Distinct gain of function mechanism for the hot-spot mutant p53R175H

TP53 (p53) is the most commonly mutated gene in human cancers, and p53 missense mutations are present in more than 40% of all human tumors. Most p53 mutations are located within the DNA binding domain, including hotspot mutations R175H, R248W, and R273H. To elucidate the precise mechanism by which p53 missense mutants execute their gain-of-functions (GOFs) in vivo, we used a proteomic screen to identify any protein that recognizes the p53 DNA-binding domain (DBD) in a manner dependent on its mutation status. To do so, we first purified the potential binding proteins associated with the p53 DBD through multi-step affinity chromatography from a SFB-p53 H1299 stable cell line. The affinity-purified SFB-p53 interacting proteins were detected by liquid chromatography mass spectrometry/mass spectrometry (LC–MS/MS) and revealed a few cellular proteins that have been reported to interact with the DNA binding domain of p53, such as TP53BP1, USP28, and Sirt1. Interestingly, we also identified many new interacting proteins from the same complex.