4WRQ

Crystal Structure of 14-3-3 zeta with Chibby peptide

Summary for 4WRQ

• Entry DOI: 10.2210/pdb4wrq/pdb
• Descriptor: 14-3-3 protein zeta/delta, Chibby (3 entities in total)
• Functional Keywords: wnt signalling, hub, phosphorylation, signaling protein
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 4
• Total formula weight: 59852.84

Authors

Killoran, R.C.,Shilton, B.H.,Choy, W.Y. (deposition date: 2014-10-24, release date: 2015-05-06, Last modification date: 2024-10-30)

Primary citation

Killoran, R.C.,Fan, J.,Yang, D.,Shilton, B.H.,Choy, W.Y.
Structural Analysis of the 14-3-3 zeta /Chibby Interaction Involved in Wnt/ beta-Catenin Signaling.
Plos One, 10:e0123934-e0123934, 2015

PubMed Abstract: The partially disordered Chibby (Cby) is a conserved nuclear protein that antagonizes the Wnt/β-catenin signaling pathway. By competing with the Tcf/Lef family proteins for binding to β-catenin, Cby abrogates the β-catenin-mediated transcription of Wnt signaling genes. Additionally, upon phosphorylation on S20 by the kinase Akt, Cby forms a complex with 14-3-3 to facilitate the nuclear export of β-catenin, which represents another crucial mechanism for the regulation of Wnt signaling. To obtain a mechanistic understanding of the 14-3-3/Cby interaction, we have extensively characterized the complex using X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, and isothermal titration calorimetry (ITC). The crystal structure of the human 14-3-3ζ/Cby protein-peptide complex reveals a canonical binding mode; however the residue at the +2 position from the phosphorylated serine is shown to be uniquely oriented relative to other solved structures of 14-3-3 complexes. Our ITC results illustrate that although the phosphorylation of S20 is essential for Cby to recognize 14-3-3, residues flanking the phosphorylation site also contribute to the binding affinity. However, as is commonly observed in other 14-3-3/phosphopeptide crystal structures, residues of Cby flanking the 14-3-3 binding motif lack observable electron density. To obtain a more detailed binding interface, we have completed the backbone NMR resonance assignment of 14-3-3ζ. NMR titration experiments reveal that residues outside of the 14-3-3 conserved binding cleft, namely a flexible loop consisting of residues 203-210, are also involved in binding Cby. By using a combined X-ray and NMR approach, we have dissected the molecular basis of the 14-3-3/Cby interaction.

PubMed: 25909186
DOI: 10.1371/journal.pone.0123934

Experimental method

X-RAY DIFFRACTION (2.409 Å)