The electrostatic surface of MDM2 modulates the specificity of its interaction with phosphorylated and unphosphorylated p53 peptides

Abstract

Lane (2008) The electrostatic surface of MDM2 modulates the specificity of its interaction with phosphorylated and unphosphorylated p53 peptides, Cell Cycle, 7:5, 608-610, DOI: 10.4161/cc.7.5.5488To link to this article: https://doi.org/10.4161/cc.7.5.5488 Florescence anisotropy measurements using FAM-labelled p53 peptides showed that the binding of the peptides to MDM2 was dependant upon the phosphorylation of p53 at Thr18 and that this binding was modulated by the electrostatic properties of MDM2. In agreement with computational predictions, the binding to phosphorylated p53 peptide, in comparison to the unphosphorylated p53 peptide, was enhanced upon mutation of 3 key residues on the MDM2 surface.

The Tumor Suppressor p53: From Structures to Drug Discovery

“…Phosphorylation of Thr18 significantly reduces the affinity of TAD for MDM2 because of electrostatic repulsion between the phosphate group and a negatively charged patch on the MDM2 surface (Sakaguchi et al 2000;Schon et al 2002;Brown et al 2008). In contrast, phosphorylation at Thr18 and other sites within TAD can significantly enhance the affinity of TAD for p300 and its various subdomains (Ferreon et al 2009;Jenkins et al 2009;Lee et al 2009;Teufel et al 2009).…”

A spatiotemporal characterization of the effect of p53 phosphorylation on its interaction with MDM2

“…The suggestion that phosphorylation of these sites destabilizes p53-MDM2 interaction is supported by alanine mutagenesis experiments 23 and computer simulations. 18,24,39,40 The physical rationale for the destabilization of binding is usually ascribed to thermodynamic effects 18 however, kinetic effects have not been studied in either experimental or simulation studies. In this study, we turn our attention to at least one model that describes the kinetic aspects: the structure and dynamics of the p53-MDM2 'encounter complex' before and after p53 phosphorylation.…”

“…23 Computational models, partly validated by experiments, suggested that the effect of phosphorylation was attributed to enhancing elecrostatic repulsion in the region where Thr18 docks by placing the negatively charged phosphorylated Thr18 near anionic regions of the MDM2 surface. 18,24 Phosphorylation of Ser20, however, was found to be sufficient to disrupt the p53-MDM2 interaction.…”

“…higher dissociation constant; K d ) toward both wild-type p53 and pThr18 p53 peptides relative to wild-type MDM2: p53 system. 24 In order to validate our approach and to rationalize these observations, we computed the residence Figure 6. The experimental dissociation constants 24 ; K d (top panel) and the computed off-rate constants ; k off (bottom panel) for MDM2:p53, MDM2:p53(pThr18), 3 m-MDM2:p53 and 3 m-MDM2:p53 (pThr18) interactions.…”

“…24 In order to validate our approach and to rationalize these observations, we computed the residence Figure 6. The experimental dissociation constants 24 ; K d (top panel) and the computed off-rate constants ; k off (bottom panel) for MDM2:p53, MDM2:p53(pThr18), 3 m-MDM2:p53 and 3 m-MDM2:p53 (pThr18) interactions. k off »1/t; where t is the residence time of the dominant basin in each system.…”