Chee Sharon Min Qi, Wongsantichon Jantana, Soo Tng Quah, Robinson Robert, Joseph Thomas L, Verma Chandra, Lane David P, Brown Christopher J, Ghadessy Farid J
p53Lab, Agency for Science Technology and Research (A*STAR), Singapore, Singapore.
Institute of Molecular and Cellular Biology, A*STAR, Singapore, Singapore.
PLoS One. 2014 Aug 12;9(8):e104914. doi: 10.1371/journal.pone.0104914. eCollection 2014.
As key negative regulator of the p53 tumour suppressor, Mdm2 is an attractive therapeutic target. Small molecules such as Nutlin have been developed to antagonise Mdm2, resulting in p53-dependent death of tumour cells. We have recently described a mutation in Mdm2 (M62A), which precludes binding of Nutlin, but not p53. This Nutlin-resistant variant is not, however, refractory to binding and inhibition by stapled peptide antagonists targeting the same region of 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. Here, we report the 2.00 Å crystal structure of a stapled peptide antagonist bound to Nutlin resistant Mdm2. The stapled peptide relies on an extended network of interactions along the hydrophobic binding cleft of Mdm2 for high affinity binding. Additionally, as seen in other stapled peptide structures, the hydrocarbon staple itself contributes to binding through favourable interactions with 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.
作为p53肿瘤抑制因子的关键负调控因子，Mdm2是一个有吸引力的治疗靶点。已开发出如Nutlin等小分子来拮抗Mdm2，从而导致肿瘤细胞发生p53依赖性死亡。我们最近报道了Mdm2中的一个突变（M62A），该突变可阻止Nutlin的结合，但不影响p53的结合。然而，这种对Nutlin耐药的变体对靶向Mdm2同一区域的环肽拮抗剂的结合和抑制并不具有抗性。深入了解环肽如何对赋予Nutlin抗性的Mdm2突变具有抗性，将有助于进一步开发有效的Mdm2拮抗剂。在此，我们报道了一种与对Nutlin耐药的Mdm2结合的环肽拮抗剂的2.00 Å晶体结构。该环肽依赖于沿Mdm2疏水结合裂隙的广泛相互作用网络来实现高亲和力结合。此外，正如在其他环肽结构中所见，烃链本身通过与Mdm2的有利相互作用促进结合。该结构突出了Mdm2和烃链部分中存在的内在可塑性，可用于指导小分子和环肽的未来迭代，以改进Mdm2拮抗剂。
