Characterization of 14-3-3-zeta Interactions with integrin tailsBonet, R., Vakonakis, I., Campbell, I.D.
(2013) J Mol Biol 425: 3060-3072
- PubMed: 23763993
- DOI: https://doi.org/10.1016/j.jmb.2013.05.024
- Primary Citation of Related Structures:
- PubMed Abstract:
Integrins are a family of heterodimeric (α+β) adhesion receptors that play key roles in many cellular processes. Integrins are unusual in that their functions can be modulated from both outside and inside the cell. Inside-out signaling is mediated by binding adaptor proteins to the flexible cytoplasmic tails of the α- and β-integrin subunits. Talin is one well-known intracellular activator, but various other adaptors bind to integrin tails, including 14-3-3-ζ, a member of the 14-3-3 family of dimeric proteins that have a preference for binding phosphorylated sequence motifs. Phosphorylation of a threonine in the β2 integrin tail has been shown to modulate β2/14-3-3-ζ interactions, and recently, the α4 integrin tail was reported to bind to 14-3-3-ζ and associate with paxillin in a ternary complex that is regulated by serine phosphorylation. Here, we use a range of biophysical techniques to characterize interactions between 14-3-3-ζ and the cytoplasmic tails of α4, β1, β2 and β3 integrins. The X-ray structure of the 14-3-3-ζ/α4 complex indicates a canonical binding mode for the α4 phospho-peptide, but unexpected features are also observed: residues outside the consensus 14-3-3-ζ binding motif are shown to be essential for an efficient interaction; in contrast, a short β2 phospho-peptide is sufficient for high-affinity binding to 14-3-3-ζ. In addition, we report novel 14-3-3-ζ/integrin tail interactions that are independent of phosphorylation. Of the integrin tails studied, the strongest interaction with 14-3-3-ζ is observed for the β1A variant. In summary, new insights about 14-3-3-ζ/integrin tail interactions that have implications for the role of these molecular associations in cells are described.
Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom. firstname.lastname@example.org