p53 forms redox-dependent protein-protein interactions through cysteine 277

Reversible cysteine oxidation plays an essential role in redox signaling by reversibly altering protein structure and function. Cysteine oxidation may lead to intra- and intermolecular disulfide formation, and the latter can drastically stabilize protein-protein interactions in a more oxidizing milieu. The activity of the tumor suppressor p53 is regulated at multiple layers, including various post-translational modification (PTM) and protein-protein interactions. In the past decades, p53 has been shown to be a redox sensitive protein, and undergoes reversible cysteine oxidation both in vitro and in vivo. It is not clear however, whether p53 also forms intermolecular disulfides with interacting proteins and whether these redox-dependent interactions contribute to the regulation of p53. In the present study, by combining (co-)immunoprecipitation, quantitative Mass spectrometry and Western blot we found that p53 forms disulfide-dependent interactions with several proteins under oxidizing conditions. p53-Cys277 is required for most of the disulfide-dependent interactions, including those with 14-3-3 and 53BP1. Taken together, our findings uncovered a new form of p53 cysteine oxidation, which strengthened the biochemical features of p53 as a redox sensitive protein.