Biophysical Society Thematic Meeting - October 25-30, 2015

Polymers and Self Assembly: From Biology to Nanomaterials Poster Session II

25-POS Board 25 New Evidences to Support the Prion-like Behavior of Mutant p53 Adriani Lima , Jerson L. Silva, Guilherme A. De Oliveira. Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.

The human p53 is a nuclear phosphoprotein of 53 kDa activated in response of cellular stress. Upon activation it mediates specific responses, including cell-cycle arrest, apoptosis, and senescence. The majority of p53 mutations associated with cancer was screened in the DNA binding domain of the protein (DBD). The DBD is a domain of 25 kDa and mutations in this region favor non-native conformations, affecting their solubility and thermal stability. The changes in protein conformation can cause inactivation and formation of aggregated p53 . To verify the role of aggregation, and to expand the p53 aggregation hypothesis based on the prion like specific mutations were used to stabilize and destabilize p53. We evaluate whether wild type p53 (WT) and mutants; Y220C with a large loss of thermodynamic stability, double mutant (DM) (Y236F / T253I), and quadruple mutant (QM) (M133L / V203A / N239Y / N268D), which stabilizes p53 by 1.6 kcal / mol and 2, 65 kcal / mol, respectively could aggregate as amyloids under near physiological conditions. We also investigated if studied mutants are able to seed aggregation of the wild-type form p53. The aggregation kinetics of p53 was monitored by measuring the binding of the protein to Thioflavin T (ThT) and light scattering. Our results show that the cancer – related mutant Y220C has a faster aggregation kinetics when compared to the wild-type, DM and QM-p53C at 37 ° C. It was also observed that seeds of this mutants (Y220C) accelerate the aggregation of wild p53C compared to seeds obtained from the stabilized mutants. These data support the prion-like behavior of a cancer-related p53 mutants and open up new discussions for the coaggregation vs. prion-like mechanisms of p53 aggreagation in cancer.

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