Restoration of wild-type conformation to full-length and truncated p53 proteins: Specific effects of ATP and ADP

Mutations in the core domain of the tumor suppressor p53 gene occur in over 50% of human cancers and are not present in normal cells hence p53 protein is a prime target for anti-cancer therapy. In full-length p53 protein, mutations have been shown to destabilise protein structure from wild-type to mutant conformation resulting in differential exposure of conformational epitopes PAb1620, PAb240 and PAb246 in murine p53 protein. In recent studies, putative anti-cancer agents have been designed for rescuing wild-type p53 conformation and function. Using full-length and truncated murine p53 proteins derived from the baculoviral system, we analysed the recovery of PAb246 and PAb1620 epitopes and have identified regions of p53 required for optimal renaturation in vitro to wild-type. The influence of ATP and ADP on the process was also determined. We demonstrate a difference in the dose-dependent effect of ATP and ADP on renaturation of full-length wildtype and monomeric p53 proteins. Putative ATP binding sites were identified at residues 1- 67 and 98-303 in conjunction with a putative ADP binding site at residues 98-303 and negative regulation of ATP/ADP binding by the proline-rich region. Improved efficacy and reduced toxicity of anti-cancer therapy may depend upon compounds engineered to rescue hot-spot core mutations in the context of full-length p53.