![]() The critical interacting residues (F19, W23 and L26) in the p53 wild-type peptide and conserved in the indicated stapled peptides are shaded. Sequence alignment of peptide ligands targeting the Mdm2 N-terminal domain. Whilst M62 also contributes to the binding of p53 peptide (residues 15 to 29 of p53, Figure 1), loss of this residue is mitigated by an extended network of Van der Waals contacts distributed along the Mdm2 binding cleft. In the case of the M62A mutation, substitution of the methionine removes a key packing interface required by Nutlin, significantly impairing binding. We have previously described the mutations M62A and Q24R in the N-terminal domain of Mdm2 that impart Nutlin-resistance by selectively reducing affinity for Nutlin but not p53. Binding is achieved by recapitulating interactions of three key p53 amino acid side chains (F19, W23, L26), with discrete pockets lining the hydrophobic cleft. ![]() ![]() It competes with p53 for binding to an extended hydrophobic cleft in the N-terminal domain of Mdm2. Nutlin-3a (hereafter termed Nutlin) is the proto-typical small molecule Mdm2 antagonist. Re-instatement of p53 effector functions has been demonstrated by inhibition of Mdm2 with both small molecule and peptide antagonists –. Mdm2 both inhibits the transactivation function of p53 and selectively ubiquitinates p53, targeting it for proteosomal degradation –. In malignancies with wild type p53 status, the activity of p53 is commonly attenuated through overexpression of Mdm2, a key negative regulator. Loss of p53 function, typically arising through point mutations is seen in 50% of all cancers. Triggered by stresses such as DNA damage and hypoxia, p53 elicits numerous cellular outcomes including cell cycle arrest and cell death. This does not alter the authors’ adherence to PLOS ONE Editorial policies and criteria.Ĭell fate is primarily governed by the p53 tumour suppressor. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Ĭompeting interests: Co-author Chandra Verma is a PLOS ONE Editorial Board member. All structure files are available from the PDB database (accession number 4UMN).įunding: This work was funded by the Agency for Science Technology and Research (A*STAR), Singapore. All relevant data are within the paper and its Supporting Information files. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.ĭata Availability: The authors confirm that all data underlying the findings are fully available without restriction. Received: Accepted: JPublished: August 12, 2014Ĭopyright: © 2014 Chee et al. Maki, Rush University Medical Center, United States of America (2014) Structure of a Stapled Peptide Antagonist Bound to Nutlin-Resistant Mdm2. The structure highlights the intrinsic plasticity present in both Mdm2 and the hydrocarbon staple moiety, and can be used to guide future iterations of both small molecules and stapled peptides for improved antagonists of Mdm2.Ĭitation: Chee SMQ, Wongsantichon J, Soo Tng Q, Robinson R, Joseph TL, Verma C, et al. Additionally, as seen in other stapled peptide structures, the hydrocarbon staple itself contributes to binding through favourable interactions with Mdm2. The stapled peptide relies on an extended network of interactions along the hydrophobic binding cleft of Mdm2 for high affinity binding. Here, we report the 2.00 Å crystal structure of a stapled peptide antagonist bound to Nutlin resistant Mdm2. A detailed understanding of how stapled peptides are recalcitrant to Mdm2 mutations conferring Nutlin-resistance will aid in the further development of potent Mdm2 antagonists. This Nutlin-resistant variant is not, however, refractory to binding and inhibition by stapled peptide antagonists targeting the same region of Mdm2. We have recently described a mutation in Mdm2 (M62A), which precludes binding of Nutlin, but not p53. Small molecules such as Nutlin have been developed to antagonise Mdm2, resulting in p53-dependent death of tumour cells. As key negative regulator of the p53 tumour suppressor, Mdm2 is an attractive therapeutic target.
0 Comments
Leave a Reply. |