Inhibition of the interaction between the p53
tumor suppressor and its negative regulator MDM2 is of great importance to
cancer therapy. The anti-apoptotic Bcl-2 family
proteins are also attractive anti-
cancer molecular targets, as they are key regulators of apoptotic cell death. Previously, we reported the interactions between the p53 transactivation domain (p53TAD) and diverse members of the anti-apoptotic Bcl-2 family
proteins. In this study, we investigated the binding of MDM2-inhibiting p53TAD
peptide analogues, p53-MDM2/MDMX inhibitor (PMI) and pDI, with anti-apoptotic Bcl-2 family
proteins, Bcl-XL and Bcl-2, by using NMR spectroscopy. The NMR chemical shift perturbation data demonstrated the direct binding of the p53
peptide analogues to Bcl-XL and Bcl-2 and showed that the PMI and pDI
peptides bind to a conserved hydrophobic groove of the anti-apoptotic Bcl-2 family
proteins. Furthermore, the structural model of the Bcl-XL/
PMI peptide complex showed that the binding mode of the
PMI peptide is highly similar to that of pro-apoptotic Bcl-2 homology 3 (BH3)
peptides. Finally, our structural comparison provided a molecular basis for how the same
PMI peptide can bind to two distinct anti-
cancer target
proteins Bcl-XL and MDM2, which may have potential applications for multi-targeting
cancer therapy.