The p53 DNA-Binding (Core) Domain can form a prion that seeds prion formation in full-length p53.

The p53 tumor suppressor is frequently inactivated in human cancers, often through mutations in its core-domain. Here, we developed a yeast reporter system in S. cerevisiae to investigate whether the p53 core-domain can function as a prion-forming domain. By using a chimeric protein (CD-FDp) combining the p53 Core Domain and the Functional Domain of the yeast prion protein Ure2p, we demonstrate that inactive CD-FDp forms heritable, self-propagating aggregates. These aggregates exhibit canonical prion properties, including dominance, non-Mendelian segregation, and cytoduction-mediated transmission. CD-FDp prionization is independent of canonical chaperones (Hsp104, Hsp70, Hsp90), distinguishing it from classical yeast prions. Prionized CD-FDp enhances the formation of amyloid-like foci in full-length p53-EYFP, as evidenced by Thioflavin T staining, and can transmit its prion state to full-length p53 via cytoplasmic transfer. This indicates that CD-FDp propagons can induce structural conversion of p53, supporting an autocatalytic aggregation model. Using a Luria-Delbrück fluctuation assay, we quantified the prionization propensity of wild-type and cancer-associated p53 core-domain mutants. While most mutants (e.g., R273H, R282W) showed inactivation frequencies similar to wild-type, the R175H mutant exhibited an ∼ 18-fold increase in prionization frequency, which correlates with its known aggregation propensity in human cancers. This yeast system thus provides a quantitative platform to assess the prion-like behavior of p53 mutants and screen for inhibitors of p53 inactivation. Our findings establish p53 core-domain as a novel, structurally distinct prion-forming domain and offer a powerful experimental framework for studying p53 inactivation mechanisms, with potential implications for cancer therapeutics.