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Structural diversity in integrin/talin interactions.

ABSTRACT: The adhesion of integrins to the extracellular matrix is regulated by binding of the cytoskeletal protein talin to the cytoplasmic tail of the ?-integrin subunit. Structural studies of this interaction have hitherto largely focused on the ?3-integrin, one member of the large and diverse integrin family. Here, we employ NMR to probe interactions and dynamics, revealing marked structural diversity in the contacts between ?1A, ?1D, and ?3 tails and the Talin1 and Talin2 isoforms. Coupled with analysis of recent structures of talin/? tail complexes, these studies elucidate the thermodynamic determinants of this heterogeneity and explain why the Talin2/?1D isoforms, which are co-localized in striated muscle, form an unusually tight interaction. We also show that talin/integrin affinity can be enhanced 1000-fold by deleting two residues in the ? tail. Together, these studies illustrate how the integrin/talin interaction has been fine-tuned to meet varying biological requirements.

SUBMITTER: Anthis NJ

PROVIDER: S-EPMC3157975 | biostudies-literature | 2010 Dec

REPOSITORIES: biostudies-literature

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Structural diversity in integrin/talin interactions.

Anthis Nicholas J NJ Wegener Kate L KL Critchley David R DR Campbell Iain D ID

Structure (London, England : 1993) 20101201 12

The adhesion of integrins to the extracellular matrix is regulated by binding of the cytoskeletal protein talin to the cytoplasmic tail of the β-integrin subunit. Structural studies of this interaction have hitherto largely focused on the β3-integrin, one member of the large and diverse integrin family. Here, we employ NMR to probe interactions and dynamics, revealing marked structural diversity in the contacts between β1A, β1D, and β3 tails and the Talin1 and Talin2 isoforms. Coupled with analy ...[more]

PMID: 21134644

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Beta integrin tyrosine phosphorylation is a conserved mechanism for regulating talin-induced integrin activation.

Project description:Integrins are large membrane-spanning receptors fundamental to cell adhesion and migration. Integrin adhesiveness for the extracellular matrix is activated by the cytoskeletal protein talin via direct binding of its phosphotyrosine-binding-like F3 domain to the cytoplasmic tail of the beta integrin subunit. The phosphotyrosine-binding domain of the signaling protein Dok1, on the other hand, has an inactivating effect on integrins, a phenomenon that is modulated by integrin tyrosine phosphorylation. Using full-length tyrosine-phosphorylated (15)N-labeled beta3, beta1A, and beta7 integrin tails and an NMR-based protein-protein interaction assay, we show that talin1 binds to the NPXY motif and the membrane-proximal portion of beta3, beta1A, and beta7 tails, and that the affinity of this interaction is decreased by integrin tyrosine phosphorylation. Dok1 only interacts weakly with unphosphorylated tails, but its affinity is greatly increased by integrin tyrosine phosphorylation. The Dok1 interaction remains restricted to the integrin NPXY region, thus phosphorylation inhibits integrin activation by increasing the affinity of beta integrin tails for a talin competitor that does not form activating membrane-proximal interactions with the integrin. Key residues governing these specificities were identified by detailed structural analysis, and talin1 was engineered to bind preferentially to phosphorylated integrins by introducing the mutation D372R. As predicted, this mutation affects talin1 localization in live cells in an integrin phosphorylation-specific manner. Together, these results indicate that tyrosine phosphorylation is a common mechanism for regulating integrin activation, despite subtle differences in how these integrins interact with their binding proteins.

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