PMID: 26888287 , Related PDB ids: 5D2D, 5D3E, 5D3F

Authors:

Stevers LM, Lam CV, Leysen SF, Meijer FA, van Scheppingen DS, de Vries RM, Carlile GW, Milroy LG, Thomas DY, Brunsveld L, Ottmann C

Title:

Characterization and small-molecule stabilization of the multisite tandem binding between 14-3-3 and the R domain of CFTR.

Journal:

Proc Natl Acad Sci U S A. 2016 Mar 1;113(9):E1152-61. doi:, 10.1073/pnas.1516631113. Epub 2016 Feb 17.

Abstract:

Cystic fibrosis is a fatal genetic disease, most frequently caused by the retention of the CFTR (cystic fibrosis transmembrane conductance regulator) mutant protein in the endoplasmic reticulum (ER). The binding of the 14-3-3 protein to the CFTR regulatory (R) domain has been found to enhance CFTR trafficking to the plasma membrane. To define the mechanism of action of this protein-protein interaction, we have examined the interaction in vitro. The disordered multiphosphorylated R domain contains nine different 14-3-3 binding motifs. Furthermore, the 14-3-3 protein forms a dimer containing two amphipathic grooves that can potentially bind these phosphorylated motifs. This results in a number of possible binding mechanisms between these two proteins. Using multiple biochemical assays and crystal structures, we show that the interaction between them is governed by two binding sites: The key binding site of CFTR (pS768) occupies one groove of the 14-3-3 dimer, and a weaker, secondary binding site occupies the other binding groove. We show that fusicoccin-A, a natural-product tool compound used in studies of 14-3-3 biology, can stabilize the interaction between 14-3-3 and CFTR by selectively interacting with a secondary binding motif of CFTR (pS753). The stabilization of this interaction stimulates the trafficking of mutant CFTR to the plasma membrane. This definition of the druggability of the 14-3-3-CFTR interface might offer an approach for cystic fibrosis therapeutics.