UC San Diego

Tumor suppressor protein p53 plays a pivotal role in responding to the presence of cellular stress, where activation of p53 leads to induction of cell cycle arrest, DNA repair, and apoptosis. Mutations in p53 were present in 50% of cancer cases, where 95% of malignant tumors were caused by missense mutations in the DNA binding domain, emphasizing its importance in cancer research. Recent studies have demonstrated the aggregations of p53 have the propensity of transforming into amyloid oligomers and fibrils, which were present in cancer cells. The goal of this thesis is to examine the diversity of mutant p53 DBD behaviors, specifically the recently observed amyloid fibril formation of p53 DBD, highlighting a new gain of function characteristic. To further assess the prion-like behavior of the amyloid fibrils, a seeding assay was conducted, which showed a gain of function, dominant negative effect of mutant p53DBD R248Q. The wild-type p53DBD and its mutant forms displayed the propensity to form amyloid fibrils with differing rates amongst each other. To supplement our understanding of the molecular basis of filament packing, structural studies of mutant p53DBD were conducted in order to examine the crystal packing, which showed evident differences in alignment and contacts within their unit cell. Examination of wild-type p73DBD capabilities to rescue mutant p53DBD proved to be inconclusive in a heterogeneous Thioflavin T fluorescence assay