash" model for conventional PIP2-induced FERM domain activation. These data therefore unravel a new type of membrane-dependent FERM domain regulation and illustrate how it mediates the talin on/off switches to regulate integrin transmembrane signaling and cell adhesion.Cell Research advance online publication 19 June 2012; doi:10.1038/cr.2012.97.Cell Research 06/2012; 22(11). DOI:10.1038/cr.2012.97 · 11.98 Impact Factor