Probing Life and Death Decisions with semisynthetic ‘designer’ p53
The tumour suppressor protein p53 orchestrates the response to cell damage and – if necessary – induces controlled cell death. It thus plays a central role in preventing cancer and is the most frequently mutated protein in cancer. p53 is tightly regulated by post-translational modifications (PTMs), many of which occur on the intrinsically disordered N- and C-terminal tails. The precise mechanisms through which p53 PTMs operate are difficult to elucidate due to the complexity of p53 signalling and challenges associated with preparing site-specifically modified p53 for in vitro studies. To address these issues, we have developed a protein semi-synthesis strategy to access p53 in defined PTM states.1 Using such ‘designer’ phospho-p53 variants we have probed the mechanism of p53 activation through phosphorylation in vitro. Moreover, we found that the spontaneous rearrangement of an asparagine to an isoaspartate residue in p53 reconfigures binding partner specificity, which suggests that p53 can act as a molecular time bomb. Given the importance of PTMs in p53 signalling, we believe that our chemistry-driven approach will contribute greatly to a mechanistic understanding of how this protein makes cellular life and death decisions.
The tumour suppressor protein p53 orchestrates the response to cell damage and – if necessary – induces controlled cell death. It thus plays a central role in preventing cancer and is the most frequently mutated protein in cancer. p53 is tightly regulated by post-translational modifications (PTMs), many of which occur on the intrinsically disordered N- and C-terminal tails. The precise mechanisms through which p53 PTMs operate are difficult to elucidate due to the complexity of p53 signalling and challenges associated with preparing site-specifically modified p53 for in vitro studies. To address these issues, we have developed a protein semi-synthesis strategy to access p53 in defined PTM states.1 Using such ‘designer’ phospho-p53 variants we have probed the mechanism of p53 activation through phosphorylation in vitro. Moreover, we found that the spontaneous rearrangement of an asparagine to an isoaspartate residue in p53 reconfigures binding partner specificity, which suggests that p53 can act as a molecular time bomb. Given the importance of PTMs in p53 signalling, we believe that our chemistry-driven approach will contribute greatly to a mechanistic understanding of how this protein makes cellular life and death decisions.
