Structure of the complex between phosphorylated substrates and the SCF β-TrCP ubiquitin ligase receptor: a combined NMR, molecular modeling, and docking approach

The binding of phosphorylated peptides to the receptor plays a major role in many basic cellular processes in a variety of pathological states. Human β-TrCP is a key component of a recently characterized E3 ubiquitin ligase complex that regulates protein degradation through the ubiquitin-dependent proteasome pathway. Docking studies were carried out to explore the structural requirements for the β-TrCP substrates. Docking studies were performed on the bound conformation of the phosphorylated peptides determined by NMR, whereas the β-TrCP structure was derived by X-ray from Protein Data Bank. After the docking calculation, during which the peptides were conformationally restrained, the complex presented herein was analyzed in terms of ligand-protein interactions and properties of contacting surfaces. The structural requirements for phosphorylated substrates in interaction with β-TrCP were explored and compared with experimental data from TRNOESY and STD NMR results. The analysis revealed that the bend of the peptide structures, which is indispensable for β-TrCP recognition, aligns two charged phosphate groups and a central hydrophobic group in a favorable arrangement that leads to the burial of the peptide surface in the binding cleft upon complexation. Through docking simulations, we have identified different specific binding pockets of β-TrCP according to the ligand in interaction. These data should be valuable in the rational design of a ligand to be used in therapeutic approaches.


Nathalie Evrard-Todeschi, Julien Pons, Josyane Gharbi-Benarous, Gildas Bertho, Richard Benarous, Jean-Pierre Girault
December 1, 2008
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