The p53 protein is a critical tumor suppressor that is mutated in over half of all human cancers. It plays essential roles in maintaining genomic integrity by modulating the cellular response to various types of genotoxic stress. Associating with over 270 proteins to date, one of the mechanisms pivotal to p53’s multifaceted activities is protein-protein interactions. As to how most of these molecules bind to and affect p53 function remains unclear. Here we present a combined structural and biophysical approach to study three p53-interacting partners: BRCA1, IFI16 and p53 affinity reagent in an attempt to elucidate the basis of how these proteins recognize, bind to and alter p53’s biochemical functions. We have biophysically characterized the central region of BRCA1 and examined how it acts as a disordered scaffold to mediate association with p53 and other proteins. Having a putative role as a tumor suppressor, we have determined the crystal structures of the HIN-A and HIN-B domains of IFI16 and find that they interact with the C-terminus and DNA-binding core domain of p53, respectively, and enhance the DNA binding and transactivation activities of p53. Most cancer hot spot mutations of p53 are localized in the core domain and are thermally destabilized. Attaining molecules that stabilize the p53 fold has therefore been regarded as an attractive approach for cancer therapy. Lastly, using a phage-displayed library, evidence is presented to demonstrate a proof-of-principle for generating synthetic affinity reagents to potentially restore the function of tumor-derived p53 core domain mutants.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/31836 |
| Date | 10 January 2012 |
| Creators | Liao, Jack Chun-Chieh |
| Contributors | Arrowsmith, Cheryl |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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